File dhcpcd-1-vs-3 of Package dhcpcd.import4358
Common Options:
* interface
-c script
dhcpcd will try to execute script instead of the default script /etc/dhcpcd.sh every time it configures
or brings down the interface. See the description of dhcpcd.sh script in FILES section below.
-h hostname
specifies a string used for the hostname option field when dhcpcd sends DHCP messages. Some DHCP servers,
notably those used by @Home Networks, require the hostname option field containing a specific string in
the DHCP messages from clients. When combined with the -F switch, specifies the string used for the FQDN
option field instead of the hostname option field. We send the current
hostname by default. To send no hostname, use -h ''.
-k Sends SIGHUP signal to the dhcpcd process associated with the specified interface if one is currently running.
-n Sends SIGALRM signal to the dhcpcd process that is currently running which forces dhcpcd to try to renew the lease.i
If dhcpcd is not running, the flag is ignored and dhcpcd follows the normal
startup procedure.
-H Forces dhcpcd to set hostname of the host to the hostname option supplied by DHCP server. By default dhcpcd will NOT
set hostname of the host to the hostname option received from DHCP server
unless the current hostname is blank, (none) or localhost. If no hostname is returned by the DHCP server then we attempt to lookup the hostname via DNS.
-I clientID
Specifies the client identifier string. dhcpcd uses the default client identifier (MAC address of the network interface) if it is not specified.
-M Prevents dhcpcd from setting the MTU provided by the DHCP server.
-N Prevents dhcpcd from replacing /etc/ntp.conf
-R Prevents dhcpcd from replacing /etc/resolv.conf or using resolvconf.
-T dhcpcd sends out a DHCP_DISCOVER message and then prints the values returned to stdout. It does not
configure the interface or touch the .info files
-K Keep the searchlist from an existing resolv.conf when replacing the file.
dhcpcd will add it to the domainname received from the DHCP server.
-Y Prevents dhcpcd from replacing /etc/yp.conf
-D Forces dhcpcd to set domainname of the host to the domainname option supplied by DHCP server.
Slightly Modified Options:
-H set hostname to the full FQDN
-HH strip the domain if it matches a given domain in our DHCP message
-HHH strip the domain regardless
-HHHH force hostname lookup even if given a hostname in our DHCP message
-HHHHH same as above, but strip the domain if it matches
-HHHHHH same as above, but strip the domain regardless
-i vendorClassID
Specifies the vendor class identifier string. The default is dhcpcd-<version>.
dhcpcd-1: Specifies the vendor class identifier string. dhcpcd uses the default vendor class identifier
string (system name, system release, and machine type) if it is not specified.
-l leasetime
Specifies (in seconds) the recommended lease time to the server. (Note that the server can override
this value if it sees fit). This value is used in the DHCP_DISCOVER message. Use -1 for an
infinite lease time. We don't request a specific lease time by default. If we do not receive a lease
time in the DHCP_OFFER message then we default to 1 hour.
dhcpcd-1: Specifies (in seconds) the recommended lease time to the server. (Note that the server can override
this value if it sees fit). This value is used in the DHCP_DISCOVER message. The default is
infinite (0xffffffff).
-t timeout
Specifies (in seconds ) for how long dhcpcd will try to get an IP address. The default is 20 seconds.
dhcpcd will not fork into background until it gets a valid IP address in which case dhcpcd
will return 0 to the parent process. In a case dhcpcd times out before receiving a valid IP address
from DHCP server dhcpcd will return exit code 1 to the parent process. Setting the timeout to
zero disables it: dhcp will keep trying forever to get a lease, and if the lease is lost, it will try forever to get another.
dhcpcd-1: The default is 60 seconds.
-G
Prevents dhcpcd from installing default routes provided by DHCP server.
dhcpcd-1: -G [gateway]
Prevents dhcpcd from installing default routes provided by DHCP server. If optional gateway ip address parameter
is supplied then use it for default route.
Modified Options:
-d Echos debugging and information messages to the console. Subsequent debug options stop dhcpcd from daemonising
dhcpcd-1: With this flag dhcpcd will syslog(LOG_DEBUG,...) messages for about every step it does.
-r ipaddr
Sends DHCP_REQUEST message requesting to lease IP address ipaddr. The ipaddr parameter must be in
the form xxx.xxx.xxx.xxx. If we are not given an ipaddr then we try to use the first one assigned
to the interface if present, otherwise the last address we leased for the interface, otherwise we
return an error. This effectively doubles the timeout period, as if we fail to get this IP address
then we enter the INIT state and try to get any IP address.
dhcpcd-1: -r
-r Makes dhcpcd RFC1541 (obsolete) compliant. dhcpcd is RFC2131 compliant unless this option is specified.
-s ipaddr[/cidr]
Exactly like -r, but sends DHCP_INFORM instead. This requires the interface to be configured with
the ipaddr/cidr first. When we DHCP_INFORM, we don't request or respect any lease times. However,
we do re-inform by the lease time specified by -l if given.
dhcpcd-1: -s [ipaddr]
Sends DHCP_INFORM message to DHCP server using ipaddr. The optional ipaddr parameter must be in the
form xxx.xxx.xxx.xxx. If no ipaddr parameter is given on the command line dhcpcd will use
the IP address currently assigned to the interface. If there is no IP address currently
assigned to the interface dhcpcd will use previously obtained IP address stored in <Con-
figDir>/dhcpcd-<interface>.cache file.
-L Prevents dhcpcd from probing for IPV4LL addresses. IPV4LL is otherwise known as ZeroConf or APIPA
and is RFC 3927.
dhcpcd-1: -L <ConfigDir>
dhcpcd will use <ConfigDir> directory instead of default /var/lib/dhcpcd/ to store configuration information.
New Options:
-a Do an ARP check on the IP address give to us by the DHCP server. We may need to do this if a client on the same network
segment has the same IP address, however we do not do this by default as
most DHCP servers test the IP briefly with an ICMP Echo request before assigning the IP address.
-m metric
Routes will be added with the given metric. The default is 0. On some systems such as FreeBSD the interface is given the metric.
-p Stops dhcpcd from removing the interface configuration when it is terminated with the SIGTERM signal. This is useful
when a host is running with an NFS-mounted root filesystem over an interface controlled by DHCP.
It should not be used except in those circumstances, since if dhcp is stopped it can no longer down
an interface at the end of its lease period when the lease is not renewed.
-u userClass
Tags the DHCP message with the specified user class. DHCP servers can use these fields to send back
different information instead of grouping by fixed hardware addresses. You can specify more
than one user class, but the total length must be less than 255 characters, -1 character for each user class.
-F none|ptr|both
Forces dhcpcd to request the DHCP server update the DNS using the FQDN option instead of the Hostname option.
The name used by this option is specified with the -h switch, which must be present.
If the -h switch is not present, the FQDN option is ignored. The name should be fully qualified,
although servers usually accept a simple name. both requests that the DHCP server update both
the A and PTR records in the DNS. ptr requests that the DHCP server updates only the PTR record
in the DNS. none requests that the DHCP server perform no updates. dhcpcd does not perform any
DNS update, even when the server is requested to perform no updates. This can be easily
implemented outside the client; all the necessary information is recorded in the
/var/lib/dhcpcd/dhcpcd-<interface>.info file.
--netconfig
Forces dhcpcd to use the SuSE netconfig tool. This option turn on following options: -N, -R, -Y and sets -c to
/etc/sysconfig/network/scripts/dhcpcd-netconfig-hook.
Missing in dhcpcd-3.0
-B Requests broadcast response from DHCP server.
-C Forces dhcpcd to calculate checksum on received packets.
-S Forces dhcpcd to send second DHCP_DISCOVER message even after receiving DHCP_OFFER on the first one.
Some DHCP servers expect the client to send second DHCP_DISCOVER message before replying on
DHCP_REQUEST.
The -S option has in dhcpcd 3.2.3 a totaly other meaning:
-S, --mscsr
Microsoft have their own code for Classless Static Routes (RFC 3442). You can use this option
to request this as well as the normal CSR. Another instace of this option only requests the
Microsoft CSR to prevent DHCP message over-running its maximum size. DHCP server administra-
tors should update their CSR code from the Microsoft specific one to the RFC compliant one as
the content is fully compatible.
-z <reboottimeout>
Specifies (in seconds) for how long dhcpcd will stay in the INIT-REBOOT state (requesting the
last IP address it had again). The default is 5 seconds, and after this time, dhcpcd will go into
the INIT state (broadcasting DHCPDISCOVERs). Note that dhcpcd also makes this transition when a DHCPNAK
is received. The timeout can prevent dhcpcd from being stuck in this state, when there is
no server which is configured to be authoritative to reply with DHCPNAK, and a long -t timeout is used
(to keep dhcpcd running. (This timeout is only relevant when there is already a cache file
from a previous run for the interface.)
-w <windowsize>
Specifies the window size for the gateway route. Default = 32768.
