.\" $OpenBSD: dhclient.conf.5,v 1.52 2022/03/31 17:27:19 naddy Exp $ .\" .\" Copyright (c) 1997 The Internet Software Consortium. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of The Internet Software Consortium nor the names .\" of its contributors may be used to endorse or promote products derived .\" from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE INTERNET SOFTWARE CONSORTIUM AND .\" CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, .\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE .\" DISCLAIMED. IN NO EVENT SHALL THE INTERNET SOFTWARE CONSORTIUM OR .\" CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT .\" LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF .\" USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND .\" ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, .\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT .\" OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" This software has been written for the Internet Software Consortium .\" by Ted Lemon in cooperation with Vixie .\" Enterprises. To learn more about the Internet Software Consortium, .\" see ``http://www.isc.org/isc''. To learn more about Vixie .\" Enterprises, see ``http://www.vix.com''. .\" .Dd $Mdocdate: July 17 2020 $ .Dt DHCLIENT.CONF 5 .Os .Sh NAME .Nm dhclient.conf .Nd DHCP client configuration file .Sh DESCRIPTION .Nm is the configuration file for .Xr dhclient 8 . It is a free-form ASCII text file made up of declarations, extra tabs and newlines for formatting purposes and comments. Keywords in the file are case-insensitive. Comments begin with the .Sq # character and extend to the end of the current line. .Sh PROTOCOL TIMING DECLARATIONS .Bl -tag -width Ds .It Ic backoff-cutoff Ar seconds ; Sets the maximum number of seconds to wait before retransmitting a packet. The default is 10 seconds. .It Ic initial-interval Ar seconds ; Sets the number of seconds between the first packet transmission and the first retransmission of the packet. The default is 1 second. .It Ic link-timeout Ar seconds ; Sets the number of seconds to wait for a lease before going into the background as a daemon. The default is 10 seconds. .It Ic reboot Ar seconds ; Sets the number of seconds to wait before giving up on reacquiring the previous lease, and how long to attempt unicast renewal requests before falling back to broadcast renewal requests. The default is 1 second. .It Ic retry Ar seconds ; Sets the number of seconds to wait before starting a new attempt to obtain a lease. The default is 1 second. .It Ic select-timeout Ar seconds ; Sets the number of seconds to wait for additional leases after the first lease arrives. After .Ic select-timeout seconds the best lease received will be selected. The default is 0 seconds, i.e. immediately use the first acceptable lease received. .It Ic timeout Ar seconds ; Sets the number of seconds to wait for a lease. If no lease is received, the first valid lease in .Xr dhclient.leases 5 will be used. The default is 30 seconds. .El .Sh DHCP OPTION DECLARATIONS .Bl -tag -width Ds .It Ic append Ar option option-value ; Append .Ar option-value to the value of .Ar option in the lease. Each .Ic append for .Ar option overrides any previous .Ic append , .Ic default , .Ic ignore , .Ic prepend or .Ic supersede for .Ar option . .Pp If the option's data cannot be appended to, i.e. it has a fixed size, then .Ic append will be treated as .Ic default . .It Ic default Ar option option-value ; If no value for .Ar option is present in the lease, use .Ar option-value . Each .Ic default for .Ar option overrides any previous .Ic append , .Ic default , .Ic ignore , .Ic prepend or .Ic supersede for .Ar option . .It Ic ignore Op Ar option , ... ; Discard values provided for the listed options. .Ic ignore statements are cumulative, except that an empty list will remove all previously specified options. Each .Ic ignore for .Ar option overrides any previous .Ic append , .Ic default , .Ic prepend or .Ic supersede for .Ar option . .It Ic prepend Ar option option-value ; Prepend .Ar option-value to the value of .Ar option in the lease. Each .Ic prepend for .Ar option overrides any previous .Ic append , .Ic default , .Ic ignore , .Ic prepend or .Ic supersede for .Ar option . .Pp If the option's data cannot be prepended to, i.e. it has a fixed size, then .Ic prepend will be treated as .Ic supersede . .It Ic request Op Ar option , ... ; Ask that any lease contain values for the listed options. .Ic request statements are cumulative, except that an empty list will remove all previously specified options. The default is to request the options bootfile-name, broadcast-address, classless-static-routes, host-name, domain-name, domain-name-servers, domain-search, routers, subnet-mask, tftp-server-name and time-offset. .It Ic require Op Ar option , ... ; Discard leases that do not contain the listed options. .Ic require statements are cumulative, except that an empty list will remove all previously specified options. The default is to require the option subnet-mask. .It Ic send Ar option option-value ; Include .Ar option-value in requests for a lease. To include multiple options in requests, .Ic send can be used multiple times. .It Ic supersede Ar option option-value ; Use .Ar option-value for the given .Ar option regardless of the value in the lease. Each .Ic supersede for .Ar option overrides any previous .Ic append , .Ic default , .Ic ignore , .Ic prepend or .Ic supersede for .Ar option . .It Ic uselease Op Ar option , ... ; Use the unmodified values provided in the lease for any specified .Ar option . .Ic uselease statements are cumulative. If no .Ar option is specified, all lease option values will be used unmodified. .Ic uselease for .Ar option overrides any previous .Ic append , .Ic default , .Ic ignore , .Ic prepend or .Ic supersede for .Ar option . .El .Sh OTHER DECLARATIONS .Bl -tag -width Ds .It Ic filename Ar path ; Use .Ar path instead of the .Ic file field of the DHCP offer when binding a lease. .It Ic fixed-address Ar ip-address ; Use .Ar ip-address instead of the .Ic yiaddr field of the DHCP offer when binding a lease. .It Ic interface Qo Ar name Qc No { Ar declaration ; ... ; No } Apply any .Ar declaration only to the named interface. .It Ic reject Ar ip-address ; Discard leases from the specified address. If more than one .Ic reject is present, all leases from any of the addresses will be discarded. .It Ic next-server Ar ip-address ; Use .Ar ip-address instead of the .Ic siaddr field of the DHCP offer when binding a lease. .It Ic server-name Ar host ; Use .Ar host instead of the .Ic sname field of the DHCP offer when binding a lease. .El .Sh FILES .Bl -tag -width /etc/examples/dhclient.conf -compact .It Pa /etc/dhclient.conf .It Pa /etc/examples/dhclient.conf .El .Sh SEE ALSO .Xr dhclient.leases 5 , .Xr dhcp-options 5 , .Xr dhcpd.conf 5 , .Xr dhclient 8 , .Xr dhcpd 8