MAN page from openSUSE Tumbleweed wicked-0.6.45-1.1.i586.rpm

IFCFG-DHCP

Section: Network configuration (5)
Updated: September 2014
Index

NAME

ifcfg-dhcp - common DHCPv4 and DHCPv6 elements of network interface configuration

SYNOPSIS

/etc/sysconfig/network/dhcp
/etc/sysconfig/network/ifcfg-*

VARIABLES

The following is a list of DHCPv4 and DHCPv6 related variables that are globallyconfigured in /etc/sysconfig/network/dhcp. When appropriate, examples aregiven in parentheses, and default values will either be explicity mentioned, orwill be marked by a "*". Please note, that to override any of the variables fora specific interface, simply redefine the variable in the appropriate ifcfg-file.

DHVPv4 Specific Variables

DHCLIENT_SET_HOSTNAME {no*|yes}

Should the DHCPv4 client set the hostname?When it is likely that this would occur during a running X session,your DISPLAY variable could be screwed up and you won't be able to opennew windows anymore, then this should be "no".If it happens during booting it won't be a problem and you cansafely say "yes" here. For a roaming notebook with X kept running, "no"makes more sense.

DHCLIENT_HOSTNAME_OPTION {AUTO*|<a host name>| }

Specifies the hostname option field when DHCPv4 client sends messages.Some DHCP servers will update nameserver entries (dynamic DNS) to it.Also, some DHCP servers, notably those used by @Home Networks, requirethe hostname option field containing a specific string in the DHCPmessages from clients.When set to "AUTO", the current hostname from /etc/hostname is sent.Use this variable to override it with another hostname, or leave itempty to not send any hostname.

DHCLIENT_FQDN_ENABLED {enabled|disabled|default*| }

Default is to use the FQDN option, when the DHCLIENT_HOSTNAME_OPTIONvariable is set to a full hostname, that is, when it contains a dot.When DHCLIENT_HOSTNAME_OPTION is set to AUTO, short hostname from/etc/hostname is send via hostname option 12 (same as SLES-11).

DHCLIENT_FQDN_UPDATE {both|ptr|none| }

Request to update A and PTR or only the PTR DNS records using thehostname specified in the DHCLIENT_HOSTNAME_OPTION variable.Default is to update both when hostname is given or nonewhen hostname is empty and DHCLIENT_FQDN_ENABLED is set to enabled.

DHCLIENT_FQDN_QUALIFY {yes*|no}

Qualify relative sub-domains/hostname in the DHCLIENT_HOSTNAME_OPTIONvariable adding a final dot ('foo.bar' -> 'foo.bar.').When disabled, the DHCP server may append it's update domain the host-name (e.g. 'foo.bar' -> 'foo.bar.example.net').

DHCLIENT_FQDN_ENCODE {yes*|no}

The FQDN option is encoding hostnames using canonical DNS wire formatby default. This flag permits to enable use of the deprecated asciiformat limited to a single label (short hostname) for compatibilitypurposes with draft implementation, which may be unsupported andcause that a DHCP server ignores the fqdn option requests completely.

DHCLIENT_SET_DEFAULT_ROUTE {yes*|no}

Should the DHCP client set a default route (default Gateway)?When multiple copies of DHCP clients run, it would make sense that onlyone of them does it.

DHCLIENT_ROUTE_PRIORITY

This option allows to set a metric/priority for DHCPv4 routes. Default is 0.

DHCLIENT_CLIENT_ID

Specifies a client identifier string. By default an id derived from thehardware address of the network interface is sent as client identifier.

DHCLIENT_USER_CLASS_FORMAT {string*|rfc3004}

Specifies the format of the DHCLIENT_USER_CLASS_ID variable.The DHCPv4 option and it's format is specified by RFC3004 as an arrayof class identifiers, but most DHCP clients/servers aren't compliantwith the specification and send/expect a single string without properRFC3004 length-value tuple format instead.When set to "rfc3004" DHCLIENT_USER_CLASS_ID[SUFFIX] permit an RFCcompliant array, otherwise DHCLIENT_USER_CLASS_ID is used as string.

DHCLIENT_USER_CLASS_ID[SUFFIX]

Specifies the user class identifier [array] to send in dhcp requests.The DHCLIENT_USER_CLASS_FORMAT variable specified how to interpret it.

DHCLIENT_REQUEST_OPTION[SUFFIX]

Specifies a space separate list of additional DHCPv4 options to request.The options can be specified by their code number or by name when definedas custom dhcp option (see wicked-config.5 man page).

DHCLIENT_LEASE_TIME

Specifies the lease time (in seconds), that is suggested to the server. Defaultis unset which means to use the lease time offered by the server.

DHCLIENT_USE_LAST_LEASE {yes*|no}

This setting controls whether the DHCP client should try to use DHCP settingsprovided in its last lease when the DHCP-server is not reachable andthe lease hasn't expired yet.Set this variable to "no" to disable the fallback to the last lease.

DHCLIENT_RELEASE_BEFORE_QUIT {yes|no*}

Send a DHCPRELEASE to the server (sign off the address)?This may lead to getting a different address/hostname next time an addressis requested. But some servers require it.

DHCLIENT_SLEEP

Some interfaces need time to initialize and/or do not report correct status.Add the latency time in seconds so these can be handled properly. Shouldprobably set per interface rather than here.This setting causes a sleep time before DHCP clients are started regardlessof the link status.Note: RFC 2131 specifies, that the DHCP client should wait a random timebetween one and ten seconds to desynchronize the use of DHCP at startup.We do not use this initial delay to not slow down start/boot time. By default,this is set to 0.

DHCLIENT_WAIT_AT_BOOT

The DHCP client will try to get a lease for DHCLIENT_WAIT_AT_BOOT seconds,then inform the waiting ifup, that it continues in background.When you increase this time, increase also the WAIT_FOR_INTERFACES variablee.g. to a value twice as high as the time specified here.Default is 15 seconds.

DHCLIENT_TIMEOUT

The DHCP client will stop processing / fail after this time when it doesnot get a reply from the DHCP server. Before you set this variable, take alook at DHCLIENT_WAIT_AT_BOOT allowing to continue in background instead.Default value is 0.

DHCLIENT_UPDATE {default,none,all,dns,ntp,nis,tz,boot,smb,nds,slp,sip,log}

This variable permits to specify a space separated list of build-infacility names supported by the dhcp4 client modifying the defaultoptions used in requests and to update system settings (via netconfig).

When empty, default settings configured in wicked-config(5) or built-indefaults are used. The special "default", "all", and "none" sets enableto request none, the built-in default set or all supported options,respectively. A "no-" or "-" in the front of a facility name permit toremove/disable it from the currently applied set, e.g. "default,-nis"disables request for nis options.More specific variables as DHCLIENT_SET_DEFAULT_ROUTE,DHCLIENT_SET_HOSTNAMEor the MTU option have higher precedence.

DHCPv6 Specific Variables

DHCLIENT6_MODE {auto*|info|managed}

This option allows to specify the request mode used by the DHCPv6client when the BOOTPROTO is set to dhcp or dhcp6, and overridesthe "Managed Address Configuration" and the "Other Configuration"flags provided by the IPv6 router its Router Advertisement (RA)for the network connected to this interface.

auto: Follow RA flags, remain silent when no RA flag is set.
info: Request other configuration (dns,ntp) only, no IP address.
managed: Request IP address as well as other configuration.

DHCLIENT6_RAPID_COMMIT {yes*|no}

This option allows the DHCPv6 client to indicate its desire to acceptrapid commit leases using two-packet exchange (solicitation, lease ack)instead of the four packet (solicitation, offer, request, lease ack).

DHCLIENT6_SET_HOSTNAME {yes|no*}

Should the DHCPv6 client set the hostname?When it is likely that this would occur during a running X session,your DISPLAY variable could be screwed up and you won't be able toopen new windows anymore, then this should be "no".If it happens during booting it won't be a problem and you cansafely say "yes" here. For a roaming notebook with X kept running,"no" makes more sense.

DHCLIENT6_HOSTNAME_OPTION {AUTO*|<a host name>| }

Specifies the hostname option field when DHCPv6 client sends messages.Some DHCP servers will update nameserver entries (dynamic DNS) to it.When set to "AUTO", the current hostname from /etc/hostname is sent.Use this variable to override it with another hostname, or leave itempty to not send any hostname.

DHCLIENT6_FQDN_ENABLED {enabled|disabled|default*| }

Default is to use the FQDN option, when the DHCLIENT6_HOSTNAME_OPTIONvariable provides a hostname.When DHCLIENT6_HOSTNAME_OPTION is set to AUTO, short hostname from the/etc/hostname file is send (same to SLES-11).

DHCLIENT6_FQDN_UPDATE {both|ptr|none| }

Request to update AAAA and PTR or only the PTR DNS records using thehostname specified in DHCLIENT6_HOSTNAME_OPTION variable.Default is to update both when hostname is set or nonewhen hostname is empty and DHCLIENT6_FQDN_ENABLED is set to enabled.

DHCLIENT6_FQDN_QUALIFY {yes*|no}

Qualify relative sub-domains/hostname in the DHCLIENT6_HOSTNAME_OPTIONvariable adding a final dot ('foo.bar' -> 'foo.bar.').When disabled, the DHCP server may append it's update domain the host-name (e.g. 'foo.bar' -> 'foo.bar.example.net').

DHCLIENT6_REQUEST_OPTION[SUFFIX]

Specifies a space separate list of additional DHCPv6 options to request.The options can be specified by their code number or by name when definedas custom dhcp option (see wicked-config.5 man page).

DHCLIENT6_LEASE_TIME

Specifies the preferred lifetime (in seconds) used as T1/renewal
(1/2 of it) and T1/rebind (4/5 of it) in DHCPv6 IA NA requests.
Default is to not propose anything but use the times as offered
by the DHCPv6 server.

DHCLIENT6_USE_LAST_LEASE {yes*|no}

This setting controls whether DHCPv6 client should try to use settingsprovided in its last lease when the DHCPv6-server is not reachable andthe lease hasn't expired yet.Set this variable to "no" to disable the fallback to the last lease.

DHCLIENT6_RELEASE_BEFORE_QUIT {yes|no*}

Send a DHCPv6 RELEASE to the server (sign off the address)?This may lead to getting a different address/hostname next time an addressis requested. But some servers require it.

DHCLIENT6_SLEEP

Some interfaces need time to initialize and/or do not report correct status.By default, DHCPv6 waits until the link-local address (fe80::) is availableand then ~1 second as specified by RFC3315.This setting allows override to use a non-standsrd initial delay. Defaultis 0.

DHCLIENT6_WAIT_AT_BOOT

The DHCPv6 client will try to get a lease for DHCLIENT6_WAIT_AT_BOOT seconds,then inform the waiting ifup, that it continues in background.When you increase this time, increase also the WAIT_FOR_INTERFACES variablee.g. to a value twice as high as the time specified here.Default is 15 seconds.

DHCLIENT6_TIMEOUT

The DHCPv6 client will stop processing / fail after this time when it doesnot get a reply from the DHCPv6 server. Before you set this variable, take alook at DHCLIENT6_WAIT_AT_BOOT allowing to continue in background instead.

DHCLIENT6_UPDATE {default,none,all,dns,ntp,tz,boot,nis,sip}

This variable permits to specify a space separated list of build-infacility names supported by the dhcp6 client modifying the defaultoptions used in requests and to update system settings (via netconfig).

When empty, default settings configured in wicked-config(5) or built-indefaults are used. The special "default", "all", and "none" sets enableto request none, the built-in default set or all supported options,respectively. A "no-" or "-" in the front of a facility name permit toremove/disable it from the currently applied set, e.g. "default,-nis"disables request for nis options.The more specific variable DHCLIENT6_SET_HOSTNAME has higher precedence.

COPYRIGHT

BUGS

Please report bugs at <https://bugzilla.novell.com/index.cgi>

AUTHOR

Marius Tomaschewski -- wicked

This document was created byman2html,using the manual pages.