#ifndef lint
static char copyright[] =
-"$Id: confpars.c,v 1.31 1996/08/30 23:39:37 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium. All rights reserved.\n";
+"$Id: confpars.c,v 1.32 1996/09/02 21:16:25 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium. All rights reserved.\n";
#endif /* not lint */
#include "dhcpd.h"
int token;
int declaration = 0;
- new_parse (_PATH_DHCPD_CONF);
+ new_parse (path_dhcpd_conf);
/* Set up the initial dhcp option universe. */
initialize_universes ();
root_group.bootp_lease_cutoff = MAX_TIME;
root_group.boot_unknown_clients = 1;
- if ((cfile = fopen (_PATH_DHCPD_CONF, "r")) == NULL)
- error ("Can't open %s: %m", _PATH_DHCPD_CONF);
+ if ((cfile = fopen (path_dhcpd_conf, "r")) == NULL)
+ error ("Can't open %s: %m", path_dhcpd_conf);
do {
token = peek_token (&val, cfile);
if (token == EOF)
char *val;
int token;
- new_parse (_PATH_DHCPD_DB);
+ new_parse (path_dhcpd_db);
/* Open the lease file. If we can't open it, fail. The reason
for this is that although on initial startup, the absence of
human has corrected the database problem, then we are left
thinking that no leases have been assigned to anybody, which
could create severe network chaos. */
- if ((cfile = fopen (_PATH_DHCPD_DB, "r")) == NULL)
+ if ((cfile = fopen (path_dhcpd_db, "r")) == NULL)
error ("Can't open lease database %s: %m -- %s",
- _PATH_DHCPD_DB,
+ path_dhcpd_db,
"check for failed database rewrite attempt!");
do {
token = next_token (&val, cfile);
#ifndef lint
static char copyright[] =
-"$Id: db.c,v 1.7 1996/08/27 09:42:26 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium. All rights reserved.\n";
+"$Id: db.c,v 1.8 1996/09/02 21:16:24 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium. All rights reserved.\n";
#endif /* not lint */
#include "dhcpd.h"
/* Make a temporary lease file... */
time (&t);
- sprintf (newfname, "%s.%d", _PATH_DHCPD_DB, (int) (t & 32767));
+ sprintf (newfname, "%s.%d", path_dhcpd_db, (int) (t & 32767));
if ((db_file = fopen (newfname, "w")) == NULL) {
error ("Can't start new lease file: %m");
}
write_leases ();
/* Get the old database out of the way... */
- sprintf (backfname, "%s~", _PATH_DHCPD_DB);
+ sprintf (backfname, "%s~", path_dhcpd_db);
if (unlink (backfname) < 0 && errno != ENOENT)
error ("Can't remove old lease database backup %s: %m",
backfname);
- if (link (_PATH_DHCPD_DB, backfname) < 0)
+ if (link (path_dhcpd_db, backfname) < 0)
error ("Can't backup lease database %s to %s: %m",
- _PATH_DHCPD_DB, backfname);
+ path_dhcpd_db, backfname);
/* Move in the new file... */
- if (rename (newfname, _PATH_DHCPD_DB) < 0)
+ if (rename (newfname, path_dhcpd_db) < 0)
error ("Can't install new lease database %s to %s: %m",
- newfname, _PATH_DHCPD_DB);
+ newfname, path_dhcpd_db);
counting = 1;
}
.B -d
]
[
+.B -cf
+.I config-file
+]
+[
+.B -lf
+.I lease-file
+]
+[
.I if0
[
.I ...ifN
reliable or otherwise cannot be used. Normally, dhcpd will log all
output using the syslog(3) function with the log facility set to
LOG_DAEMON.
+.PP
+Dhcpd can be made to use an alternate configuration file with the
+.B -cf
+flag, or an alternate lease file with the
+.B -lf
+flag. Because of the importance of using the same lease database at
+all times when running dhcpd in production, these options should be
+used \fBonly\fR for testing lease files or database files in a
+non-production environment.
.SH CONFIGURATION
The syntax of the dhcpd.conf(8) file is discussed seperately. This
section should be used as an overview of the configuration process,
dhcpd - Dynamic Host Configuration Protocol Server
S\bSY\bYN\bNO\bOP\bPS\bSI\bIS\bS
- d\bdh\bhc\bcp\bpd\bd [ -\b-p\bp _\bp_\bo_\br_\bt ] [ -\b-f\bf ] [ _\bi_\bf_\b0 [ _\b._\b._\b._\bi_\bf_\bN ] ]
+ d\bdh\bhc\bcp\bpd\bd [ -\b-p\bp _\bp_\bo_\br_\bt ] [ -\b-f\bf ] [ -\b-d\bd ] [ -\b-c\bcf\bf _\bc_\bo_\bn_\bf_\bi_\bg_\b-_\bf_\bi_\bl_\be ] [ -\b-l\blf\bf
+ _\bl_\be_\ba_\bs_\be_\b-_\bf_\bi_\bl_\be ] [ _\bi_\bf_\b0 [ _\b._\b._\b._\bi_\bf_\bN ] ]
D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
The Internet Software Consortium DHCP Server, dhcpd,
- implements the Dynamic Host Configuration Protocol (DHCP)
- and the Internet Bootstrap Protocol (BOOTP). DHCP allows
- hosts on a TCP/IP network to request and be assigned IP
+ implements the Dynamic Host Configuration Protocol (DHCP)
+ and the Internet Bootstrap Protocol (BOOTP). DHCP allows
+ hosts on a TCP/IP network to request and be assigned IP
addresses, and also to discover information about the net-
- work to which they are attached. BOOTP provides similar
+ work to which they are attached. BOOTP provides similar
functionality, with certain restrictions.
O\bOP\bPE\bER\bRA\bAT\bTI\bIO\bON\bN
- The DHCP protocol allows a host which is unknown to the
- network administrator to be automatically assigned a new
- IP address out of a pool of IP addresses for its network.
+ The DHCP protocol allows a host which is unknown to the
+ network administrator to be automatically assigned a new
+ IP address out of a pool of IP addresses for its network.
In order for this to work, the network administrator allo-
- cates address pools in each subnet and enters them into
+ cates address pools in each subnet and enters them into
the dhcpd.conf(5) file.
- On startup, dhcpd reads the _\bd_\bh_\bc_\bp_\bd_\b._\bc_\bo_\bn_\bf file and stores a
- list of available addresses on each subnet in memory.
+ On startup, dhcpd reads the _\bd_\bh_\bc_\bp_\bd_\b._\bc_\bo_\bn_\bf file and stores a
+ list of available addresses on each subnet in memory.
When a client requests an address using the DHCP protocol,
dhcpd allocates an address for it. Each client is
- assigned a lease, which expires after an amount of time
+ assigned a lease, which expires after an amount of time
chosen by the administrator (by default, one day). Before
- leases expire, the clients to which leases are assigned
+ leases expire, the clients to which leases are assigned
are expected to renew them in order to continue to use the
- addresses. Once a lease has expired, the client to which
- that lease was assigned is no longer permitted to use the
+ addresses. Once a lease has expired, the client to which
+ that lease was assigned is no longer permitted to use the
leased IP address.
In order to keep track of leases across system reboots and
- server restarts, dhcpd keeps a list of leases it has
+ server restarts, dhcpd keeps a list of leases it has
assigned in the dhcpd.leases(5) file. Before dhcpd
- grants a lease to a host, it records the lease in this
- file and makes sure that the contents of the file are
- flushed to disk. This ensures that even in the event of
- a system crash, dhcpd will not forget about a lease that
- it has assigned. On startup, after reading the
- dhcpd.conf file, dhcpd reads the dhcpd.leases file to
+ grants a lease to a host, it records the lease in this
+ file and makes sure that the contents of the file are
+ flushed to disk. This ensures that even in the event of
+ a system crash, dhcpd will not forget about a lease that
+ it has assigned. On startup, after reading the
+ dhcpd.conf file, dhcpd reads the dhcpd.leases file to
refresh its memory about what leases have been assigned.
- New leases are appended to the end of the dhcpd.leases
- file. In order to prevent the file from becoming arbi-
- trarily large, from time to time dhcpd creates a new
- dhcpd.leases file from its in-core lease database. Once
- this file has been written to disk, the old file is
- renamed _\bd_\bh_\bc_\bp_\bd_\b._\bl_\be_\ba_\bs_\be_\bs_\b~, and the new file is renamed
- dhcpd.leases. If the system crashes in the middle of
- this process, whichever dhcpd.leases file remains will
+ New leases are appended to the end of the dhcpd.leases
+ file. In order to prevent the file from becoming arbi-
+ trarily large, from time to time dhcpd creates a new
+ dhcpd.leases file from its in-core lease database. Once
+ this file has been written to disk, the old file is
+ renamed _\bd_\bh_\bc_\bp_\bd_\b._\bl_\be_\ba_\bs_\be_\bs_\b~, and the new file is renamed
+ dhcpd.leases. If the system crashes in the middle of
dhcpd(8) dhcpd(8)
+ this process, whichever dhcpd.leases file remains will
contain all the lease information, so there is no need for
a special crash recovery process.
- BOOTP support is also provided by this server. Unlike
- DHCP, the BOOTP protocol does not provide a protocol for
+ BOOTP support is also provided by this server. Unlike
+ DHCP, the BOOTP protocol does not provide a protocol for
recovering dynamically-assigned addresses once they are no
- longer needed. It is still possible to dynamically
+ longer needed. It is still possible to dynamically
assign addresses to BOOTP clients, but some administrative
- process for reclaiming addresses is required. By
- default, leases are granted to BOOTP clients in perpetu-
+ process for reclaiming addresses is required. By
+ default, leases are granted to BOOTP clients in perpetu-
ity, although the network administrator may set an earlier
- cutoff date or a shorter lease length for BOOTP leases if
+ cutoff date or a shorter lease length for BOOTP leases if
that makes sense.
- BOOTP clients may also be served in the old standard way,
+ BOOTP clients may also be served in the old standard way,
which is to simply provide a declaration in the dhcpd.conf
- file for each BOOTP client, permanently assigning an
+ file for each BOOTP client, permanently assigning an
address to each client.
- Whenever changes are made to the dhcpd.conf file, dhcpd
- must be restarted. To restart dhcpd, send a SIGTERM
- (signal 15) to the process ID contained in
+ Whenever changes are made to the dhcpd.conf file, dhcpd
+ must be restarted. To restart dhcpd, send a SIGTERM
+ (signal 15) to the process ID contained in
_\b/_\bv_\ba_\br_\b/_\br_\bu_\bn_\b/_\bd_\bh_\bc_\bp_\bd_\b._\bp_\bi_\bd, and then re-invoke dhcpd. Because the
- DHCP server database is not as lightweight as a BOOTP
+ DHCP server database is not as lightweight as a BOOTP
database, dhcpd does not automatically restart itself when
it sees a change to the dhcpd.conf file.
C\bCO\bOM\bMM\bMA\bAN\bND\bD L\bLI\bIN\bNE\bE
- Dhcpd normally identifies all interfaces on the system
- which are up, and listens on each interface. If possi-
- ble, point-to-point interfaces and the loopback interface
- are eliminated, but on some systems this is not possible.
- For this reason, the interfaces on which dhcpd should lis-
- ten may be explicitly specified on the command line.
-
- Dhcpd normally listens on port 67, which is the BOOTP
- Server Port (the DHCP and BOOTP protocols both use this
- port). If desired, dhcpd may be invoked with the -\b-p\bp
- flag, followed by a port number, so as to provide DHCP
- service on a different port. This is mostly useful for
- debugging purposes.
-
- On some System-V systems, it may be desirable to run dhcp
- from /etc/inittab. If so, dhcpd should be invoked with
- the -\b-f\bf flag, which causes dhcpd to run in the foreground;
- otherwise, dhcpd automatically detaches itself from the
- process group that started it and runs in the background.
- This is also useful when running dhcpd under a debugger.
-
- Normally dhcpd logs its status using syslog(3). If the
- -\b-d\bd flag is specified, dhcpd will also log its status to
- its standard error descriptor. This can be useful for
- debugging, and also at sites where a complete log of all
- dhcp activity must be kept but syslogd is not reliable or
+ The names of the network interfaces on which dhcpd should
+ listen for broadcasts may be specified on the command
+ line. This should be done on systems where dhcpd is
+ unable to identify non-broadcast interfaces, but should
+ not be required on other systems. If no interface names
+ are specified on the command line dhcpd will identify all
+ network interfaces which are up, elimininating non-
+ broadcast interfaces if possible, and listen for DHCP
+ broadcasts on each interface.
+
+ If dhcpd should listen on a port other than the standard
+ (port 67), the -\b-p\bp flag may used. It should be followed by
+ the udp port number on which dhcpd should listen. This is
+ mostly useful for debugging purposes.
+
+ To run dhcpd as a foreground process, rather than allowing
+ it to run as a daemon in the background, the -\b-f\bf flag
+ should be specified. This is useful when running dhcpd
+ under a debugger, or when running it out of inittab on
+ System V systems.
+
+ To have dhcpd log to the standard error descriptor, spec-
+ ify the -\b-d\bd flag. This can be useful for debugging, and
+ also at sites where a complete log of all dhcp activity
+ must be kept but syslogd is not reliable or otherwise
dhcpd(8) dhcpd(8)
- otherwise cannot be used.
+ cannot be used. Normally, dhcpd will log all output
+ using the syslog(3) function with the log facility set to
+ LOG_DAEMON.
+
+ Dhcpd can be made to use an alternate configuration file
+ with the -\b-c\bcf\bf flag, or an alternate lease file with the -\b-l\blf\bf
+ flag. Because of the importance of using the same lease
+ database at all times when running dhcpd in production,
+ these options should be used o\bon\bnl\bly\by for testing lease files
+ or database files in a non-production environment.
C\bCO\bON\bNF\bFI\bIG\bGU\bUR\bRA\bAT\bTI\bIO\bON\bN
- The syntax of the dhcpd.conf(8) file is discussed seper-
+ The syntax of the dhcpd.conf(8) file is discussed seper-
ately. This section should be used as an overview of the
configuration process, and the dhcpd.conf(8) documentation
should be consulted for detailed reference information.
S\bSu\bub\bbn\bne\bet\bts\bs
dhcpd needs to know the subnet numbers and netmasks of all
subnets for which it will be providing service. In addi-
- tion, in order to dynamically allocate addresses, it must
+ tion, in order to dynamically allocate addresses, it must
be assigned one or more ranges of addresses on each subnet
- which it can in turn assign to client hosts as they boot.
- Thus, a very simple configuration providing DHCP support
+ which it can in turn assign to client hosts as they boot.
+ Thus, a very simple configuration providing DHCP support
might look like this:
subnet 239.252.197.0 netmask 255.255.255.0 {
range 239.252.197.113 239.252.197.250;
}
- If a subnet will only be provided with BOOTP service and
- no dynamic address assignment, the range clause can be
+ If a subnet will only be provided with BOOTP service and
+ no dynamic address assignment, the range clause can be
left out entirely, but the subnet statement must appear.
L\bLe\bea\bas\bse\be L\bLe\ben\bng\bgt\bth\bhs\bs
- DHCP leases can be assigned almost any length from zero
- seconds to infinity. What lease length makes sense for
+ DHCP leases can be assigned almost any length from zero
+ seconds to infinity. What lease length makes sense for
any given subnet, or for any given installation, will vary
depending on the kinds of hosts being served.
- For example, in an office environment where systems are
+ For example, in an office environment where systems are
added from time to time and removed from time to time, but
move relatively infrequently, it might make sense to allow
lease times of a month of more. In a final test environ-
- ment on a manufacturing floor, it may make more sense to
- assign a maximum lease length of 30 minutes - enough time
- to go through a simple test procedure on a network appli-
- ance before packaging it up for delivery.
-
- It is possible to specify two lease lengths: the default
- length that will be assigned if a client doesn't ask for
- any particular lease length, and a maximum lease length.
- These are specified as clauses to the subnet command:
-
+ ment on a manufacturing floor, it may make more sense to
dhcpd(8) dhcpd(8)
+ assign a maximum lease length of 30 minutes - enough time
+ to go through a simple test procedure on a network appli-
+ ance before packaging it up for delivery.
+
+ It is possible to specify two lease lengths: the default
+ length that will be assigned if a client doesn't ask for
+ any particular lease length, and a maximum lease length.
+ These are specified as clauses to the subnet command:
+
subnet 239.252.197.0 netmask 255.255.255.0 {
range 239.252.197.10 239.252.197.107;
default-lease-time 600;
max-lease-time 7200;
|
- This particular subnet declaration specifies a default
- lease time of 600 seconds (ten minutes), and a maximum
- lease time of 7200 seconds (two hours). Other common
- values would be 86400 (one day), 604800 (one week) and
+ This particular subnet declaration specifies a default
+ lease time of 600 seconds (ten minutes), and a maximum
+ lease time of 7200 seconds (two hours). Other common
+ values would be 86400 (one day), 604800 (one week) and
2592000 (30 days).
- Each subnet need not have the same lease--in the case of
- an office environment and a manufacturing environment
- served by the same DHCP server, it might make sense to
+ Each subnet need not have the same lease--in the case of
+ an office environment and a manufacturing environment
+ served by the same DHCP server, it might make sense to
have widely disparate values for default and maximum lease
times on each subnet.
B\bBO\bOO\bOT\bTP\bP S\bSu\bup\bpp\bpo\bor\brt\bt
- Each BOOTP client must be explicitly declared in the
- dhcpd.conf file. A very basic client declaration will
- specify the client network interface's hardware address
- and the IP address to assign to that client. If the
- client needs to be able to load a boot file from the
- server, that file's name must be specified. A simple
+ Each BOOTP client must be explicitly declared in the
+ dhcpd.conf file. A very basic client declaration will
+ specify the client network interface's hardware address
+ and the IP address to assign to that client. If the
+ client needs to be able to load a boot file from the
+ server, that file's name must be specified. A simple
bootp client declaration might look like this:
host haagen hardware ethernet 08:00:2b:4c:59:23 {
}
O\bOp\bpt\bti\bio\bon\bns\bs
- DHCP (and also BOOTP with Vendor Extensions) provide a
- mechanism whereby the server can provide the client with
- information about how to configure its network interface
- (e.g., subnet mask), and also how the client can access
- various network services (e.g., DNS, IP routers, and so
+ DHCP (and also BOOTP with Vendor Extensions) provide a
+ mechanism whereby the server can provide the client with
+ information about how to configure its network interface
+ (e.g., subnet mask), and also how the client can access
+ various network services (e.g., DNS, IP routers, and so
on).
These options can be specified on a per-subnet basis, and,
- for BOOTP clients, also on a per-client basis. In the
- event that a BOOTP client declaration specifies options
- that are also specified in its subnet declaration, the
- options specified in the client declaration take prece-
- dence. An reasonably complete DHCP configuration might
- look something like this:
-
- subnet 239.252.197.0 netmask 255.255.255.0 {
- range 239.252.197.10 239.252.197.250;
- default-lease-time 600 max-lease-time 7200;
- option subnet-mask 255.255.255.0;
- option broadcast-address 239.252.197.255;
- option routers 239.252.197.1;
+ for BOOTP clients, also on a per-client basis. In the
+ event that a BOOTP client declaration specifies options
+ that are also specified in its subnet declaration, the
+ options specified in the client declaration take
dhcpd(8) dhcpd(8)
+ precedence. An reasonably complete DHCP configuration
+ might look something like this:
+
+ subnet 239.252.197.0 netmask 255.255.255.0 {
+ range 239.252.197.10 239.252.197.250;
+ default-lease-time 600 max-lease-time 7200;
+ option subnet-mask 255.255.255.0;
+ option broadcast-address 239.252.197.255;
+ option routers 239.252.197.1;
option domain-name-servers 239.252.197.2, 239.252.197.3;
option domain-name "isc.org";
}
- A bootp host on that subnet that needs to be in a differ-
- ent domain and use a different name server might be
+ A bootp host on that subnet that needs to be in a differ-
+ ent domain and use a different name server might be
declared as follows:
host haagen hardware ethernet 08:00:2b:4c:59:23 {
option domain-name "vix.com";
}
- A more complete description of the dhcpd.conf file syntax
+ A more complete description of the dhcpd.conf file syntax
is provided in dhcpd.conf(5).
F\bFI\bIL\bLE\bES\bS
A\bAU\bUT\bTH\bHO\bOR\bR
d\bdh\bhc\bcp\bpd\bd(\b(8\b8)\b) was written by Ted Lemon <mellon@vix.com> under a
- contract with Vixie Labs. Funding for this project was
- provided by the Internet Software Corporation. Informa-
- tion about the Internet Software Consortium can be found
+ contract with Vixie Labs. Funding for this project was
+ provided by the Internet Software Corporation. Informa-
+ tion about the Internet Software Consortium can be found
at h\bht\btt\btp\bp:\b:/\b//\b/w\bww\bww\bw.\b.i\bis\bsc\bc.\b.o\bor\brg\bg/\b/i\bis\bsc\bc.\b.
-
-
-
-
-
-
-
-
-
extern struct interface_info fallback_interface;
#endif
+extern char *path_dhcpd_conf;
+extern char *path_dhcpd_db;
+extern char *path_dhcpd_pid;
+
int main PROTO ((int, char **, char **));
void cleanup PROTO ((void));
extern struct interface_info fallback_interface;
#endif
+extern char *path_dhcpd_conf;
+extern char *path_dhcpd_db;
+extern char *path_dhcpd_pid;
+
int main PROTO ((int, char **, char **));
void cleanup PROTO ((void));
#ifndef lint
static char copyright[] =
-"$Id: confpars.c,v 1.31 1996/08/30 23:39:37 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium. All rights reserved.\n";
+"$Id: confpars.c,v 1.32 1996/09/02 21:16:25 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium. All rights reserved.\n";
#endif /* not lint */
#include "dhcpd.h"
int token;
int declaration = 0;
- new_parse (_PATH_DHCPD_CONF);
+ new_parse (path_dhcpd_conf);
/* Set up the initial dhcp option universe. */
initialize_universes ();
root_group.bootp_lease_cutoff = MAX_TIME;
root_group.boot_unknown_clients = 1;
- if ((cfile = fopen (_PATH_DHCPD_CONF, "r")) == NULL)
- error ("Can't open %s: %m", _PATH_DHCPD_CONF);
+ if ((cfile = fopen (path_dhcpd_conf, "r")) == NULL)
+ error ("Can't open %s: %m", path_dhcpd_conf);
do {
token = peek_token (&val, cfile);
if (token == EOF)
char *val;
int token;
- new_parse (_PATH_DHCPD_DB);
+ new_parse (path_dhcpd_db);
/* Open the lease file. If we can't open it, fail. The reason
for this is that although on initial startup, the absence of
human has corrected the database problem, then we are left
thinking that no leases have been assigned to anybody, which
could create severe network chaos. */
- if ((cfile = fopen (_PATH_DHCPD_DB, "r")) == NULL)
+ if ((cfile = fopen (path_dhcpd_db, "r")) == NULL)
error ("Can't open lease database %s: %m -- %s",
- _PATH_DHCPD_DB,
+ path_dhcpd_db,
"check for failed database rewrite attempt!");
do {
token = next_token (&val, cfile);
#ifndef lint
static char copyright[] =
-"$Id: db.c,v 1.7 1996/08/27 09:42:26 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium. All rights reserved.\n";
+"$Id: db.c,v 1.8 1996/09/02 21:16:24 mellon Exp $ Copyright (c) 1995, 1996 The Internet Software Consortium. All rights reserved.\n";
#endif /* not lint */
#include "dhcpd.h"
/* Make a temporary lease file... */
time (&t);
- sprintf (newfname, "%s.%d", _PATH_DHCPD_DB, (int) (t & 32767));
+ sprintf (newfname, "%s.%d", path_dhcpd_db, (int) (t & 32767));
if ((db_file = fopen (newfname, "w")) == NULL) {
error ("Can't start new lease file: %m");
}
write_leases ();
/* Get the old database out of the way... */
- sprintf (backfname, "%s~", _PATH_DHCPD_DB);
+ sprintf (backfname, "%s~", path_dhcpd_db);
if (unlink (backfname) < 0 && errno != ENOENT)
error ("Can't remove old lease database backup %s: %m",
backfname);
- if (link (_PATH_DHCPD_DB, backfname) < 0)
+ if (link (path_dhcpd_db, backfname) < 0)
error ("Can't backup lease database %s to %s: %m",
- _PATH_DHCPD_DB, backfname);
+ path_dhcpd_db, backfname);
/* Move in the new file... */
- if (rename (newfname, _PATH_DHCPD_DB) < 0)
+ if (rename (newfname, path_dhcpd_db) < 0)
error ("Can't install new lease database %s to %s: %m",
- newfname, _PATH_DHCPD_DB);
+ newfname, path_dhcpd_db);
counting = 1;
}
.B -d
]
[
+.B -cf
+.I config-file
+]
+[
+.B -lf
+.I lease-file
+]
+[
.I if0
[
.I ...ifN
reliable or otherwise cannot be used. Normally, dhcpd will log all
output using the syslog(3) function with the log facility set to
LOG_DAEMON.
+.PP
+Dhcpd can be made to use an alternate configuration file with the
+.B -cf
+flag, or an alternate lease file with the
+.B -lf
+flag. Because of the importance of using the same lease database at
+all times when running dhcpd in production, these options should be
+used \fBonly\fR for testing lease files or database files in a
+non-production environment.
.SH CONFIGURATION
The syntax of the dhcpd.conf(8) file is discussed seperately. This
section should be used as an overview of the configuration process,
dhcpd - Dynamic Host Configuration Protocol Server
S\bSY\bYN\bNO\bOP\bPS\bSI\bIS\bS
- d\bdh\bhc\bcp\bpd\bd [ -\b-p\bp _\bp_\bo_\br_\bt ] [ -\b-f\bf ] [ _\bi_\bf_\b0 [ _\b._\b._\b._\bi_\bf_\bN ] ]
+ d\bdh\bhc\bcp\bpd\bd [ -\b-p\bp _\bp_\bo_\br_\bt ] [ -\b-f\bf ] [ -\b-d\bd ] [ -\b-c\bcf\bf _\bc_\bo_\bn_\bf_\bi_\bg_\b-_\bf_\bi_\bl_\be ] [ -\b-l\blf\bf
+ _\bl_\be_\ba_\bs_\be_\b-_\bf_\bi_\bl_\be ] [ _\bi_\bf_\b0 [ _\b._\b._\b._\bi_\bf_\bN ] ]
D\bDE\bES\bSC\bCR\bRI\bIP\bPT\bTI\bIO\bON\bN
The Internet Software Consortium DHCP Server, dhcpd,
- implements the Dynamic Host Configuration Protocol (DHCP)
- and the Internet Bootstrap Protocol (BOOTP). DHCP allows
- hosts on a TCP/IP network to request and be assigned IP
+ implements the Dynamic Host Configuration Protocol (DHCP)
+ and the Internet Bootstrap Protocol (BOOTP). DHCP allows
+ hosts on a TCP/IP network to request and be assigned IP
addresses, and also to discover information about the net-
- work to which they are attached. BOOTP provides similar
+ work to which they are attached. BOOTP provides similar
functionality, with certain restrictions.
O\bOP\bPE\bER\bRA\bAT\bTI\bIO\bON\bN
- The DHCP protocol allows a host which is unknown to the
- network administrator to be automatically assigned a new
- IP address out of a pool of IP addresses for its network.
+ The DHCP protocol allows a host which is unknown to the
+ network administrator to be automatically assigned a new
+ IP address out of a pool of IP addresses for its network.
In order for this to work, the network administrator allo-
- cates address pools in each subnet and enters them into
+ cates address pools in each subnet and enters them into
the dhcpd.conf(5) file.
- On startup, dhcpd reads the _\bd_\bh_\bc_\bp_\bd_\b._\bc_\bo_\bn_\bf file and stores a
- list of available addresses on each subnet in memory.
+ On startup, dhcpd reads the _\bd_\bh_\bc_\bp_\bd_\b._\bc_\bo_\bn_\bf file and stores a
+ list of available addresses on each subnet in memory.
When a client requests an address using the DHCP protocol,
dhcpd allocates an address for it. Each client is
- assigned a lease, which expires after an amount of time
+ assigned a lease, which expires after an amount of time
chosen by the administrator (by default, one day). Before
- leases expire, the clients to which leases are assigned
+ leases expire, the clients to which leases are assigned
are expected to renew them in order to continue to use the
- addresses. Once a lease has expired, the client to which
- that lease was assigned is no longer permitted to use the
+ addresses. Once a lease has expired, the client to which
+ that lease was assigned is no longer permitted to use the
leased IP address.
In order to keep track of leases across system reboots and
- server restarts, dhcpd keeps a list of leases it has
+ server restarts, dhcpd keeps a list of leases it has
assigned in the dhcpd.leases(5) file. Before dhcpd
- grants a lease to a host, it records the lease in this
- file and makes sure that the contents of the file are
- flushed to disk. This ensures that even in the event of
- a system crash, dhcpd will not forget about a lease that
- it has assigned. On startup, after reading the
- dhcpd.conf file, dhcpd reads the dhcpd.leases file to
+ grants a lease to a host, it records the lease in this
+ file and makes sure that the contents of the file are
+ flushed to disk. This ensures that even in the event of
+ a system crash, dhcpd will not forget about a lease that
+ it has assigned. On startup, after reading the
+ dhcpd.conf file, dhcpd reads the dhcpd.leases file to
refresh its memory about what leases have been assigned.
- New leases are appended to the end of the dhcpd.leases
- file. In order to prevent the file from becoming arbi-
- trarily large, from time to time dhcpd creates a new
- dhcpd.leases file from its in-core lease database. Once
- this file has been written to disk, the old file is
- renamed _\bd_\bh_\bc_\bp_\bd_\b._\bl_\be_\ba_\bs_\be_\bs_\b~, and the new file is renamed
- dhcpd.leases. If the system crashes in the middle of
- this process, whichever dhcpd.leases file remains will
+ New leases are appended to the end of the dhcpd.leases
+ file. In order to prevent the file from becoming arbi-
+ trarily large, from time to time dhcpd creates a new
+ dhcpd.leases file from its in-core lease database. Once
+ this file has been written to disk, the old file is
+ renamed _\bd_\bh_\bc_\bp_\bd_\b._\bl_\be_\ba_\bs_\be_\bs_\b~, and the new file is renamed
+ dhcpd.leases. If the system crashes in the middle of
dhcpd(8) dhcpd(8)
+ this process, whichever dhcpd.leases file remains will
contain all the lease information, so there is no need for
a special crash recovery process.
- BOOTP support is also provided by this server. Unlike
- DHCP, the BOOTP protocol does not provide a protocol for
+ BOOTP support is also provided by this server. Unlike
+ DHCP, the BOOTP protocol does not provide a protocol for
recovering dynamically-assigned addresses once they are no
- longer needed. It is still possible to dynamically
+ longer needed. It is still possible to dynamically
assign addresses to BOOTP clients, but some administrative
- process for reclaiming addresses is required. By
- default, leases are granted to BOOTP clients in perpetu-
+ process for reclaiming addresses is required. By
+ default, leases are granted to BOOTP clients in perpetu-
ity, although the network administrator may set an earlier
- cutoff date or a shorter lease length for BOOTP leases if
+ cutoff date or a shorter lease length for BOOTP leases if
that makes sense.
- BOOTP clients may also be served in the old standard way,
+ BOOTP clients may also be served in the old standard way,
which is to simply provide a declaration in the dhcpd.conf
- file for each BOOTP client, permanently assigning an
+ file for each BOOTP client, permanently assigning an
address to each client.
- Whenever changes are made to the dhcpd.conf file, dhcpd
- must be restarted. To restart dhcpd, send a SIGTERM
- (signal 15) to the process ID contained in
+ Whenever changes are made to the dhcpd.conf file, dhcpd
+ must be restarted. To restart dhcpd, send a SIGTERM
+ (signal 15) to the process ID contained in
_\b/_\bv_\ba_\br_\b/_\br_\bu_\bn_\b/_\bd_\bh_\bc_\bp_\bd_\b._\bp_\bi_\bd, and then re-invoke dhcpd. Because the
- DHCP server database is not as lightweight as a BOOTP
+ DHCP server database is not as lightweight as a BOOTP
database, dhcpd does not automatically restart itself when
it sees a change to the dhcpd.conf file.
C\bCO\bOM\bMM\bMA\bAN\bND\bD L\bLI\bIN\bNE\bE
- Dhcpd normally identifies all interfaces on the system
- which are up, and listens on each interface. If possi-
- ble, point-to-point interfaces and the loopback interface
- are eliminated, but on some systems this is not possible.
- For this reason, the interfaces on which dhcpd should lis-
- ten may be explicitly specified on the command line.
-
- Dhcpd normally listens on port 67, which is the BOOTP
- Server Port (the DHCP and BOOTP protocols both use this
- port). If desired, dhcpd may be invoked with the -\b-p\bp
- flag, followed by a port number, so as to provide DHCP
- service on a different port. This is mostly useful for
- debugging purposes.
-
- On some System-V systems, it may be desirable to run dhcp
- from /etc/inittab. If so, dhcpd should be invoked with
- the -\b-f\bf flag, which causes dhcpd to run in the foreground;
- otherwise, dhcpd automatically detaches itself from the
- process group that started it and runs in the background.
- This is also useful when running dhcpd under a debugger.
-
- Normally dhcpd logs its status using syslog(3). If the
- -\b-d\bd flag is specified, dhcpd will also log its status to
- its standard error descriptor. This can be useful for
- debugging, and also at sites where a complete log of all
- dhcp activity must be kept but syslogd is not reliable or
+ The names of the network interfaces on which dhcpd should
+ listen for broadcasts may be specified on the command
+ line. This should be done on systems where dhcpd is
+ unable to identify non-broadcast interfaces, but should
+ not be required on other systems. If no interface names
+ are specified on the command line dhcpd will identify all
+ network interfaces which are up, elimininating non-
+ broadcast interfaces if possible, and listen for DHCP
+ broadcasts on each interface.
+
+ If dhcpd should listen on a port other than the standard
+ (port 67), the -\b-p\bp flag may used. It should be followed by
+ the udp port number on which dhcpd should listen. This is
+ mostly useful for debugging purposes.
+
+ To run dhcpd as a foreground process, rather than allowing
+ it to run as a daemon in the background, the -\b-f\bf flag
+ should be specified. This is useful when running dhcpd
+ under a debugger, or when running it out of inittab on
+ System V systems.
+
+ To have dhcpd log to the standard error descriptor, spec-
+ ify the -\b-d\bd flag. This can be useful for debugging, and
+ also at sites where a complete log of all dhcp activity
+ must be kept but syslogd is not reliable or otherwise
dhcpd(8) dhcpd(8)
- otherwise cannot be used.
+ cannot be used. Normally, dhcpd will log all output
+ using the syslog(3) function with the log facility set to
+ LOG_DAEMON.
+
+ Dhcpd can be made to use an alternate configuration file
+ with the -\b-c\bcf\bf flag, or an alternate lease file with the -\b-l\blf\bf
+ flag. Because of the importance of using the same lease
+ database at all times when running dhcpd in production,
+ these options should be used o\bon\bnl\bly\by for testing lease files
+ or database files in a non-production environment.
C\bCO\bON\bNF\bFI\bIG\bGU\bUR\bRA\bAT\bTI\bIO\bON\bN
- The syntax of the dhcpd.conf(8) file is discussed seper-
+ The syntax of the dhcpd.conf(8) file is discussed seper-
ately. This section should be used as an overview of the
configuration process, and the dhcpd.conf(8) documentation
should be consulted for detailed reference information.
S\bSu\bub\bbn\bne\bet\bts\bs
dhcpd needs to know the subnet numbers and netmasks of all
subnets for which it will be providing service. In addi-
- tion, in order to dynamically allocate addresses, it must
+ tion, in order to dynamically allocate addresses, it must
be assigned one or more ranges of addresses on each subnet
- which it can in turn assign to client hosts as they boot.
- Thus, a very simple configuration providing DHCP support
+ which it can in turn assign to client hosts as they boot.
+ Thus, a very simple configuration providing DHCP support
might look like this:
subnet 239.252.197.0 netmask 255.255.255.0 {
range 239.252.197.113 239.252.197.250;
}
- If a subnet will only be provided with BOOTP service and
- no dynamic address assignment, the range clause can be
+ If a subnet will only be provided with BOOTP service and
+ no dynamic address assignment, the range clause can be
left out entirely, but the subnet statement must appear.
L\bLe\bea\bas\bse\be L\bLe\ben\bng\bgt\bth\bhs\bs
- DHCP leases can be assigned almost any length from zero
- seconds to infinity. What lease length makes sense for
+ DHCP leases can be assigned almost any length from zero
+ seconds to infinity. What lease length makes sense for
any given subnet, or for any given installation, will vary
depending on the kinds of hosts being served.
- For example, in an office environment where systems are
+ For example, in an office environment where systems are
added from time to time and removed from time to time, but
move relatively infrequently, it might make sense to allow
lease times of a month of more. In a final test environ-
- ment on a manufacturing floor, it may make more sense to
- assign a maximum lease length of 30 minutes - enough time
- to go through a simple test procedure on a network appli-
- ance before packaging it up for delivery.
-
- It is possible to specify two lease lengths: the default
- length that will be assigned if a client doesn't ask for
- any particular lease length, and a maximum lease length.
- These are specified as clauses to the subnet command:
-
+ ment on a manufacturing floor, it may make more sense to
dhcpd(8) dhcpd(8)
+ assign a maximum lease length of 30 minutes - enough time
+ to go through a simple test procedure on a network appli-
+ ance before packaging it up for delivery.
+
+ It is possible to specify two lease lengths: the default
+ length that will be assigned if a client doesn't ask for
+ any particular lease length, and a maximum lease length.
+ These are specified as clauses to the subnet command:
+
subnet 239.252.197.0 netmask 255.255.255.0 {
range 239.252.197.10 239.252.197.107;
default-lease-time 600;
max-lease-time 7200;
|
- This particular subnet declaration specifies a default
- lease time of 600 seconds (ten minutes), and a maximum
- lease time of 7200 seconds (two hours). Other common
- values would be 86400 (one day), 604800 (one week) and
+ This particular subnet declaration specifies a default
+ lease time of 600 seconds (ten minutes), and a maximum
+ lease time of 7200 seconds (two hours). Other common
+ values would be 86400 (one day), 604800 (one week) and
2592000 (30 days).
- Each subnet need not have the same lease--in the case of
- an office environment and a manufacturing environment
- served by the same DHCP server, it might make sense to
+ Each subnet need not have the same lease--in the case of
+ an office environment and a manufacturing environment
+ served by the same DHCP server, it might make sense to
have widely disparate values for default and maximum lease
times on each subnet.
B\bBO\bOO\bOT\bTP\bP S\bSu\bup\bpp\bpo\bor\brt\bt
- Each BOOTP client must be explicitly declared in the
- dhcpd.conf file. A very basic client declaration will
- specify the client network interface's hardware address
- and the IP address to assign to that client. If the
- client needs to be able to load a boot file from the
- server, that file's name must be specified. A simple
+ Each BOOTP client must be explicitly declared in the
+ dhcpd.conf file. A very basic client declaration will
+ specify the client network interface's hardware address
+ and the IP address to assign to that client. If the
+ client needs to be able to load a boot file from the
+ server, that file's name must be specified. A simple
bootp client declaration might look like this:
host haagen hardware ethernet 08:00:2b:4c:59:23 {
}
O\bOp\bpt\bti\bio\bon\bns\bs
- DHCP (and also BOOTP with Vendor Extensions) provide a
- mechanism whereby the server can provide the client with
- information about how to configure its network interface
- (e.g., subnet mask), and also how the client can access
- various network services (e.g., DNS, IP routers, and so
+ DHCP (and also BOOTP with Vendor Extensions) provide a
+ mechanism whereby the server can provide the client with
+ information about how to configure its network interface
+ (e.g., subnet mask), and also how the client can access
+ various network services (e.g., DNS, IP routers, and so
on).
These options can be specified on a per-subnet basis, and,
- for BOOTP clients, also on a per-client basis. In the
- event that a BOOTP client declaration specifies options
- that are also specified in its subnet declaration, the
- options specified in the client declaration take prece-
- dence. An reasonably complete DHCP configuration might
- look something like this:
-
- subnet 239.252.197.0 netmask 255.255.255.0 {
- range 239.252.197.10 239.252.197.250;
- default-lease-time 600 max-lease-time 7200;
- option subnet-mask 255.255.255.0;
- option broadcast-address 239.252.197.255;
- option routers 239.252.197.1;
+ for BOOTP clients, also on a per-client basis. In the
+ event that a BOOTP client declaration specifies options
+ that are also specified in its subnet declaration, the
+ options specified in the client declaration take
dhcpd(8) dhcpd(8)
+ precedence. An reasonably complete DHCP configuration
+ might look something like this:
+
+ subnet 239.252.197.0 netmask 255.255.255.0 {
+ range 239.252.197.10 239.252.197.250;
+ default-lease-time 600 max-lease-time 7200;
+ option subnet-mask 255.255.255.0;
+ option broadcast-address 239.252.197.255;
+ option routers 239.252.197.1;
option domain-name-servers 239.252.197.2, 239.252.197.3;
option domain-name "isc.org";
}
- A bootp host on that subnet that needs to be in a differ-
- ent domain and use a different name server might be
+ A bootp host on that subnet that needs to be in a differ-
+ ent domain and use a different name server might be
declared as follows:
host haagen hardware ethernet 08:00:2b:4c:59:23 {
option domain-name "vix.com";
}
- A more complete description of the dhcpd.conf file syntax
+ A more complete description of the dhcpd.conf file syntax
is provided in dhcpd.conf(5).
F\bFI\bIL\bLE\bES\bS
A\bAU\bUT\bTH\bHO\bOR\bR
d\bdh\bhc\bcp\bpd\bd(\b(8\b8)\b) was written by Ted Lemon <mellon@vix.com> under a
- contract with Vixie Labs. Funding for this project was
- provided by the Internet Software Corporation. Informa-
- tion about the Internet Software Consortium can be found
+ contract with Vixie Labs. Funding for this project was
+ provided by the Internet Software Corporation. Informa-
+ tion about the Internet Software Consortium can be found
at h\bht\btt\btp\bp:\b:/\b//\b/w\bww\bww\bw.\b.i\bis\bsc\bc.\b.o\bor\brg\bg/\b/i\bis\bsc\bc.\b.
-
-
-
-
-
-
-
-
-
projects / thirdparty / dhcp.git / commitdiff
