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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