- The notorious 'option <unknown> ... larger than buffer' log line,

[thirdparty/dhcp.git] / RELNOTES

	      Internet Systems Consortium DHCP Distribution
		              Version 4.1.0
			     5 December 2008

			      Release Notes

			      NEW FEATURES

ISC DHCP 4.1.x includes several new DHCPv6 features that were not included
in DHCP 4.0.x.  These include:

- Support for the rapid-commit option on the client side

- Prefix Delegation support

- IA_TA address support

- A basic DHCPv6 relay agent

- Basic and partial DHCPv6 leasequery support

There are a number of DHCPv6 limitations and features missing in this
release, which will be addressed in the future:

- Only Solaris, Linux, FreeBSD, NetBSD, and OpenBSD are supported.

- Only a single address is supported per IA.

- DHCPv6 includes human-readable text in status code messages. These
  should be configurable, and probably localized via gettext() or the
  like.

- The "host-identifier" option is limited to a simple token.

- The client and server can only operate DHCPv4 or DHCPv6 at a time,
  not both.  To use both protocols simultaneously, two instances of the
  relevant daemon are required, one with the '-6' command line option.

For information on how to install, configure and run this software, as
well as how to find documentation and report bugs, please consult the
README file.

ISC DHCP uses standard GNU configure for installation. Please review the
output of "./configure --help" to see what options are available.

The system has only been tested on Linux, FreeBSD, and Solaris, and may not
work on other platforms. Please report any problems and suggested fixes to
<dhcp-users@isc.org>.

			Changes since 4.1.0 (bug fixes)

- Validate the argument to the -p option.

- The notorious 'option <unknown> ... larger than buffer' log line,
  which is seen in some malformed DHCP client packets, was modified.
  It now logs the universe name, and does not log the length values
  (which are bogus corruption read from the packet anyway).  It also
  carries a hopefully more useful explanation.

                        Changes since 4.1.0b1

- A missing "else" in dhcrelay.c could have caused an interface not to
  be recognized.

			Changes since 4.1.0a2

- A cosmetic bug in DHCPDECLINE processing was fixed which caused all
  successful DHCPDECLINEs to be logged as "not found" rather than
  "abandoned".

- Added configuration file examples for DHCPv6.

- Some failover debugging #defines have been better defined and some
  high frequency messages moved to a deeper debugging symbol.

- The CLTT parameter in failover is now only updated by client activity,
  and not by failover binding updates (taking on the peer's CLTT).

- Failover BNDUPD messages are now discarded if they conflict with an
  update that has been transmitted, but not acknowledged.

- A bug cleaning up unknown-xxx temporary option definitions was fixed.

- Delayed-ack is now a compile-time option, compiled out by default.
  This feature is simply too experimental for right now, and causes
  some problems to some failover installations.  We will revisit this
  in future releases.

- The !inet_pton() call in res_mkupdrec was adjusted to '<= 0' as
  inet_pton returns either 1, 0, or -1.

- A dhclient-script for MacOS X has been included, which enables
  'dhclient -6' support.

			Changes since 4.1.0a1

- Corrected list of failover state values in dhcpd man page.

- Fixed a bug that caused some request types to be logged incorrectly.

- Clients that sent a parameter request list containing the
  routers option before the subnet mask option were receiving
  only the latter.  Fixed.

- The server wasn't always sending the FQDN option when it should.

- A partner-down failover server no longer emits 'peer holds all free leases'
  if it is able to newly-allocate one of the peer's leases.

- Fixed a coredump when adding a class via OMAPI.

- Check whether files are zero length before trying to parse them.

- Ari Edelkind's PARANOIA patch has been included and may be compiled in
  via two ./configure parameters, --enable-paranoia and
  --enable-early-chroot.

- ./configure was extended to cover many optional build features, such
  as failover, server tracing, debugging, and the execute() command.

- There is now a default 1/4 of a second scheduled delay between delayed
  fsync()'s, it can be configured by the max-ack-delay configuration
  parameter.

- A bug was fixed where the length of a hostname was miscalculated, so that
  hosts were given odd-looking domain names ("foo.bar.ba.example.com").

- Shared network selection should be done from the innermost relay
  valid link-address field, rather than the outermost.

- Prefix pools are attached to shared network scopes.

- Merged IA_XX related structures.

- Add DHCPv6 files in configure.

- A memory leak when using omapi has been fixed.

- DHCPv6 vendor-class options (VSIO) are now only sent when they appear
  on the DHCPv6 ORO.  This resolves a bug where VSIO options were placed
  in IA_NA encapsulated options fields.

- Integrated client with stateless, temporary address and prefix delegation
  support.

- A double-dereference in dhclient transmission of DHCPDECLINEs was
  repaired.

- Fix handling of format code 'Z'.

- Support "-1" argument in DHCPv6.

- Merge DHCPv6-only "dhcrelay6" into general-purpose "dhcrelay" (use
  "-6" option to select DHCPv6 mode).

- Fix handling of -A and -a flags in dhcrelay; it was failing to expand
  packet size as needed to add relay agent options.

- A bug in subnet6 parsing where options contained in subnet6 clauses would
  not be applied to clients addressed within that network was repaired.

- When configuring a "subnet {}" or "subnet6 {}" without an explicit
  shared-network enclosing it, the DHCP software would synthesize a
  shared-network to contain the subnet.  However, all configuration
  parameters within the subnet more intuitively belong "to any client
  on that interface", or rather the synthesized shared-network.  So,
  when a shared-network is synthesized, it is used to contain the
  configuration present inside the subnet {} clause.  This means that
  the configuration will be valid for all clients on that network, not
  just those addressed out of the stated subnet.  If you intended the
  opposite, the workaround is to explicitly configure an empty
  shared-network.

- A bug was fixed where Information-Request processing was not sourcing
  configured option values.

- A warning was added since the DHCPv6 processing software does not yet
  support class statements.

- Compliation warnings on GCC 4.3 relating to bootp source address
  selection were repaired.

- The v6 BSD socket method was updated to use a single UDP BSD socket
  no matter how many interfaces are involved, differentiating the
  interfaces the packets were received on by the interface index supplied
  by the OS.

- The relay agent no longer listens to the All DHCP Servers Multicast
  address.

- A bug was fixed in data_string_sprintfa() where va_start was only called
  once for two invocations of vsprintf() variants.

- ERO (RFC 4994) server support.

- Basic and partial DHCPv6 leasequery support.

- Reliable DHCPv6 release (previous behavior, send release and exit, is
  still available with dhclient -6 -1 -r).

			Changes since 4.0.0 (new features)

- Added DHCPv6 rapid commit support.

- Added explicit parser support for zero-length DHCP options, such as
  rapid-commit, via format code 'Z'.

- It's now possible to update the "ends" field of a lease with OMAPI.
  This is useful if you want not only to release a lease, but also make
  it available for reuse right away.  Hat tip to Christof Chen.

- Fixed definition of the iaaddr hash functions to use the correct 
  functions when referencing and dereferencing memory.

- Some definitions not in phase with the IANA registry were updated.

- Allocated interface IDs are better controlled ('u' bit set to zero,
  reserved IDs avoided).

- Unicast options are taken into account only for RENEWs.

- NoAddrsAvail answers to SOLICITs are always ADVERTISEs even when a SOLICIT
  carries a rapid-commit option.

- Return in place of raise an impossible condition when one tries to release
  an empty active lease.

- Timer granularity is now 1/100s in the DHCPv6 client.

- The dhclient-script was updated to create a host route for the default
  gateway if the supplied subnet mask for an IPv4 address was a /32.  This
  allows the client to work in 'captive' network environments, where the
  operator does not want clients to crosstalk directly.

- MINUS tokens should be parseable again.

- Multiple (up to "delayed-ack x;" maximum) DHCPv4 packets are now queued and
  released in bursts after single fsync() events when the upper limit is
  reached or if the receiving sockets go dry.  The practical upshot is
  that fsync-coupled server performance is now multiplicitively increased.
  The default delayed ack limit is 28.  Thanks entirely to a patch from
  Christof Chen.

			Changes since 4.0.0 (bug fixes)

- DHCP now builds on AIX.

- Exit with warning when DHCPv6-specific statements are used in the
  config file but -6 is not specified.

- Fixed "--version" flag in dhcrelay

- The 'min-secs' configuration parameter's log message has been updated to
  be more helpful.

- The warning logged when an address range doesn't fit in the subnets
  they were declared has been updated to be more helpful and identify the
  typo in configuration that created the spanning addresses.

- A bug in failover pool rebalancing that caused POOLREQ message ping-pongs
  was repaired.

- A flaw in failover pool rebalancing that could cause POOLREQ messages to
  be sent outside of the min-balance/max-balance scheduled intervals has
  been repaired.

- A cosmetic bug during potential-conflict recovery that caused the peer's
  'conflict-done' state message to be logged as 'unknown-state' has been
  repaired.  It is now logged correctly.

- A bug was fixed where the 'giaddr' may be used to find the client's subnet
  rather than its own 'ciaddr'.

- A log message was introduced to clarify the situation where a failover
  'address' parameter (the server's local address) did not resolve to an
  IPv4 address.

- The minimum site code value was set to 224 in 3.1.0 to track RFC3942.  This
  broke a lot of legacy site local configurations.  The new code in place will
  track site local space minimum option codes and logs a warning to encourage
  updates and exploration of site local code migration problems.  Option
  codes less than 128 in site local spaces remain inaccessible.

- A possible relay agent option bug was repaired where random server
  initialization state may have been used to signal the relay agent
  information options sub-option code for the 'END' of the option space.

- Fixes to allow code to compile and run on Solaris 9.

- Fixes to allow code to compile on Mac OS X Leopard (10.5).

- When server is configured with options that it overrides, a warning is
  issued when the configuration file is read, rather than at the time the
  option is overridden. This was important, because the warning was given
  every time the option was overridden, which could create a lot of 
  unnecessary logging.

- Fixed a compilation problems on platforms that define a value for FDDI,
  which conflicts with a dhcp configuration syntax token by the same name.

- When a failover server suspects it has encountered a peer running a
  version 3.0.x failover server, a warning that the failover wire protocol
  is incompatible is printed.

- The failover server no longer issues a floating point error if it encounters
  a previously undefined option code.

- Fix startup error messages to report a missing "subnet6 declaration", rather
  than a missing "subnet declaration", when running as a DHCPv6 server.

- DHCPv6 client timestamp in DUID was based on the year 1970 rather 
  than the year 2000.

- Warn when attempting to use a hardware parameter in DHCPv6.

- DHCPv6 released resources are now marked as released by the client.

- 'Soft' bindings have no more side-effects.

			Changes since 4.0.0b3

- The reverse dns name for PTR updates on IPv6 addresses has been fixed to
  use ip6.arpa. rather than default to in-addr.arpa and require user
  configuration.

- dhc6_lease_destroy() and dhc6_ia_destroy() now set lease and IA pointers
  to NULL after freeing, to prevent subsequent accesses to freed memory.

- The DHCPv6 server would not send the preference option unless the 
  client requested it, via the ORO. This has been fixed, so the DHCPv6
  server will always send the preference value if it is configured.

- When addresses were passed as hints to the server in an IA, they were 
  incorrectly handled, sometimes being treated as an error. Now the 
  server will treat these as hints and ignore them if it cannot supply
  a requested address.

- If the client had multiple addresses, and one expired (was not renewed
  by the server), the client would continue to attempt to renew the same
  old address over and over.  Now, the client will omit any expired
  addresses from future Confirm, Renew, or Rebind messages.

- dhclient -6 will now select renew/rebind timers based upon the longest
  address expiration time rather than the shortest expiration time, in
  order to avoid cascading renewals in the event a server elects not to
  extend one of multiple IAADDR leases.

- The server now limits clients that request multiple addresses to one
  address per IA by default, which can be adjusted through the
  "limit-addrs-per-ia" configuration option.

- The DHCPv6 client now issues fresh transaction IDs on Renew and Rebind
  message exchanges, rather than using the most recent ID.

- The DHCPv6 server now replies to Information-Request messages.

- A bug was fixed in the dhclient-script for BSDs to correctly carry error
  codes through some conditions.

- The parsing of some options in the dhclient lease file, in particular
  the success DHCPv6 status-code, was fixed.

- A bug was fixed that caused the DHCPv6 ORO option to be corrupted with
  seemingly random values.

- A reference overleak in DHCPv6 shared network processing was repaired.

- ./configure now autodetects local database locations rather than trying
  to put dhcpd.leases and dhclient.leases in /usr/local/var/db, which no
  one ever has.

- Regression fix for bug where server advertised a IPv6 address in 
  response to a SOLICIT but would not return the address in response 
  to a REQUEST.

- A bug was fixed where the DHCPv6 server puts the NoAddrsAvail status
  code in the IA_NA was fixed.  The status code now appears in the root
  level.

			Changes since 4.0.0b2

- Clarified error message when lease limit exceeded

- Relative time may now be used as a qualifier for 'allow' and 'deny' access
  control lists.  These directives may be used to assist in re-addressing
  address pools without having to constantly reconfigure the server.  Please
  see 'man dhcpd.conf' for more information on allow/deny 'after time' syntax.
  Thanks to a patch from Christof Chen.

- The server will now include multiple IA_NA's and multiple IAADDRs within
  them, if advertised by the client.  It still only seeks to allocate one
  new address.

			Changes since 4.0.0b1

- Use different paths for PID and lease files when running in DHCPv4
  or DHCPv6 mode, so that servers for both protcols can be run
  simultaneously on a single interface.

- Fixed a buffer overflow error which could have allowed a denial
  of service under unusual server configurations

- Eliminated a spurious error message from the client

- A number of bugs with the internal handling of lease state on the 
  server have been fixed. Some of these could cause server crashes.

- The peer_wants_leases() changes pulled up from 3.1.0 were corrected,
  'never used' leases will no longer consistently shift between servers
  on every pool rebalance run.

- sendmsg()/recvmsg() control buffers are now declared in such a way to
  ensure they are correctly aligned on all (esp. 64-bit) architectures.

- The client leasing subsystem was streamlined and corrected to account
  more closely for changes in client link attachment selection.

			Changes since 4.0.0a3

- The DHCP server no longer requires a "ddns-update-style" statement, 
  and now defaults to "none", which means DNS updates are disabled.

- Log messages when failover peer names mismatch have been improved to
  point out the problem.

- Bug where server advertised a IPv6 address in response to a SOLICIT 
  but would not return the address in response to a REQUEST. Thanks to
  Dennis Kou for finding the bug.

- Fixed an error causing the server to lock up on lease expiration,
  reported independently by Jothilingam Vasu and Dennis Kou.

- Fixed a ./configure bug where compile tests were failing due to
  "-Werror" (unused variable) rather than the actual test failure.  Lead
  to inconsistent and unworkable auto-configurations.

- Compilation with DLPI and -Werror has been repaired.

- Error in decoding IA_NA option if multiple interfaces are present 
  fixed by Marcus Goller.

- DHCPv6 server Confirm message processing has been enhanced - it no
  longer replies only to clients with host {} records, it now replies
  as directed in RFC3315 section 18.2.2 - that is, to all clients
  regardless of the existence of bindings.

- A core dump during expired lease cleanup has been repaired.

- DDNS updates state information are now stored in 'binding scopes' that
  follow the leases through their lifecycles.  This enables DDNS teardowns
  on leases that are assigned and expired inbetween a server restart (the
  state is recovered from dhcpd.leases).  Arbitrary user-specified binding
  scopes ('set var = "value";') are not yet supported.

- Additional compilation problems on HP/UX have been repaired.

			Changes since 4.0.0a2

- Fix for startup where there are no IPv4 addresses on an interface.
  Thanks to Marcus Goller for reporting the bug.

- Fixed file descriptor leak on listen failure. Thanks to Tom Clark.

- Bug in server configuration parser caused server to get stuck on
  startup for certain bad pool declarations. Thanks to Guillaume 
  Knispel for the bug report and fix.

- Code cleaned to remove warnings reported by "gcc -Wall".

- DHCPv6 is now the default. You can disable DHCPv6 support using the
  "--disable-dhcpv6" flag when you run the configure script.

- An internal database inconsistency bug was repaired where the server
  would segfault if a client attempted to renew a lease that had been
  loaded from persistent storage.

- 'request' and 'also request' syntaxes have been added to accommodate
  the DHCPv6 client configuration.  'send dhcp6.oro' is no longer
  necessary.

- Bug fixed where configuration file parsing did not work with 
  zero-length options; this made it impossible to set the 
  rapid-commit option.

- Bogus messages about host records with IPv4 fixed-addresses being of
  non-128-bits in length were removed.

			Changes since 4.0.0a1

- Bug in octal parsing fixed. Thanks to Bernd Fuhrmann for the report
  and fix.

- Autoconf now supplies proper flags for Solaris DHCPv6 builds.

- Fix for parsing error on some IPv6 addresses.

- Invalid CIDR representation for IPv6 subnets or ranges now checked
  for when loading configuration.

- Compilation on HP/UX has been repaired.  The changes should generally
  apply to any architecture that supplies SIOCGLIFCONF but does not
  use 'struct lifconf' structures to pass values.

- Two new operators, ~= and ~~, have been integrated to implement
  boolean matches by regular expression (such as may be used in
  class matching statements).  Thanks to a patch by Alexandr S.
  Agranovsky, which underwent slight modification.

- Fix for icmp packets on 64-bit systems (bug introduced in 4.0).

- A bug was fixed in interface discovery wherein an error identifying
  a server-configured interface with no IPv4 addresses would SEGV.

- Fixed a bug in which write_lease() might report a failure incorrectly

- Added support for DHCPv6 Release messages

- Added -x option to dhclient, which triggers dhclient processes
  to exit gracefully without releasing leases first

- All binaries (client, server, relay) now change directories
  to / before going into daemon mode, so as not to hold $CWD open

- Fixed a bug parsing DHCPv6 client-id's in host-identifier statements

- Fixed a bug with the 'ddns-updates' boolean server configuration
  parameter, which caused the server to fail.

			Changes since 4.0.0-20070413

- Old (expired) leases are now cleaned.

- IPv6 subnets now have support for arbitrary allocation ranges via
  a new 'range6' configuration directive.

- An obviated option code hash lookup to find D6O_CLIENTID was removed.

- Corrected some situations where variables might be used without being
  initialized.

- Silenced several other compiler warnings.

- Include the more standard sys/uio.h rather than rely upon other
  header files to include it (fixes a BSD 4.2 compile failure).

- Duplicate dhclient-script updates for DHCPv6 to all provided scripts.

- DHCPv4 I/O methods that failed to sense hardware address were corrected.

- DHCPv4 is now the default (as documented) rather than DHCPv6.  The default
  was set to DHCPv6 to facilitate ease early development, and forgotten.

- Corrected a segmentation violation in DHCPv4 socket processing.

- dhclient will now fork() into the background once it binds to an
  IPv6 address, or immediately if the -n flag is supplied.

- -q is now the default behaviour on dhclient, with -d or -v enabling
  non-quiet (stderr logging) mode.

- Fix documentation of the domain-search atom (quoted, with commas).

- Document DHCPv6 options presently in the default table.

- Replaced ./configure shellscripting with GNU Autoconf.

		     Changes since 3.1.0 (NEW FEATURES)

- DHCPv6 Client and Server protocol support.  Use '-6' to run the daemons
  as v6-only.  Use '-4' to run the daemons as v4-only (default.  There is
  no support currently for both.

- Server support for multiple IA_NA options, containing at most one
  IAADDR option.

- Client support for one IA_NA option, containing any number of IAADDR
  options.

- Server support for the DHCPv6 Information-request message.

- Inappropriate unicast DHCPv6 messages sent to the server are now
  discarded, and this has rearchitected the IO system slightly.

- The DHCPv6 server DUID defaults to type 1, is persistently stored in
  the leases database, and can be over-ridden (either completely, or by
  specifying type 1 or type 2).

- The server only uses Rapid-Commit if it has been configured with the
  Rapid-Commit option and the client requests it.

- DDNS support. We now update AAAA records in the same place we would
  update A records, if we have an IPv6 address. We also generate IP6.ARPA
  style names for PTR records if we're dealing with an IPv6 address.  Both
  A and AAAA updates are done using the same 'fqdn.' virtual option space
  (although the DHCPv4 FQDN and DHCPv6 FQDN options are formatted
  differently, they both use the same code here).

- The Linux dhclient-script attempts to set and remove assigned addresses,
  and to configure /etc/resolv.conf from nameserver and domain name
  configurations.  It can be extended to configure other parameters.

- Initial DHCPv6 lease support.

- The IO system now tracks all local IP addresses, so that the DHCP
  applications (particularly the dhcrelay) can discern between what frames
  were transmitted to it, and what frames are being carried through it which
  it should not intercept.

			Changes since 3.1.0 (Maintenance)

- A bug was repaired where MAC Address Affinity for virgin leases always
  mapped to the primary.  Virgin leases now have an interleaved preference
  between primary and secondary.

- A bug was repaired where MAC Address Affinity for clients with no client
  identifier was sometimes mishashed to the peer.  Load balancing during
  runtime and pool rebalancing were opposing.

- An assertion in lease counting relating to reserved leases was repaired.

- The subnet-mask option inclusion now conforms with RFC2132 section 3.3;
  it will only appear prior to the routers option if it is present on the
  Parameter-Request-List.  The subnet-mask option will also only be
  included by default (if it is not on the PRL) in response to DISCOVER
  or REQUEST messages.

- The FQDN option is only supplied if the client supplied an FQDN option or
  if the FQDN option was explicitly requested on the PRL.

- Dynamic BOOTP leases are now load balanced in failover.

			Changes since 3.1.0rc1

- The parse warning that 'deny dyanmic bootp;' must be configured for
  failover protected subnets was removed.

			Changes since 3.1.0b2

- Failover rebalance events no longer play ping pong with round errors
  (moving leases between free and back to backup where there are an
  odd number of leases).

- The 'pool' log line has been split into two messages, one before the
  rebalance run, and one after.

- Any queued BNDACKs are transmitted before transmitting new BNDUPDs.
  This enforces the correct sequence of events for the remote server
  processing these messages.

			Changes since 3.1.0b1

- Fixed a bug that caused OMAPI clients to freeze when opening lease
  objects.

- A new server config option "fqdn-reply" specifies whether the server
  should send out option 81 (FQDN).  Defaults to "on".  If set to "off",
  the FQDN option is not sent, even if the client requested it.  This is
  needed because some clients misbehave otherwise.  Thanks to Christof Chen
  at Allianz.

- Allow trace output files (-tf option) to be overwritten, rather than
  crashing dhcpd if the file already exists

- A bug was fixed that caused dhcpd to segfault if a pool was declared
  outside the scope of a subnet in dhcpd.conf.

- Some uninitialized values were repaired in dhcpleasequery.c that
  caused the server to abort.

- A new server config option, 'do-reverse-updates', has been added
  which causes the server to abstain from performing updates on PTR
  records.  Thanks to a patch from Christof Chen at Allianz.

- A bug was repaired in subencapsulation support, where spaces separated
  by empty spaces would not get included.

- A bug in dhclient was repaired which caused it to send parameter request
  lists of 55 bytes in length no matter how long the declared PRL was.

- 'dhcp.c(3953): non-null pointer' has been repaired.  This fixes a flaw
  wherein the DHCPv4 server may ignore a configured server-identifier.

- A flaw in failover startup sequences was repaired that sometimes left
  the primary DHCP server's pool rebalance schedules unscheduled.

- Corrected a flaw that broke encapsulated spaces included due to presence
  on the parameter request list.

			Changes since 3.1.0a3

- Some spelling fixes.

			Changes since 3.1.0a2

- A bug was fixed where attempting to permit leasequeries results in a
  fatal internal error, "Unable to find server option 49".

- A bug was fixed in dhclient rendering the textual output form of the
  domain-search option syntax.

			Changes since 3.1.0a1

- A bug in the FQDN universe that added FQDN codes to the NWIP universe's
  hash table was repaired.

- The servers now try harder to transmit pending binding updates when
  entering normal state.

- UPDREQ/UPDREQALL handling was optimized - it no longer dequeues and
  requeues all pending updates.  This should reduce the number of spurious
  'xid mismatch' log messages.

- An option definition referencing leak was fixed, which resulted in early
  termination of dhclient upon the renewal event.

- Some default hash table sizes were tweaked, some upwards, some downwards.
  3.1.0a1's tables resulted in a reduction in default server memory use.
  The new selected values provide more of a zero sum (increasing the size
  of tables likely to be populated, decreasing the size of tables unlikely).

- Lease structures appear in three separate hashes: by IP address, by UID,
  and by hardware address.  One type of table was used for all three, and
  improvements to IP address hashing were applied to all three (so UID and
  hardware addresses were treated like 4-byte integers).  There are now two
  types of tables, and the uid/hw hashes use functions more appropriate
  to their needs.

- The max-lease-misbalance percentage no longer causes scheduled rebalance
  runs to be skipped: it still governs the schedule, but every scheduled
  run will attempt balance.

- A segfault bug in recursive encapsulation support has been corrected.

			Changes since 3.0 (New Features)

- A workaround for certain STSN servers that send a mangled domain-name
  option was introduced for dhclient.  The client will now accept corrupted
  server responses, if they contain a valid DHCP_MESSAGE_TYPE (OFFER, ACK,
  or NAK).  The server will continue to not accept corrupt client packets.

- Support for 'reserved' (pseudo-static) and BOOTP leases via failover
  was introduced.

- Support for adding, removing, and managing class and subclass statements
  via OMAPI.

- The failover implementation was updated to comply with revision 12 of
  the protocol draft.

- 'make install' now creates the initial zero-length dhcpd.leases file if
  one does not already exist on the system.

- RFC3942 compliance, site-local option spaces start at 224 now, not 128.

- The Load Balance Algorithm was misimplemented.  The current implementation
  matches RFC 3074.

- lcase() and ucase() configuration expressions have been added which adjust
  their arguments from upper to lower and lower to upper cases respectively.
  Thanks to a patch from Albert Herranz.

- The dhclient 'reject ...;' statement, which rejects leases given by named
  server-identifiers, now permits address ranges to be specified in CIDR
  notation.  Thanks to a patch from David Boyce.

- The subnet-mask option is now supplied by default, but at lowest
  priority.  This helps a small minority of clients that provide parameter
  request lists, but do not list the subnet-mask option because they were
  designed to interoperate with a server that behaves in this manner.

- The FQDN option is similarly supplied even if it does not appear on the
  parameter request list, but not to the exclusion of options that do
  appear at the parameter request list.  Up until now it had ultimate
  priority over the client's parameter request list.

- Varying option space code and length bit widths (8/16/32) are now
  supported.  This is a milestone in achieving RFC 3925 "VIVSO" and
  DHCPv6 support.

- A new common (server or client) option, 'db-time-format local;', has
  been added which prints the local time in /var/db/dhcpd.leases rather
  than UTC.  Thanks to a patch from Ken Lalonde.

- Some patches to improve DHCP Server startup speed from Andrew Matheson
  have been incorporated.

- Failover pairs now implement 'MAC Affinity' on leases moving from the
  active to free states.  Leases that belonged to the failover secondary
  are moved to BACKUP state rather than FREE upon exiting EXPIRED state.
  If lease rebalancing must move leases, it tries first to move leases
  that belong to the peer in need.

- The server no longer sends POOLREQ messages unless the pool is severely
  misbalanced in the peer's favor (see 'man dhcpd.conf' for more details).

- Pool rebalance events no longer happen upon successfully allocating a
  lease.  Instead, they happen on a schedule.  See 'man dhcpd.conf' for the
  min-balance and max-balance statements for more information.

- The DHCP Relay Agent Information Option / Link Selection Sub-Option
  is now supported.  (See RFC3527 for details).

- A new DDNS related server option, update-conflict-detection, has been
  added.  If this option is enabled, dhcpd will perform normal DHCID
  conflict resolution (the default).  If this option is disabled, it will
  instead trust the assigned name implicitly (removing any other bindings
  on that name).  This option has not been made available in dhclient.

- In those cases where the DHCP software manufactures an IP header (to
  transmit via bpf, lpf, etc), the IP TTL the software selects has been
  increased from 16 to 128.  This is intended to match Microsoft Windows
  DHCP Client behaviour, to increase compatibility.

- 'ignore client-updates;' now has behaviour that is different from
  'deny client-updates;'.  The client's request is not truly ignored,
  rather it is encouraged.  Should this value be configured, the server
  updates DNS as though client-updates were set to 'deny'.  That is, it
  enters into DNS whatever it is configured to do already, provided it is
  configured to.  Then it sends a response to the client that lets the
  client believe it is performing client updates (which it will), probably
  for a different name.  In essence, this lets the client do as it will,
  ignoring this aspect of their request.

- Support for compressed 'domain name list' style DHCP option contents, and
  in particular the domain search option (#119) was added.

- The DHCP LEASEQUERY protocol as defined in RFC4388 is now implemented.
  LEASEQUERY lets you query the DHCP server for information about a lease,
  using either an IP address, MAC address, or client identifier.  Thanks
  to a patch from Justin Haddad.

- DHCPD is now RFC2131 section 4.1 compliant (broadcast to all-ones ip and
  ethernet mac address) on the SCO platform specifically without any strange
  ifconfig hacks.  Many thanks go to the Kroger Co. for donating the
  hardware and funding the development.

- A new common configuration executable statement, execute(), has been
  added.  This permits dhcpd or dhclient to execute a named external
  program with command line arguments specified from other configuration
  language.  Thanks to a patch written by Mattias Ronnblom, gotten to us
  via Robin Breathe.

- A new dhcp server option 'adaptive-lease-time-threshold' has been added
  which causes the server to substantially reduce lease-times if there are
  few (configured percentage) remaining leases.  Thanks to a patch submitted
  from Christof Chen.

- Encapsulated option spaces within encapsulated option spaces is now
  formally supported.

			Changes since 3.0.6rc1

- supersede_lease() now requeues leases in their respective hardware
  address hash bucket.  This mirrors client identifier behaviour.

			Changes since 3.0.5

- Assorted fixes for broken network devices:  Packet length is now
  determined from the IP header length field to finally calculate the
  UDP payload length, because some NIC drivers return more data than
  they actually received.

- UDP packets are now stored in aligned data structures.

- A logic error in omapi interface code was repaired that might result in
  incorrectly indicating 'up' state when any flags were set, rather than
  specifically the INTERFACE_REQUESTED flag.  Thanks to a patch from
  Jochen Voss which got to us via Andrew Pollock at Debian.

- A reference leak on binding scopes set by ddns updates was repaired.

- A memory leak in the minires_nsendsigned() function call was repaired.
  Effectively, this leaked ~176 bytes per DDNS update.

- In the case where an "L2" DHCP Relay Agent (one that does not set giaddr)
  was directly attached to the same broadcast domain as the DHCP server,
  the RFC3046 relay agent information option was not being returned to the
  relay in the server's replies.  This was fixed; the dhcp server no longer
  requires the giaddr to reply with relay agent information.  Note that
  this also improves compatibility with L2 devices that "intercept" DHCP
  packets and expect relay agent information even in unicast (renewal)
  replies.  Thanks to a patch from Pekka Silvonen.

- A bug was fixed where the BOOTP header 'sname' field had a value, the
  copy written to persistent storage was actually the contents of the
  'file' field.

- A bug was fixed where the nwip virtual option space was referencing
  the fqdn option's virtual option space's option cache.

- Timestamp parsing errors that indicated missing "minutes" fields rather
  than the actually missing "seconds" fields have been repaired thanks to
  a patch from Kevin Steves.

- A grammar error in the dhclient.8 manpage was repaired thanks to a patch
  from Chris Wagner.

- Several spelling typos were repaired, and some cross-references to other
  relevant documents were included in the manpages, thanks to a patch
  by Andrew Pollock which got to us via Tomas Pospisek.

- Some bugs were fixed in the 'emergency relay agent options hologram'
  which is used to retain relay agent option contents from when the
  client was in INIT or REBIND states.  This should solve problems where
  relay agent options were not echoed from the server, even when giaddr
  was set.

- dhclient now closes its descriptor to dhclient.leases prior to executing
  dhclient-script.  Thanks to a patch from Tomas Pospisek.

- The server's "by client-id" and "by hardware address" hash table lists
  are now sorted according to the preference to re-allocate that lease to
  returning clients.  This should eliminate pool starvation problems
  arising when "INIT" clients were given new leases rather than presently
  active ones.

			Changes since 3.0.5rc1

- A bug was repaired in fixes to the dhclient, which sought to run the
  dhclient-script with the 'EXPIRE' state should it receive a NAK in
  response to a REQUEST.  The client now iterates the PREINIT state
  after the EXPIRE state, so that interfaces that might be configured
  'down' can be brought back 'up' and initialized.

- DHCPINFORM handling for clients that properly set ciaddr and come to the
  server via a relay aget has been repaired.

			Changes since 3.0.4

- A warning that host statements declared within subnet or shared-network
  scopes are actually global has been added.

- The default minimum lease time (if min-lease-time was not specified)
  was raised from 0 to 300.  0 is not thought to be sensible, and is
  known to be damaging.

- Added additional fatal error sanity checks surrounding lease binding
  state count calculations (free/active counts used for failover pool
  balancing).

- Some time value size fixes in 3.0.4 brought on from FreeBSD /usr/ports were
  misapplied to server values rather than client values.  The server no longer
  advertises 8-byte lease-time options when on 64-bit platforms.

- A bug where leases not in ACTIVE state would get billed to billed classes
  (classes with lease limitations) was fixed.  Non-active leases OFFERed
  to clients are no longer billed (but billing is checked before offering).

- The dhcpd.conf.5 manpage was updated in regard to the ddns-domainname
  configuration option - the default configuration and results should be
  more clear now.

- If the dhclient were to receive a DHCPNAK while it was in the RENEW
  state (and consequently, had an active, 'bound' address and related
  configuration options), it would fail to 'tear down' this information
  before proceeding into INIT state.  dhclient now iterates the dhclient-
  script with the 'EXPIRE' action to cause these teardowns prior to entering
  INIT state.  Thanks to a patch from Chris Zimmerman.

- The omapi.1 manpage had some formatting errors repaired thanks to a patch
  from Yoshihiko Sarumaru.

- A few lines of code that were failover-specific were moved within
  #if defined() clauses so that compilation without failover could be
  made possible.

- The log message emitted when the 'leased-address' value was not available
  in dhcpd.conf "executable statements" has been updated to be more helpful.
  Manpage information for this value has also been updated.

- Abandoned or dissociated (err condition) leases now remove any related
  dynamic dns bindings.  Thanks to a patch from Patrick Schoo.

- Attempting to write a new lease file to replace a corrupt (due to
  encountering non-retryable errors during writing) lease file should
  no longer result in an infinite recursion.

- Host declaration hardware addresses and client identifiers may only be
  configured once.  dhcpd will now fail to load config files that specify
  multiple identifiers (previous versions would silently over-ride the
  value with the later configured value).

- Several option codes that have been allocated since our last release
  have been named and documented.

- Option names of the form "unknown-123" have been removed from the in-
  memory hash tables.  In order to support options of these names that
  may appear in dhclient.leases or similar in previous versions, the
  parser will now find the new option code definition, or mock up a
  generic option code definition.  This should result in a smooth
  transition from one name to the other, as the new name is used to
  write new output.

			Changes since 3.0.4rc1

- The dhcp-options.5 manpage was updated to correct indentation errors
  thanks to a patch from Jean Delvare.

			Changes since 3.0.4b3

- Some manual pages were clarified pursuant to discussion on the dhcp-server
  mailing list.

			Changes since 3.0.4b2

- Null-termination sensing for certain clients that unfortunately require
  it in DHCPINFORM processing was repaired.

- The host-name option and a few others were moved from "X" format to "t"
  format to be compatible with new NULL handling functions.

- DHCPINFORM processing is a little more careful about return addressing
  its responses, or if responding via a relay.  The INFORM related
  messages also log the 'effective client ip address' rather than the
  client's supplied ciaddr (since some clients produce null ciaddrs).

- The server was inappropriately sending leases to the RESET state in the
  event that multiple active leases were found to match a singly-identified
  client.  This was changed to RELEASED (by accepting a different, ACTIVE
  binding, the client is implicitly releasing its lease).  This repairs a
  bug wherein secondary servers in failover pairs detecting this condition
  move leases to RESET, and primaries refuse to accept that state
  transition (properly).

- The memset-after-dmalloc() changes made in 3.0.4b1 have been backed out.

			Changes since 3.0.4b1

- Command line parsing in omshell was repaired - it no longer closes
  STDIN after reading one line.

- The resolver library no longer closes the /etc/resolv.conf file
  descriptor it opened twice.

- Changes to trailing NULL removal in 't' option-atoms has been rethought,
  it now includes 'd' (domain name) types, and tries hard not to rewind an
  option beyond the start of the text field it is un-terminating.

			Changes since 3.0.3

- A DDNS update handling function was misusing the DNS error codes, rather
  than the internal generic result enumeration.  The result is a confusing
  syslog line, logging the wrong condition.

- The DHCP Server was not checking pool balance in the case where it brought
  a non-ACTIVE lease out of storage for a client that was returning to use
  a lease it once had long ago, and had since expired.

- Failover peers no longer bother to look for free leases to allocate when
  they already found the client's ACTIVE lease.  DISCOVERs are load balanced
  whether freely-allocated or not, unless the server doubts the peer has
  leases to allocate.

- Fixed a bug in dhcrelay agent addition code that suppressed trailing
  PAD options - it was suppressing only one trailing PAD option, rather
  than the entire block of them.

! Fixed some unlikely overlapping-region memcpy() bugs in dhcrelay agent
  option addition and stripping code.  Added a few sanity checks.  Although
  highly improbable, due to requiring the reception of a DHCP datagram well
  in excess of all known to be used physical MTU limitations, it is possible
  this may have been used in a stack overflow security vulnerability.  Thanks
  to a patch from infamous42md.

! Added some sanity checks to OMAPI connection/authentication code.
  Although highly improbable, due to having to deliver in excess of 2^32
  bytes of data via the OMAPI channel, not to mention requiring dhcpd to
  be able to malloc() a memory region 2^32 bytes in size, it was possible
  this might have resulted in a heap overflow security vulnerability.
  Thanks to a patch from infamous42md.

- dmalloc() memset()'s the non-debug (data) portion of the allocated
  memory to zero.  Code that memset()'s the result returned by dmalloc() to
  zero is redundant.  These redundancies were removed.

- Some type declaration corrections to u_int16_t were made in common/tr.c
  (Token Ring support) thanks to a patch from Jason Vas Dias at RedHat.

- A failover bug that was allowing leases that EXPIRED or were RELEASED
  where tsfp and tstp are identical timestamps to languish in these
  transitional states has been repaired.  As a side effect, lease
  databases should be kept more consistent overall, not just for these
  transitional states.

- If the lease db is deleted out from under the daemon, and it moves to rewrite
  the db, it will go ahead with the operation and move the new db into place
  once it detects the old db does not exist.

- dhclient now ignores IRDA, SIT, and IEEE1394 network interfaces, as it
  is either nonsensical or (in the case of IEEE1394) is not known to support
  these interfaces.  Thanks to Marius Gedminas and Andrew Pollock of Debian.

- Some previously undocumented reasons for dhclient-script invoking has
  been documented in the dhclient-script.8 manpage.

- Failover potential expiry calculations (TSTP) have been corrected.  Results
  should be substantially more consistent, and proper given the constraints.

- Adjusted lease state validation checks in potential-conflict, to
  account for possible clock skew similarly to normal state, and several
  previously illegal transitions were made legal (ex: active->released).

- An impossible sanity check was removed from omapi/buffer.c, thanks to a
  patch from 'infamous42md'.

- An OMAPI host/network byte order problem in lease time values has been
  repaired.

- Several minor bugs, largely relating to treating 8-byte time values as
  4-byte entities, have been repaired after careful review of the FreeBSD
  ports collection's patch set.  Thanks to the nameless entities who have
  contributed to the FreeBSD ports.

- When writing a trace file, the file is now created with permissions 0600,
  to help administrators avoid accidentally publicising sensitive config
  data.

- The calculation of the maximum size of DHCP packets no longer includes
  Ethernet framing overhead.  The result is that the 'Maximum Message
  Size' option advertised by clients, or the default value 576, is no
  longer reduced by 14 bytes, and instead directly reflects the IP level
  MTU (and the default, minimum allowed IP MTU of 576).

- The special status of RELEASED/EXPIRED/RESET leases when a server
  is operating in partner-down was fixed.  It no longer requires a
  lease be twice the MCLT beyond STOS to 'reallocate', and the expiry
  event to turn these into FREE leases without peer acknowledgement
  (after STOS+MCLT) has been repaired.

- Compilation on older Solaris systems (lacking /usr/include/sys/int_types.h)
  has been repaired.

- "append"ing a string onto the end of a "t" type option (such as the
  domain-name field) that had been improperly NULL-terminated by the
  DHCP server will no longer result in a truncated string containing
  only the option from the server, and not the expected appended value.
  Thanks to a patch from Jason Vas Dias at RedHat.

- File handlers on configuration state (config files and lease dbs) should
  be treated consistently, regardless of whether TRACING is defined or not.

- The Linux build environment has had some minor improvements - better
  sensing of 64-bit pointer sizes (only used for establishing an icmp_id),
  and corrections to #if operators regarding LINUX_MAJOR should it ever
  move to 3.[01].x.

- The server now tries harder to survive the condition where it is unable
  to open a new lease file to rewrite the lease state database.

			Changes since 3.0.3b3

- dhclient.conf documentation for interface {} was updated to reflect recent
  discussion on the dhcp-hackers mailing list.

- In response to reports that the software does not compile on GCC 4.0.0,
  -Werror was removed from Makefile.conf for all platforms that used it.
  We will address the true problem in a future release; this is a temporary
  workaround.

			Changes since 3.0.3b2

- An error in code changes introduced in 3.0.3b2 was corrected, which caused
  static BOOTP clients to receive random addresses.

			Changes since 3.0.3b1

- A bug was fixed in BOOTPREQUEST handling code wherein stale references to
  host records would be left behind on leases that were not allocated to the
  client currently booting (eg in the case where the host was denied booting).

- The dhcpd.conf.5 manpage was updated to be more clear in regards to
  multiple host declarations (thanks to Vincent McIntyre).  'Interim' style
  dynamic updates were also retouched.

			Changes since 3.0.2

- A bug was fixed where a server might load balance a DHCP REQUEST to its
  peer after already choosing not to load balance the preceding DISCOVER.
  The peer cannot allocate the originating server's lease.

- In the case where a secondary server lost its stable storage while the
  primary was still in communications-interrupted, and came back online,
  the lease databases would not be fully transferred to the secondary.
  This was due to the secondary errantly sending an extra UPDREQ message
  when the primary made its state transition to PARTNER-DOWN known.

- The package will now compile cleanly in gcc 3.3 and 3.4.  As a side effect,
  lease structures will be 9 bytes smaller on all platforms.  Thanks to
  Jason Vas Dias at Redhat.

- Interface discovery code in DISCOVER_UNCONFIGURED mode is now
  properly restricted to only detecting broadcast interfaces.  Thanks
  to a patch from Jason Vas Dias at RedHat.

- decode_udp_ip_header was changed so that the IP address was copied out
  to a variable, rather than referenced by a pointer.  This enforces 4-byte
  alignment of the 32-bit IP address value.  Thanks to a patch from Dr.
  Peter Poeml.

- An incorrect log message was corrected thanks to a patch from
  Dr. Peter Poeml.

- A bug in DDNS was repaired, where if the server's first DDNS action was
  a DDNS removal rather than a DDNS update, the resolver library's
  retransmit timer and retry timer was set to the default, implying a
  15 second timeout interval.  Which is a little excessive in a synchronous,
  single-threaded system.  In all cases, ISC DHCP should now hold fast to
  a 1-second timeout, trying only once.

- The siaddr field was being improperly set to the server-identifier when
  responding to DHCP messages.  RFC2131 clarified the siaddr field as
  meaning the 'next server in the bootstrap process', eg a tftp server.
  The siaddr field is now left zeroed unless next-server is configured.

- mockup_lease() could have returned in an error condition (or in the
  condition where no fixed-address was found matching the shared
  network) with stale references to a host record.  This is probably not
  a memory leak since host records generally never die anyway.

- A bug was repaired where failover servers would let stale client identifiers
  persist on leases that were reallocated to new clients not sending an id.

- Binding scopes ("set var = value;") are now removed from leases allocated
  by failover peers if the lease had expired.  This should help reduce the
  number of stale binding scopes on leases.

- A small memory leak was closed involving client identifiers larger than
  7 bytes, and failover.

- Configuring a subnet in dhcpd.conf with a subnet mask of 32 bits might
  cause an internal function to overflow heap.  Thanks to Jason Vas Dias
  at Redhat.

- Some inconsistencies in treating numbers that the lexer parsed as 'NUMBER'
  or 'NUMBER_OR_NAME' was repaired.  Hexadecimal parsing is affected, and
  should work better.

- In several cases, parse warnings were being issued before the lexical
  token had been advanced to the token whose value was causing an error...
  causing parse warnings to claim the problem is on the wrong token.

- Host declarations matching on client identifier for dynamic leases will
  no longer match fixed-address host declarations (this is now identical
  to behaviour for host records matching on hardware address).

			Changes since 3.0.2rc3

- A previously undocumented configuration directive, 'local-address',
  was documented in the dhcpd.conf manpage.

			Changes since 3.0.2rc2

- Two variables introduced in 3.0.2b1 were used without being initialized
  in the case where neither the FILE nor SNAME fields were available for
  overloading.  This was repaired.

- A heretofore believed to be impossible corner case of the option
  overloading implementation turned out to be possible ("Unable to sort
  overloaded options after 10 tries.").  The implementation was reworked
  to consider the case of an option so large it would require more than
  three chunks to fit.

- Many other instances of variables being used without being initialized
  were repaired.

- An uninitialized variable in omapi_io_destroy() led to the discovery
  that this function may result in orphaned pointers (and hence, a memory
  leak).

			Changes since 3.0.2rc1

- allocate_lease() was rewritten to repair a bug in which the server would
  try to allocate an ABANDONED lease when FREE leases were available.

			Changes since 3.0.2b1

- Some dhcp-eval.5 manpage formatting was repaired.

			Changes since 3.0.1

- A bug was fixed in the server's 'option overloading' implementation,
  where options loaded into the 'file' and 'sname' packet fields were
  not aligned precisely as rfc2131 dictates.

- The FreeBSD client script was changed to support the case where a domain
  name was not provided by the server.

- A memory leak in 'omshell' per each command line parsed was
  repaired, thanks to a patch from Jarkko Torppa.

- Log functions writing to stderr were adjusted to use the STDERR_FILENO
  system definition rather than '2'.  This is a no-op for 90% of platforms.

- One call to trace_write_packet_iov() counted the number of io vectors
  incorrectly, causing inconsistent tracefiles.  This was fixed.

- Some expression parse failure memory leaks were closed.

- A host byte order problem in tracefiles was repaired.

- Pools configured in DHCPD for failover possessing permission lists that
  previously were assumed to not include dyanmic bootp clients are now
  a little more pessimistic.  The result is, dhcpd will nag you about just
  about most pools that possess a 'allow' statement with no 'deny' that
  would definitely match a dynamic bootp client.

- The 'ddns-update-style' configuration warning bit now insists that
  the configuration be globally scoped.

- Two memory leaks in dhclient were closed thanks to a patch from Felix
  Farkas.

- Some minor but excellently pedantic documentation errors were fixed
  thanks to a patch from Thomas Klausner.

- Bugs in operator precedence in executable statements have been repaired
  once again.  More legal syntaxes should be parsed legally.

- Failing to initialize a tracefile for any reason if a tracefile was
  specified is now a fatal error.  Thanks to a patch from Albert Herranz.

- Corrected a bug in which the number of leases transferred as calculated
  by the failover primary and sent to peers in POOLRESP responses may be
  incorrect.  This value is not believed to be used by other failover
  implementations, excepting perhaps as logged information.

- Corrected a bug in which 'dhcp_failover_send_poolresp()' was in fact
  sending POOLREQ messages instead of POOLRESP mesasges.  This message
  was essentially ignored since failover secondaries effectively do not
  respond to POOLREQ messages.

- Type definitions for various bitwidths of integers in the sunos5-5
  build of ISC DHCP have been fixed.  It should compile and run more
  easily when built in 64-bit for this platform.

- "allow known-clients;" is now a legal syntax, to avoid confusion.

- If one dhcp server chooses to 'load balance' a request to its failover
  peer, it first checks to see if it believes said peer has a free
  lease to allocate before ignoring the DISCOVER.

- log() was logging a work buffer, rather than the value returned by
  executing the statements configured by the user.  In some cases,
  the work buffer and the intended results were the same.  In some other
  cases, they were not.  This was fixed thanks to a patch from Gunnar
  Fjone and directconnect.no.

- Compiler warnings for some string type conversions was fixed, thanks
  to Andreas Gustafsson.

- The netbsd build environments were simplified to one, in which
  -Wconversion is not used, thanks to Andreas Gustafsson.

- How randomness in the backoff-cutoff dhclient configuration variable
  is implemented was better documented in the manpage, and the behaviour
  of dhclient in REQUEST timeout handling was changed to match that of
  DISCOVER timeout handling.

- Omapi was hardened against clients that pass in null values, thanks
  to a patch from Mark Jason Dominus.

- A bug was fixed in dhclient that kept it from doing client-side
  ddns updates.  Thanks to a patch from Andreas Gustafsson, which
  underwent some modification after review by Jason Vas Dias.

- Failover implementations disconnected due to the network between
  them (rather than one of the two shutting down) will now try to
  re-establish the failover connection every 5 seconds, rather than
  to simply try once and give up until one of them is restarted.
  Thanks to a patch from Ulf Ekberg from Infoblox, and field testing
  by Greger V. Teigre which led to an enhancement to it.

- A problem that kept DHCP Failover secondaries from tearing down
  ddns records was repaired.  Thanks to a patch from Ulf Ekberg from
  Infoblox.

- 64bit pointer sizes are detected properly on FreeBSD now.

- A bug was repaired where the DHCP server would leave stale references
  to host records on leases it once thought about offering to certain
  clients.  The result would be to apply host and 'known' scopes to the
  wrong clients (possibly denying booting).  NOTE:  The 'mis-host' patch
  that was being circulated as a workaround is not the way this bug was
  fixed.  If you were a victim of this bug in 3.0.1, you are cautioned
  to proceed carefully and see if it fixes your problem.

- A bug was repaired in the server's DHCPINFORM handling, where it
  tried to divine the client's address from the source packet and
  would get it wrong.  Thanks to Anshuman Singh Rawat.

- A log message was introduced to help illuminate the case where the
  server was unable to find a lease to assign to any BOOTP client.
  Thanks to Daniel Baker.

- A minor dhcpd.conf.5 manpage error was fixed.

			Changes since 3.0.1rc14

- The global variable 'cur_time' was centralized and is now uniformly of a
  type #defined in system-dependent headers.  It had previously been defined
  in one of many places as a 32-bit value, and this causes mayhem on 64-bit
  big endian systems.  It probably wasn't too healthy on little endian
  systems either.

- A printf format string error introduced in rc14 was repaired.

- AIX system-dependent header file was altered to only define NO_SNPRINTF
  if the condition used to #ifdef in vsnprintf in AIX' header files
  is false.

- The Alpha/OSF system-dependent header file was altered to define
  NO_SNPRINTF on OS revisions older than 4.0G.

- omapip/test.c had string.h added to its includes.

			Changes since 3.0.1rc13

! CAN-2004-0460 - CERT VU#317350: Five stack overflow exploits were closed
  in logging messages with excessively long hostnames provided by the
  clients.  It is highly probable that these could have been used by
  attackers to gain arbitrary root access on systems using ISC DHCP 3.0.1
  release candidates 12 or 13.  Special thanks to Gregory Duchemin for
  both finding and solving the problem.

! CAN-2004-0461 - CERT VU#654390: Once the above was closed, an opening
  in log_*() functions was evidenced, on some specific platforms where
  vsnprintf() was not believed to be available and calls were wrapped to
  sprintf() instead.  Again, credit goes to Gregory Duchemin for finding
  the problem.  Calls to snprintf() are now linked to a distribution-local
  snprintf implementation, only in those cases where the architecture is
  not known to provide one (see includes/cf/[arch].h).  If you experience
  linking problems with snprintf/vsnprintf or 'isc_print_' functions, this
  is where to look.  This vulnerability did not exist in any previously
  published version of ISC DHCP.

- Compilation on hpux 11.11 was repaired.

- 'The cross-compile bug fix' was backed out.

			Changes since 3.0.1rc12

- Fixed a bug in omapi lease lookup function, to form the hardware
  address for the hash lookup correctly, thanks to a patch from
  Richard Hirst.

- Fixed a bug where dhcrelay was sending relayed responses back to the
  broadcast address, but with the source's unicast mac address.  Should
  now conform to rfc2131 section 4.1.

- Cross-compile bug fix; use $(AR) instead of ar.  Thanks to Morten Brorup.

- Fixed a crash bug in dhclient where dhcpd servers that do not provide
  renewal times results in an FPE.  As a side effect, dhclient can now
  properly handle 0xFFFFFFFF (-1) expiry times supplied by servers.  Thanks
  to a patch from Burt Silverman.

- The 'ping timeout' debugs from rc12 were removed to -DDEBUG only,
  and reformatted to correct a compilation error on Solaris platforms.

- A patch was applied which fixes a case where leases read from the
  leases database do not properly over-ride previously read leases.

- dhcpctl.3 manpage was tweaked.

			Changes since 3.0.1rc11

- A patch from Steve Campbell was applied with minor modifications to
  permit reverse dns PTR record updates with values containing spaces.

- A patch from Florian Lohoff was applied with some modifications to
  dhcrelay.  It now discards packets whose hop count exceeds 10 by default,
  and a command-line option (-c) can be used to set this threshold.

- A failover bug relating to identifying peers by name length instead of
  by name was fixed.

- Declaring failover configs within shared-network statements should no
  longer result in error.

- The -nw command line option to dhclient now works.

- Thanks to a patch from Michael Richardson:
	- Some problems with long option processing have been fixed.
	- Some fixes to minires so that updates of KEY records will work.

- contrib/ms2isc was updated by Shu-Min Chang of the Intel Corporation.
  see contrib/ms2isc/readme.txt for revision notes.

- Dhclient no longer uses shell commands to kill another instance of
  itself, it sends the signal directly.  Thanks to a patch from Martin
  Blapp.

- The FreeBSD dhclient-script was changed so that a failure to write to
  /etc/resolv.conf does not prematurely end the script.  This keeps dhclient
  from looping infinitely when this is the case.  Thanks to a patch from
  Martin Blapp.

- A patch from Bill Stephens was applied which resolves a problem with lease
  expiry times in failover configurations.

- A memory leak in configuration parsing was closed thanks to a patch from
  Steve G.

- The function which discovers interfaces will now skip non-broadcast or
  point-to-point interfaces, thanks to a patch from David Brownlee.

- Options not yet known by the dhcpd or dhclient have had their names
  changed such that they do not contain # symbols, in case they should ever
  appear in a lease file.  An option that might have been named "#144" is
  now "unknown-144".

- Another patch from Bill Stephens which allows the ping-check timeout to
  be configured as 'ping-timeout'.  Defaults to 1.

			Changes since 3.0.1rc10

- Potential buffer overflows in minires repaired.

- A change to the linux client script to use /bin/bash, since /bin/sh may
  not be bash.

- Some missing va_end cleanups thanks to a patch from Thomas Klausner.

- A correction of boolean parsing syntax validation - some illegal syntaxes
  that worked before are now detected and produce errs, some legal syntaxes
  that errored before will now work properly.

- Some search-and-replace errors that caused some options to change their
  names was repaired.

- Shu-min Chang of the Intel corporation has contributed a perl script and
  module that converts the MS NT4 DHCP configuration to a ISC DHCP3
  configuration file.

- Applied the remainder of the dhcpctl memory leak patch provided by Bill
  Squier at ReefEdge, Inc.  (groo@reefedge.com).

- Missing non-optional failover peer configurations will now result in a soft
  error rather than a null dereference.

			Changes since 3.0.1rc9

- A format string was corrected to fix compiler warnings.

- A number of spelling corrections were made in the man pages.

- The dhclient.conf.5 man page was changed to refer to do-forward-updates
  rather than a configuration option that doesn't exist.

- A FreeBSD-specific bug in the interface removal handling was fixed.

- A Linux-specific Token Ring detection problem was fixed.

- Hashes removed from as-yet-unknown agent options, having those options
  appear in reality before we know about them will no longer produce
  self-corrupting lease databases.

- dhclient will use the proper port numbers now when using the -g option.

- A order-of-operations bug with 2 match clauses in 1 class statement is
  fixed thanks to a patch from Andrew Matheson.

- Compilation problems on Solaris were fixed.

- Compilation problems when built with DEBUG or DEBUG_PACKET were repaired.

- A fix to the dhcp ack process which makes certain group options will be
  included in the first DHCPOFFER message was made thanks to a patch from
  Ling Gou.

- A few memory leaks were repaired thanks to patches from Bill Squier at
  ReefEdge, Inc.  (groo@reefedge.com).

- A fix for shared-networks that sometimes give clients options for the
  wrong subnets (in particular, 'option routers') was applied, thanks to
  Ted Lemon for the patch.

- Omshell's handling of dotted octets as values was changed such that dots
  one after the other produce zero values in the integer string.

			Changes since 3.0.1rc8

- Fix a format string vulnerability in the server that could lead to a
  remote root compromise (discovered by NGSEC Research Team, www.ngsec.com).

- Add additional support for NetBSD/sparc64.

- Fix a bug in the command-line parsing of the client.  Also, resolve
  a memory leak.

- Add better support for shells other than bash in the Linux client
  script.

- Various build fixes for modern versions of FreeBSD and Linux.

- Fix a bad bounds check when printing binding state names.

- Clarify documentation about fixed-address and multiple addresses.

- Fix a typo in the authoritative error message.

- Make a log entry when we can't write a billing class.

- Use conversion targets that are the right size on all architectures.

- Increment the hop count when relaying.

- Log a message when lease state is changed through OMAPI.

- Don't rerun the shared_network when evaluating the pool.

- Fix a reversed test in the parser.

- Change the type of rbuf_max.

- Make FTS_LAST a manifest constant to quiet warnings.

			Changes since 3.0.1rc7

- Fix two compiler warnings that are generated when compiling on Solaris
  with gcc.   These stop the build, even though they weren't actually
  errors, because we prefer that our builds generate no warnings.

			Changes since 3.0.1rc6

- Don't allow a lease that's in the EXPIRED, RELEASED or RESET state
  to be renewed.

- Implement lease stealing for cases where the primary has fewer leases
  than the secondary, as called for by the standard.

- Add a fudge factor to the lease expiry acceptance code, (suggested
  by Kevin Miller of CMU).

- Fix a bug in permit_list_match that made it much too willing to say
  that two permit lists matched.

- Unless DEBUG_DNS_UPDATES is defined, print more user-friendly (and
  also more compact) messages about DNS updates.

- Fix a bug in generating wire-format domain names for the FQDN option.

- Fix a bug where the FQDN option would not be returned if the client
  requested it, contrary to the standard.

- On Darwin, use the FreeBSD DHCP client script.

- On NetBSD/sparc, don't check for casting warnings.

- Add a flag in the DHCP client to disable updating the client's A
  record when sending an FQDN option indicating that the client is
  going to update its A record.

- In the client, don't attempt a DNS update until one second after
  configuring the new IP address, and if the update times out, keep
  trying until a response, positive or negative, is received from the
  DNS server.

- Fix an uninitialized memory bug in the DHCP client.

- Apply some FreeBSD-specific bug fixes suggested by Murray Stokely.

- Fix a bug in ns_parserr(), where it was returning the wrong sort
  of result code in some cases (suggested by Ben Harris of the
  NetBSD project).

- Fix a bug in is_identifier(), where it was checking against EOF
  instead of the END_OF_FILE token (also suggested by Ben Harris).

- Fix a bug where if an option universe contained no options, the
  DHCP server could dump core (Walter Steiner).

- Fix a bug in the handling of encapsulated options.

- Fix a bug that prevented NWIP suboptions from being processed.

- Delete the FTS_BOOTP and FTS_RESERVED states and implement them
  as modifier flags to the FTS_ACTIVE state, as called for in the
  failover protocol standard.

- Fix bugs in the pool merging code that resulted in references and
  dereferences of null pointers.   This bug had no impact unless the
  POINTER_DEBUG flag was defined.

- In the server, added a do-forward-updates flag that can be used to
  disable forward updates in all cases, so that sites that want the
  clients to take sole responsibility for updating their A record can
  do so.

- Make it possible to disable optimization of PTR record updates.

			Changes since 3.0.1rc5

- Include some new documentation and changes provided by Karl Auer.

- Add a workaround for some Lexmark printers that send a double-NUL-
  terminated host-name option, which would break DNS updates.

- Fix an off-by-one error in the MAC-address checking code for
  DHCPRELEASE that was added in 3.0.1rc5.

- Fix a bug where client-specific information was not being discarded
  from the lease when it expired or was released, resulting in
  problems if the lease was reallocated to a different client.

- If more than one allocation pool is specified that has the same set
  of constraints as another allocation pool on the same shared
  network, merge the two pools.

- Don't print an error in fallback_discard, since this just causes
  confusion and does not appear to be helping to encourage anyone to
  fix this bug.

			Changes since 3.0.1rc4

- Fix a bug that would cause the DHCP server to spin if asked to parse
  a certain kind of incorrect statement.

- Fix a related bug that would prevent an error from being reported in
  the same case.

- Additional documentation.

- Make sure that the hardware address matches the lease when
  processing a DHCPRELEASE message.

			Changes since 3.0.1rc3

- A minor bug fix in the arguments to a logging function call.
- Documentation update for dhcpd.conf.

		        Changes since 3.0.1rc2

- Allow the primary to send a POOLREQ message.   This isn't what the current
  failover draft says to do, so we may have to back it out if I can't get the
  authors to relent, but the scheme for balancing that's specified in the
  current draft seems needlessly hairy, so I'm floating a trial balloon.
  The rc1 code did not implement the method described in the draft either.

		        Changes since 3.0.1rc1

- Treat NXDOMAIN and NXRRSET as success when we are trying to delete a
  domain or RRSET.   This allows the DHCP server to forget about a name
  it added to the DNS once it's been removed, even if the DHCP server
  wasn't the one that removed it.

- Install defaults for failover maximum outstanding updates and maximum
  silent time.   This prevents problems that might occur if these values
  were not configured.

- Don't do DDNS deletes if ddns-update-style is none.

- Return relay agent information options in DHCPNAK.   This prevents DHCPNAK
  messages from being dropped when the relay agent information option contains
  routing information.

- Fix a problem where coming up in recover wouldn't result in an update
  request being sent.

- Add some more chatty messages when we start a recovery update and when it's
  done.

- Fix a possible problem where some state might have been left around
  after the peer lost contact and regained contact about how many updates
  were pending.

- Don't nix a lease update because of a lease conflict.   This test has
  never (as far as I know) prevented a mistake, and it appears to cause
  problems with failover.

- Add support in rc history code for keeping a selective history, rather
  than a history of all references and dereferences.   This code is only used
  when extensive additional debugging is enabled.

		           Changes since 3.0

- Make allocators for hash tables.   As a side effect, this fixes a memory
  smash in the subclass allocation code.

- Fix a small bug in omshell where if you try to close an object when
  no object is open, it dumps core.

- Fix an obscure coredump that could occur on shutdown.

- Fix a bug in the recording of host declaration rubouts in the lease file.

- Fix two potential spins in the host deletion code.

- Fix a core dump that would happen if an application tried to update
  a host object attribute with a null value.

		Changes since 3.0 Release Candidate 12

- Fix a memory leak in the evaluation code.

- Fix an obscure core dump.

- Print a couple of new warnings when parsing the configuration file
  when crucial information is left out.

- Log "no free leases" as an error.

- Documentation updates.

		Changes since 3.0 Release Candidate 11

- Always return a subnet selection option if one is sent.

- Fix a warning that was being printed because an automatic data
  structure wasn't zeroed.

- Fix some failover state transitions that were being handled
  incorrectly.

- When supersede_lease is called on a lease whose end time has already
  expired, but for which a state transition has not yet been done, do
  a state transition.   This fixes the case where if the secondary
  allocated a lease to a client and the lease "expired" while the
  secondary was in partner-down, no expiry event would actually
  happen, so the lease would remain active until the primary was
  restarted.

		Changes since 3.0 Release Candidate 10

- Fix a bug that was preventing released leases from changing state
  in failover-enabled pools.

- Fix a core dump in the client identifier finder code (for host
  declarations).

- Finish fixing a bug where bogus data would sometimes get logged to
  the dhclient.leases file because it was opened as descriptor 2.

- Fix the Linux dhclient-script according to suggestions made by
  several people on the dhcp-client mailing list.

- Log successful DNS updates at LOG_INFO, not LOG_ERROR.

- Print an error message and refuse to run if a failover peer is
  defined but not referenced by any pools.

- Correct a confusing error message in failover.

		Changes since 3.0 Release Candidate 9

- Fix a bug in lease allocation for Dynamic BOOTP clients.

	  Changes since 3.0 Release Candidate 8 Patchlevel 2

- Fix a bug that prevented update-static-leases from working.

- Document failover-state OMAPI object.

- Fix a compilation error on SunOS 4.

	  Changes since 3.0 Release Candidate 8 Patchlevel 1

- Fix a parsing bug that broke dns updates (both interim and ad-hoc).
  This was introduced in rc8pl1 as an unintended result of the memory
  leakage fixes that were in pl1.

- Fix a long-standing bug where the server would record that an update
  had been done for a client with no name, even though no update had
  been done, and then when the client's lease expired the deletion of
  that nonexistant record would time out because the name was the null
  string. 

- Clean up the omshell, dhcpctl and omapi man pages a bit.

		Changes since 3.0 Release Candidate 8

- Fix a bug that could cause the DHCP server to spin if
  one-lease-per-client was enabled.

- Fix a bug that was causing core dumps on BSD/os in the presence of
  malformed packets.

- In partner-down state, don't restrict lease lengths to MCLT.

- On the failover secondary, record the MCLT received from the primary
  so that if we come up without a connection to the primary we don't
  wind up giving out zero-length leases.

- Fix some compilation problems on BSD/os.

- Fix a bunch of memory leaks.

- Fix a couple of bugs in the option printer.

- Fix an obscure error reporting bug in the dns update code, and also
  make the message clearer when a key algorithm isn't supported.

- Fix a bug in the tracing code that prevented trace runs that used
  tcp connections from being played back.

- Add some additional debugging capability for catching memory leaks
  on exit.

- Make the client release the lease correctly on shutdown.

- Add some configurability to the build system.

- Install omshell manual page in man1, not man8.

- Craig Gwydir sent in a patch that fixes a long-standing bug in the
  DHCP client that could cause core dumps, but that for some reason
  hadn't been noticed until now.

		Changes since 3.0 Release Candidate 7

- Fix a bug in failover where we weren't sending updates after a
  transition from communications-interrupted to normal.

- Handle expired/released/reset -> free transition according to the
  protocol specification (this works - the other way not only wasn't
  conformant, but also didn't work).

- Add a control object in both client and server that allows either
  daemon to be shut down cleanly.

- When writing a lease, if we run out of disk space, shut down the
  output file and insist on writing a new one before proceeding.

- In the server, if the OMAPI listener port is occupied, keep trying
  to get it, rather than simply giving up and exiting.

- Support fetching variables from leases and also updating and adding
  variables to leases via OMAPI.

- If two failover peers have wildly different clocks, refuse to start
  doing failover.

- Fix a bug in the DNS update code that could cause core dumps when
  running on alpha processors.

- Fixed a bug in ddns updates for static lease entries, thanks to a
  patch from Andrey M Linkevitch.

- Add support for Darwin/MacOS X

- Install omshell (including new documentation).

- Support DNS updates in the client (this is a very obscure feature
  that most DHCP client users probably will not be able to use).

- Somewhat cleaner status logging in the client.

- Make OMAPI key naming syntax compatible with the way keys are
  actually named (key names are domain names).

- Fix a bug in the lease file writer.

- Install DHCP ISC headers in a different place than BIND 9 ISC
  headers, to avoid causing trouble in BIND 9 builds.

- Don't send updates for attributes on an object when the attributes
  haven't changed.   Support deleting attributes on remote objects.

- Fix a number of bugs in omshell, and add the unset and refresh
  statements.

- Handle disconnects in OMAPI a little bit more intelligently (so that
  the caller gets ECONNRESET instead of EINVAL).

- Fix a bunch of bugs in the handling of clients that have existing
  leases when the try to renew their leases while failover is
  operating.

		Changes since 3.0 Release Candidate 6

- Fix a core dump that could happen when processing a DHCPREQUEST from
  a client that had a host declaration that contained both a
  fixed-address declaration and a dhcp-client-identifier option
  declaration, if the client identifier was longer than nine bytes.

- Fix a memory leak that could happen in certain obscure cases when
  using omapi to manipulate leases.

- Fix some bugs and omissions in omshell.


		Changes since 3.0 Release Candidate 5

- Fix a bug in omapi_object_dereference that prevented objects in
  chains from having their reference counts decreased on dereference.

- Fix a bug in omapi_object_dereference that would prevent object
  chains from being freed upon removal of the last reference external
  to the chain.

- Fix a number of other memory leaks in the OMAPI protocol subsystem.

- Add code in the OMAPI protocol handler to trace memory leakage.

- Clean up the memory allocation/reference history printer.

- Support input of dotted quads and colon-separated hex lists as
  attribute values in omshell.

- Fix a typo in the Linux interface discovery code.

- Conditionalize a piece of trace code that wasn't conditional.

		Changes since 3.0 Release Candidate 4

- Fix a bug that would prevent leases from being abandoned properly on
  DHCPDECLINE.

- Fix failover peer OMAPI support.

- In failover, correctly handle expiration of leases.   Previously,
  leases would never be reclaimed because they couldn't make the
  transition from EXPIRED to FREE.

- Fix some broken failover state transitions.

- Documentation fixes.

- Take out an unnecessary check in DHCP relay agent information option
  stashing code that was preventing REBINDING clients from rebinding.

- Prevent failover peers from allocating leases in DHCPREQUEST
  processing if the lease belongs to the other server.

- Record server version in lease file introductory comment.

- Correctly report connection errors in OMAPI and failover.

- Make authentication signature algorithm name comparisons in OMAPI
  case-insensitive.

- Fix compile problem on SunOS 4.x

- If a signature algorithm is not terminated with '.', terminate it so
  that comparisons between fully-qualified names will work
  consistently.

- Different SIOCGIFCONF probe code, may "fix" problem on some Linux
  systems with the probe not working correctly.

- Don't allow user to type omapi key on command line of omshell.

		Changes since 3.0 Release Candidate 3

- Do lease billing on startup in a way that I *think* will finally do
  the billing correctly - the previous method could overbill as a
  result of duplicate leases.

- Document OMAPI server objects.

	  Changes since 3.0 Release Candidate 2 Patchlevel 1

- Fix some problems in the DDNS update code.   Thanks to Albert
  Herranz for figuring out the main problem.

- Fix some reference counting errors on host entries that were causing
  core dumps.

- Fix a byte-swap bug in the token ring code, thanks to Jochen
  Friedrich.

- Fix a bug in lease billing, thanks to Jonas Bulow.

		Changes since 3.0 Release Candidate 2

- Change the conditions under which a DHCPRELEASE is actually
  committed to be consistent with lease binding states rather than
  using the lease end time.   This may fix some problems with the
  billing class code.

- Fix a bug where lease updates would fail on Digital Unix (and maybe
  others) because malloc was called with a size of zero.

- Fix a core dump that happens when the DHCP server can't create its
  trace file.

	  Changes since 3.0 Release Candidate 1 Patchlevel 1

- Fix the dhcp_failover_put_message to not attempt to allocate a
  zero-length buffer.   Some versions of malloc() fail if you try to
  allocate a zero-length buffer, and this was causing problems on,
  e.g., Digital Unix.

- Fix a case where the failover code was printing an error message
  when no error had occurred.

- Fix a problem where when a server went down and back up again, the
  peer would not see a state transition and so would stay in the
  non-communicating state.

- Be smart about going into recover_wait.

- Fix a problem in the failover implementation where peers would fail
  to come into sync if interrupted in the RECOVER state.   This could
  have been the cause of some problems people have reported recently.

- Fix a problem with billing classes where they would not be unbilled
  when the client lease expired.

- If select fails, figure out which descriptor is bad, and cut it out
  of the I/O loop.   This prevents a potentially nasty spin.  I
  haven't heard any report it in a while, but it came up consistently
  in testing.

- Fix a bug in the relay agent where if you specified interfaces on
  the command line, it would fail.

- Fix a couple of small bugs in the omapi connection object (no known
  user impact).

- Add the missing 3.0 Beta 1 lease conversion script.

- Read dhcp client script hooks if they exist, rather than only if
  they're executable.

		Changes since 3.0 Release Candidate 1

- Fix a memory smash that happens when fixed-address leases are used.
  ANY SITE AT WHICH FIXED-ADDRESS STATEMENTS ARE BEING USED SHOULD
  UPGRADE IMMEDIATELY.   This has been a long-standing bug - thanks to
  Alvise Nobile for discovering it and helping me to find it!

- Fix a small bug in binary-to-ascii, thanks to H. Peter Anvin of
  Transmeta.

- There is a known problem with the DHCP server doing failover on
  Compaq Alpha systems.   This patchlevel is not a release candidate
  because of this bug.   The bug should be straightforward to fix, so
  a new release candidate is expected shortly.

- There is a known problem in the DDNS update code that is probably a
  bug, and is not, as far as we know, fixed in this patchlevel.

		Changes since 3.0 Beta 2 Patchlevel 24

- Went over problematic failover state transitions and made them all
  work, so that failover should now much less fragile.

- Add some dhcpctl and omapi documentation

- Fix compile errors when compiling with unusual predefines.

- Make Token Ring work on Linux 2.4

- Fix the Digital Unix BPF_WORDALIGN bug.

- Fix some dhcp client documentation errors.

- Update some parts of the README file.

- Support GCC on SCO.

	        Changes since 3.0 Beta 2 Patchlevel 23

- Fix a bug in the DNS update code where a status code was not being
  checked.   This may have been causing core dumps.

- When parsing the lease file, if a lease declaration includes a
  billing class statement, and the lease already has a billing class,
  unbill the old class.

- When processing failover transactions, where acks will be deferred,
  process the state transition immediately.

-  Don't try to use the new SIOCGIFCONF buffer size detection code on
   Linux 2.0, which doesn't provide this functionality.

- Apply a patch suggested by Tuan Uong for a problem in dlpi.c.

- Fix a problem in using the which command in the configure script.

- Fix a parse error in the client when setting up an omapi listener.

- Document the -n and -g flags to the client.

- Make sure there is always a stdin and stdout on startup.   This
  prevents shell scripts from accidentally writing error messages into
  configuration files that happen to be opened as stderr.

- If an interface is removed, the client will now notice that it is
  gone rather than spinning.   This has only been tested on NetBSD.

- The client will attempt to get an address even if it can't create a
  lease file.

- Don't overwrite tracefiles.

- Fix some memory allocation bugs in failover.

	        Changes since 3.0 Beta 2 Patchlevel 22

- Apply some patches suggested by Cyrille Lefevre, who is maintaining
  the FreeBSD ISC DHCP Distribution port.

- Fix a core dump in DHCPRELEASE.

	        Changes since 3.0 Beta 2 Patchlevel 21

- This time for sure: fix the spin described in the changes for pl20.

	        Changes since 3.0 Beta 2 Patchlevel 20

- Fix a problem with Linux detecting large numbers of interfaces (Ben)

- Fix a memory smash in the quotify code, which was introduced in
  pl19.

- Actually fix the spin described in the changes for pl20.   The
  previous fix only partially fixed the problem - enough to get it
  past the regression test.

	        Changes since 3.0 Beta 2 Patchlevel 19

- Fix a bug that could cause the server to abort if compiled with
  POINTER_DEBUG enabled.

- Fix a bug that could cause the server to spin when responding to a
  DHCPREQUEST.

- Apply Joost Mulders' suggested patches for DLPI on x86.

- Support NUL characters in quoted strings.

- Install unformatted man pages on SunOS.

	        Changes since 3.0 Beta 2 Patchlevel 18

- Allow the server to be placed in partner-down state using OMAPI.
  (Damien Neil)

- Implement omshell, which can be used to do arbitrary things to the
  server (in theory). (Damien Neil)

- Fix a case where if a client had two different leases the server could
  actually dereference the second one when it hadn't been referenced,
  leading to memory corruption and a core dump. (James Brister)

- Fix a case where a client could request the address of another client's
  lease, but find_lease wouldn't detect that the other client had it, and
  would attempt to allocate it to the client, resulting in a lease conflict
  message.

- Fix a case where a client with more than one client identifier could be
  given a lease where the hardware address was correct but the client
  identifier was not, resulting in a lease conflict message.

- Fix a problem where the server could write out a colon-separated
  hex list as a value for a variable, which would then not parse.
  The fix is to always write strings as quoted strings, with any
  non-printable characters quoted as octal escape sequences.   So
  a file written the old way still won't work, but new files written
  this way will work.

- Fix documentation for sending non-standard options.

- Use unparsable names for unknown options.    WARNING: this will
  break any configuration files that use the option-nnn convention.
  If you want to continue to use this convention for some options,
  please be sure to write a definition, like this:

  option option-nnn code nnn = string;

  You can use a descriptive name instead of option-nnn if you like.

- Fix a problem where we would see a DHCPDISCOVER/DHCPOFFER/
  DHCPREQUEST/DHCPACK/DHCPREQUEST/DHCPNAK sequence.   This was the
  result of a deceptively silly bug in supersede_lease.

- Fix client script exit status check, according to a fix supplied by
  Hermann Lauer.

- Fix an endianness bug in the tracefile support, regarding ICMP
  messages.

- Fix a bug in the client where the medium would not work correctly if
  it contained quoted strings.

		       ** there was no pl17 **

	        Changes since 3.0 Beta 2 Patchlevel 16

- Add support for transaction tracing.   This allows the state of the
  DHCP server on startup, and all the subsequent transactions, to be
  recorded in a file which can then be played back to reproduce the
  behaviour of the DHCP server.   This can be used to quickly
  reproduce bugs that cause core dumps or corruption, and also for
  tracking down memory leaks.

- Incorporate some bug fixes provided by Joost Mulders for the DLPI
  package which should clear up problems people have been seeing on
  Solaris.

- Fix bugs in the handling of options stored as linked lists (agent
  options, fqdn options and nwip options) that could cause memory
  corruption and core dumps.

- Fix a bug in DHCPREQUEST handling that resulted in DHCPNAK messages
  not being send in some cases when they were needed.

- Make the lease structure somewhat more compact.

- Make initial failover startup *much* faster.   This was researched
  and implemented by Damien Neil.

- Add a --version flag to all executables, which prints the program
  name and version to standard output.

- Don't rewrite the lease file every thousand leases.

- A bug in nit.c for older SunOS machines was fixed by a patch sent in
  by Takeshi Hagiwara.

- Fix a memory corruption bug in the DHCP client.

- Lots of documentation updates.

- Add a feature allowing environment variables to be passed to the
  DHCP client script on the DHCP client command line.

- Fix client medium support, which had been broken for some time.

- Fix a bug in the DHCP client initial startup backoff interval, which
  would cause two DHCPDISCOVERS to be sent back-to-back on startup.


	        Changes since 3.0 Beta 2 Patchlevel 15

- Some documentation tweaks.

- Maybe fix a problem in the DLPI code.

- Fix some error code space inconsistencies in ddns update code.

- Support relay agents that intercept unicast DHCP messages to stuff
  agent options into them.

- Fix a small memory leak in the relay agent option support code.

- Fix a core dump that would occur if a packet was sent with no
  options.

	        Changes since 3.0 Beta 2 Patchlevel 14

- Finish fixing a long-standing bug in the agent options code.   This
  was causing core dumps and failing to operate correctly - in
  particular, agent option stashing wasn't working.   Agent option
  stashing should now be working, meaning that agent options can be
  used in class statements to control address allocation.

- Fix up documentation.

- Fix a couple of small memory leaks that would have added up
  significantly in a high-demand situation.

- Add a log-facility configuration parameter.

- Fix a compile error on some older operating systems.

- Add the ability in the client to execute certain statements before
  transmitting packets to the server.   Handy for debugging; not much
  practical use otherwise.

- Don't send faked-out giaddr when renewing or bound - again, useful
  for debugging.

	        Changes since 3.0 Beta 2 Patchlevel 13

- Fixed a problem where the fqdn decoder would sometimes try to store
  an option with an (unsigned) negative length, resulting in a core
  dump on some systems.

- Work around the Win98 DHCP client, which NUL-terminates the FQDN
  option.

- Work around Win98 and Win2k clients that will claim they want to do
  the update even when they don't have any way to do it.

- Fix some log messages that can be printed when failover is operating
  that were not printing enough information.

- It was possible for a DHCPDISCOVER to get an allocation even when
  the state machine said the server shouldn't be responding.

- Don't load balance DHCPREQUESTs from clients in RENEWING and
  REBINDING, since in RENEWING, if we heard it, it's for us, and in
  REBINDING, the client wouldn't have got to REBINDING if its primary
  were answering.

- When we get a bogus state lease binding state transition, don't do
  the transition.
  

	        Changes since 3.0 Beta 2 Patchlevel 12

- Fixed a couple of silly compile errors.

		Changes since 3.0 Beta 2 Patchlevel 11

- Albert Herranz tracked down and fixed a subtle bug in the base64
  decoder that would prevent any key with an 'x' in its base64
  representation from working correctly.

- Thanks to Chris Cheney and Michael Sanders, we have a fix for the
  hang that they both spotted in the DHCP server - when
  one-lease-per-client was set, the code to release the "other" lease
  could spin.

- Fix a problem with alignment of the input buffer in bpf in cases
  where two packets arrive in the same bpf read.

- Fix a problem where the relay agent would crash if you specified an
  interface name on the command line.

- Add the ability to conditionalize client behaviour based on the
  client state.

- Add support for the FQDN option, and added support for a new way of
  doing ddns updates (ddns update style interim) that allows more than
  one DHCP server to update the DNS for the same network(s).   This
  was implemented by Damien Neil with some additional functionality
  added by Ted Lemon.

- Damien added a "log" statement, so that the configuration file can
  be made to log debugging information and other information.

- Fixed a bug that caused option buffers not to be terminated with an
  end option.

- Fixed a long-standing bug in the support for option spaces where the
  options are stored as an ordered list rather than in a hash table,
  which could theoretically result in memory pool corruption.

- Prevent hardware declarations with no actual hardware address from
  being written as something unparsable, and behave correctly in the
  face of a null hardware address on input.

- Allow key names to be FQDNs, and qualify the algorithm name if it is
  specified unqualified.

- Modify the DDNS update code so that it never prints the "resolver
  failed" message, but instead says *why* the resolver failed.

- Officially support the subnet selection option, which now has an
  RFC.

- Fix a build bug on MacOS X.

- Allow administrator to disable ping checking.

- Clean up dhcpd.conf documentation and add more information about how
  it works.

		Changes since 3.0 Beta 2 Patchlevel 10

- Fix a bug introduced during debugging (!) and accidentally committed
  to CVS.

		Changes since 3.0 Beta 2 Patchlevel 9

- Fix DHCP client handling of vendor encapsulated options.

- Fix a bug in the handling of relay agent information options introduced
  in patchlevel 9.

- Stash agent options on client leases by default, and use the stashed
  options at renewal time.

- Add the ability to test the client's binding state in the client
  configuration language.

- Fix a core dump in the DNS update code.

- Fix some expression evaluation bugs that were causing updates to be
  done when no client hostname was received.

- Fix expression evaluation debugging printfs.

- Teach pretty_print_option to print options in option spaces other than
  the DHCP option space.

- Add a warning message if the RHS of a not is not boolean.

- Never select for more than a day, because some implementations of
  select will just fail if the timeout is too long (!).

- Fix a case where a DHCPDISCOVER from an unknown network would be
  silently dropped.

- Fix a bug where if a client requested an IP address for which a different
  client had the lease, the DHCP server would reallocate it anyway.

- Fix the DNS update code so that if the client changes its name, the DNS
  will be correctly updated.

		Changes since 3.0 Beta 2 Patchlevel 8

- Oops, there was another subtle math error in the header-length
  bounds-checking.

		Changes since 3.0 Beta 2 Patchlevel 7

- Oops, forgot to byte-swap udp header length before bounds-checking it.

		Changes since 3.0 Beta 2 Patchlevel 6

- Fix a possible DoS attack where a client could cause the checksummer
  to dump core.   This was a read, not a write, so it shouldn't be
  possible to exploit it any further than that.

- Implement client- and server-side support for using the Client FQDN
  option.

- Support for other option spaces in the client has been added.   This
  means that it is now possible to define a vendor option space on the
  client, request options in that space from the server (which must
  define the same option space), and then use those options in the
  client.   This also allows NWIP and Client FQDN options to be used
  meaningfully.

- Add object initializer support.   This means that objects can now be
  initialized to something other than all-zeros when allocated, which
  makes, e.g., the interface object support code a little more robust.

- Fix an off-by-one bug in the host stuffer.   This was causing host
  deletes not the work, and may also have been causing OMAPI
  connections to get dropped.   Thanks to James Brister for tracking
  this one down!

- Fixed a core dump in the interface discovery code that is triggered
  when there is no subnet declaration for an interface, but the server
  decides to continue running.   Thanks to Shane Kerr for tracking
  down and fixing this problem.

		Changes since 3.0 Beta 2 Patchlevel 5

- Fix a bug in the recent enhancement to the interface discovery code
  to support arbitrary-length interface lists.

- Support NUL-terminated DHCP options when initializing client-script
  environment.

- Fix suffix operator.

- Fix NetWare/IP option parsing.

- Better error/status checking in dhcpctl initialization and omapi
  connection code.

- Fix a potential memory smash in dhcpctl code.

- Fix SunOS4 and (maybe) Ultrix builds.

- Fix a bug where a certain sort of incoming packet could cause a core
  dump on Solaris (and probably elsewhere).

- Add some more safety checks in error logging code.

- Add support for ISC_R_INCOMPLETE in OMAPI protocol connection code.

- Fix relay agent so that if an interface is specified on the command
  line, the relay agent does not dump core.

- Fix class matching so that match if can be combined with match or
  spawn with.

- Do not allow spurious leases in the lease database to introduce
  potentially bogus leases into the in-memory database.

- Fix a byte-order problem in the client hardware address type code
  for OMAPI.

- Be slightly less picky about what sort of hardware addresses OMAPI
  can install in host declarations.

		Changes since 3.0 Beta 2 Patchlevel 4

- Incorporated Peter Marschall's proposed change to array/record
  parsing, which allows things like the slp-agent option to be encoded
  correctly.   Thanks very much to Peter for taking the initiative to
  do this, and for doing such a careful job of it (e.g., updating the
  comments)!

- Added an encoding for the slp-agent option.   :')

- Fixed SunOS 4 build.  Thanks to Robert Elz for responding to my
  request for help on this with patches!

- Incorporated a change that should fix a problem reported by Philippe
  Jumelle where when the network connection between two servers is
  lost, they never reconnect.

- Fix client script files other than that for NetBSD to actually use
  make_resolv_conf as documented in the manual page.

- Fix a bug in the packet handling code that could result in a core
  dump.

- Fix a bug in the bootp code where responses on the local net would
  be sent to the wrong MAC address.   Thanks to Jerry Schave for
  catching this one.

		Changes since 3.0 Beta 2 Patchlevel 3

- In the DHCP client, execute client statements prior to using the values
  of options, so that the client configuration can overridden, e.g., the
  lease renewal time.

- Fix a reference counting error that would result in very reproducible
  failures in updates, as well as occasional core dumps, if a zone was
  declared without a key.

- Fix some Linux 2.0 compilation problems.

- Fix a bug in scope evaluation during execution of "on" statements that
  caused values not to be recorded on leases.

- If the dhcp-max-message-size option is specified in scope, and the
  client didn't send this option, use the one specified in scope to
  determine the maximum size of the response.

		Changes since 3.0 Beta 2 Patchlevel 2

- Fix a case where spawning subclasses were being allocated
  incorrectly, resulting in a core dump.

- Fix a case where the DHCP server might inappropriately NAK a
  RENEWING client.

- Fix a place dhcprequest() where static leases could leak.

- Include memory.h in omapip_p.h so that we don't get warnings about
  using memcmp().

		Changes since 3.0 Beta 2 Patchlevel 1

- Notice when SIOCFIGCONF returns more data than fit in the buffer -
  allocate a larger buffer, and retry.   Thanks to Greg Fausak for
  pointing this out.

- In the server, if no interfaces were configured, report an error and
  exit.

- Don't ever record a state of 'startup'.

- Don't try to evaluate the local failover binding address if none was
  specified.   Thanks to Joseph Breu for finding this.