x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
IFCFG-DHCP(5) Network configuration IFCFG-DHCP(5)
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
globally configured in /etc/sysconfig/network/dhcp. When appropriate,
examples are given in parentheses, and default values will either be
explicitly mentioned, or will be marked by a "*". Please note, that to
override any of the variables for a 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 open new
windows anymore, then this should be "no". If it happens during
booting it won't be a problem and you can safely 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, require the hostname option field con-
taining a specific string in the DHCP messages 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 it empty to not send any hostname.
DHCLIENT_FQDN_ENABLED {enabled|disabled|default*| }
Default is to use the FQDN option, when the DHCLIENT_HOST-
NAME_OPTION variable 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
the hostname specified in the DHCLIENT_HOSTNAME_OPTION variable.
Default is to update both when hostname is given or none when
hostname is empty and DHCLIENT_FQDN_ENABLED is set to enabled.
DHCLIENT_FQDN_QUALIFY {yes*|no}
Qualify relative sub-domains/hostname in the DHCLIENT_HOST-
NAME_OPTION variable 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.exam-
ple.net').
DHCLIENT_FQDN_ENCODE {yes*|no}
The FQDN option is encoding hostnames using canonical DNS wire
format by default. This flag permits to enable use of the depre-
cated ascii format limited to a single label (short hostname)
for compatibility purposes with draft implementation, which may
be unsupported and cause 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 only one of them does it.
DHCLIENT_ROUTE_PRIORITY
This option allows to set a metric/priority for DHCPv4 routes.
Default is 0.
DHCLIENT_ROUTE_SET_SRC {no*|yes}
When set to yes, the DHCPv4 IP address is set as the preferred
source in DHCPv4 provided routes.
DHCLIENT_CLIENT_ID
Specifies a client identifier string. By default an id derived
from the hardware address of the network interface is sent as
client identifier.
DHCLIENT_CREATE_CID {|rfc4361|dhcpv6|dhcp6|rfc2132|hwaddr|none|disable}
Overrides the DHCPv4 client-identifier type to use specified in
the wicked-config(5) `create-cid` option, the interface type
specific client-id type and compile time defaults. Note: e.g.
DHCP over Infiniband (IPoIB) mandates an rfc4361 client-id.
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
array of class identifiers, but most DHCP clients/servers aren't
compliant with the specification and send/expect a single string
without proper RFC3004 length-value tuple format instead. When
set to "rfc3004" DHCLIENT_USER_CLASS_ID[SUFFIX] permit an RFC
compliant 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 defined as custom dhcp option (see wicked-config.5
man page).
DHCLIENT_LEASE_TIME
Specifies the lease time (in seconds), that is suggested to the
server. Default is 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 settings provided in its last lease when the DHCP-server is
not reachable and the lease hasn't expired yet. Set this vari-
able 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
address is 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. Should probably set per interface rather than
here. This setting causes a sleep time before DHCP clients are
started regardless of the link status. Note: RFC 2131 speci-
fies, that the DHCP client should wait a random time between 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 variable e.g. to a value
twice as high as the time specified here. Default is 15 sec-
onds.
DHCLIENT_TIMEOUT
The DHCP client will stop processing / fail after this time when
it does not get a reply from the DHCP server. Before you set
this variable, take a look 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
built-in facility names supported by the dhcp4 client modifying
the default options used in requests and to update system set-
tings (via netconfig).
When empty, default settings configured in wicked-config(5) or
built-in defaults are used. The special "default", "all", and
"none" sets enable to request none, the built-in default set or
all supported options, respectively. A "no-" or "-" in the front
of a facility name permit to remove/disable it from the cur-
rently applied set, e.g. "default,-nis" disables request for nis
options. More specific variables as
DHCLIENT_SET_DEFAULT_ROUTE,DHCLIENT_SET_HOSTNAME or the MTU
option have higher precedence.
DHCLIENT_BROADCAST {yes|no*}
Request broadcast responses from dhcp-server.
The default behaviour is to not request broadcast responses for
any type of devices except of Infiniband, where it is enabled by
default and not possible to disable.
DHCPv6 Specific Variables
DHCLIENT6_MODE {auto*|info|managed|prefix}
This option allows to specify the request mode used by the
DHCPv6 client when the BOOTPROTO is set to dhcp or dhcp6, and
overrides the "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.
prefix
Request a prefix for delegation, usable also in combina-
tion with auto and managed mode, i.e. auto+prefix or man-
aged+prefix.
DHCLIENT6_RAPID_COMMIT {yes*|no}
This option allows the DHCPv6 client to indicate its desire to
accept rapid commit leases using two-packet exchange (solicita-
tion, lease ack) instead of the four packet (solicitation,
offer, request, lease ack).
DHCLIENT6_PREFIX_HINT {prefix/length}
Permits to specify an explicit prefix-length (e.g. ::/56) or a
specific prefix with a length (e.g. 2001:db8::/48), that are
sent to the DHCPv6 server as hint when prefix delegation request
mode is enabled in the DHCLIENT6_MODE variable.
DHCLIENT6_ADDRESS_LENGTH {length}
Permits to specify explicit prefix-length to use for the DHCPv6
address, e.g. 64 to use address as 2001:db8::1/64 or 80 for
2001:db8::1/80. When 0 or unspecified (default), prefix-length
of the smallest on-link prefix (highest /length number) in the
IPv6 router advertisement matching the address is used or 128
(see also rfc5942).
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 to open new
windows anymore, then this should be "no". If it happens during
booting it won't be a problem and you can safely 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 it empty to not send any host-
name.
DHCLIENT6_FQDN_ENABLED {enabled|disabled|default*| }
Default is to use the FQDN option, when the DHCLIENT6_HOST-
NAME_OPTION variable provides a hostname. When DHCLIENT6_HOST-
NAME_OPTION is set to AUTO, short hostname from the /etc/host-
name 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
the hostname specified in DHCLIENT6_HOSTNAME_OPTION variable.
Default is to update both when hostname is set or none when
hostname is empty and DHCLIENT6_FQDN_ENABLED is set to enabled.
DHCLIENT6_FQDN_QUALIFY {yes*|no}
Qualify relative sub-domains/hostname in the DHCLIENT6_HOST-
NAME_OPTION variable 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.exam-
ple.net').
DHCLIENT6_CLIENT_ID
This option allows to manually specify a client identifier
(DUID) as a colon separated hex byte string for DHCPv6. It dis-
ables the default behavior to maintain the client-id automati-
cally, see wicked-config(5) and `wicked duid --help` for more
details.
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 defined as 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
settings provided in its last lease when the DHCPv6-server is
not reachable and the lease hasn't expired yet. Set this vari-
able 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 address is 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 available and then ~1 second as specified by
RFC3315. This setting allows override to use a non-standsrd
initial delay. Default is 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 variable e.g. to a value
twice as high as the time specified here. Default is 15 sec-
onds.
DHCLIENT6_TIMEOUT
The DHCPv6 client will stop processing / fail after this time
when it does not get a reply from the DHCPv6 server. Before you
set this variable, take a look at DHCLIENT6_WAIT_AT_BOOT allow-
ing 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
built-in facility names supported by the dhcp6 client modifying
the default options used in requests and to update system set-
tings (via netconfig).
When empty, default settings configured in wicked-config(5) or
built-in defaults are used. The special "default", "all", and
"none" sets enable to request none, the built-in default set or
all supported options, respectively. A "no-" or "-" in the front
of a facility name permit to remove/disable it from the cur-
rently applied set, e.g. "default,-nis" disables request for nis
options. The more specific variable DHCLIENT6_SET_HOSTNAME has
higher precedence.
COPYRIGHT
Copyright (C) 2014 SUSE LINUX Products GmbH, Nuernberg, Germany.
BUGS
Please report bugs at <https://bugzilla.novell.com/index.cgi>
AUTHOR
Marius Tomaschewski -- wicked
SEE ALSO
/etc/sysconfig/network/dhcp, wicked(8).
wicked September 2014 IFCFG-DHCP(5)
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