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-dhclient(8) dhclient(8)
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- dhcpd - Dynamic Host Configuration Protocol Client
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- d\bdh\bhc\bcl\bli\bie\ben\bnt\bt [ -\b-p\bp _\bp_\bo_\br_\bt ] [ -\b-d\bd ] [ _\bi_\bf_\b0 [ _\b._\b._\b._\bi_\bf_\bN ] ]
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- The Internet Software Consortium DHCP Client, dhclient,
- provides a means for configuring one or more network
- interfaces using the Dynamic Host Configuration Protocol,
- BOOTP protocol, or if these protocols fail, by statically
- assigning an address.
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- The DHCP protocol allows a host to contact a central
- server which maintains a list of IP addresses which may be
- assigned on one or more subnets. A DHCP client may
- request an address from this pool, and then use it on a
- temporary basis for communication on network. The DHCP
- protocol also provides a mechanism whereby a client can
- learn important details about the network to which it is
- attached, such as the location of a default router, the
- location of a name server, and so on.
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- On startup, dhclient reads the _\bd_\bh_\bc_\bl_\bi_\be_\bn_\bt_\b._\bc_\bo_\bn_\bf for configu-
- ration instructions. It then gets a list of all the net-
- work interfaces that are configured in the current system.
- For each interface, it attempts to configure the interface
- using the DHCP protocol.
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- In order to keep track of leases across system reboots and
- server restarts, dhclient keeps a list of leases it has
- been assigned in the dhclient.leases(5) file. On
- startup, after reading the dhclient.conf file, dhclient
- reads the dhclient.leases file to refresh its memory about
- what leases it has been assigned.
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- When a new lease is acquired, it is appended to the end of
- the dhclient.leases file. In order to prevent the file
- from becoming arbitrarily large, from time to time
- dhclient creates a new dhclient.leases file from its in-
- core lease database. The old version of the
- dhclient.leases file is retained under the name
- _\bd_\bh_\bc_\bp_\bd_\b._\bl_\be_\ba_\bs_\be_\bs_\b~ until the next time dhclient rewrites the
- database.
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- Old leases are kept around in case the DHCP server is
- unavailable when dhclient is first invoked (generally dur-
- ing the initial system boot process). In that event, old
- leases from the dhclient.leases file which have not yet
- expired are tested, and if they are determined to be
- valid, they are used until either they expire or the DHCP
- server becomes available.
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-dhclient(8) dhclient(8)
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- A mobile host which may sometimes need to access a network
- on which no DHCP server exists may be preloaded with a
- lease for a fixed address on that network. When all
- attempts to contact a DHCP server have failed, dhclient
- will try to validate the static lease, and if it succeeds,
- will use that lease until it is restarted.
-
- A mobile host may also travel to some networks on which
- DHCP is not available but BOOTP is. In that case, it may
- be advantageous to arrange with the network administrator
- for an entry on the BOOTP database, so that the host can
- boot quickly on that network rather than cycling through
- the list of old leases.
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- The names of the network interfaces that dhclient should
- attempt to configure may be specified on the command line.
- If no interface names are specified on the command line
- dhclient will identify all network interfaces, elimininat-
- ing non-broadcast interfaces if possible, and attempt to
- configure each interface.
-
- If dhclient should listen and transmit on a port other
- than the standard (port 68), the -\b-p\bp flag may used. It
- should be followed by the udp port number that dhclient
- should use. This is mostly useful for debugging purposes.
-
- Dhclient will normally run in the foreground until it has
- configured an interface, and then will revert to running
- in the background. To run force dhclient to always run as
- a foreground process, the -\b-d\bd flag should be specified.
- This is useful when running dhclient under a debugger, or
- when running it out of inittab on System V systems.
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- The syntax of the dhclient.conf(8) file is discussed
- seperately.
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- /\b/e\bet\btc\bc/\b/d\bdh\bhc\bcl\bli\bie\ben\bnt\bt.\b.c\bco\bon\bnf\bf,\b, /\b/v\bva\bar\br/\b/d\bdb\bb/\b/d\bdh\bhc\bcl\bli\bie\ben\bnt\bt.\b.l\ble\bea\bas\bse\bes\bs,\b,
- /\b/v\bva\bar\br/\b/r\bru\bun\bn/\b/d\bdh\bhc\bcl\bli\bie\ben\bnt\bt.\b.p\bpi\bid\bd,\b, /\b/v\bva\bar\br/\b/d\bdb\bb/\b/d\bdh\bhc\bcl\bli\bie\ben\bnt\bt.\b.l\ble\bea\bas\bse\bes\bs~\b~.\b.
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- dhcpd(8), dhcrelay(8), dhclient.conf(5),
- dhclient.leases(5)
-
-A\bAU\bUT\bTH\bHO\bOR\bR
- d\bdh\bhc\bcl\bli\bie\ben\bnt\bt(\b(8\b8)\b) has been written for the Internet Software
- Consortium by Ted Lemon <mellon@fugue.com> in cooperation
- with Vixie Enterprises. To learn more about the Internet
- Software Consortium, see h\bht\btt\btp\bp:\b:/\b//\b/w\bww\bww\bw.\b.v\bvi\bix\bx.\b.c\bco\bom\bm/\b/i\bis\bsc\bc.\b. To learn
- more about Vixie Enterprises, see h\bht\btt\btp\bp:\b:/\b//\b/w\bww\bww\bw.\b.v\bvi\bix\bx.\b.c\bco\bom\bm.\b.
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-dhclient(8) dhclient(8)
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- This client was substantially modified and enhanced by
- Elliot Poger for use on Linux while he was working on the
- MosquitoNet project at Stanford.
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- The current version owes much to Elliot's Linux enhance-
- ments, but was substantially reorganized and partially
- rewritten by Ted Lemon so as to use the same networking
- framework that the Internet Software Consortium DHCP
- server uses. Much system-specific configuration code was
- moved into a shell script so that as support for more
- operating systems is added, it will not be necessary to
- port and maintain system-specific configuration code to
- these operating systems - instead, the shell script can
- invoke the native tools to accomplish the same purpose.
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projects / thirdparty / dhcp.git / commitdiff
