DHCP client configuration script
is used by
to run any system and user defined hook
scripts. System hook scripts are found in
and the user
defined hooks are /etc/dhcpcd.enter-hook
. The default
install supplies hook scripts for configuring
and the hostname. Your
distribution may have included other hook scripts to say configure ntp or
ypbind. A test hook is also supplied that simply echos the dhcp variables to
the console from DISCOVER message.
is set to the interface that
is run on and
is to the reason why
was invoked. DHCP
information to be configured is held in variables starting with the word new_
and old DHCP information to be removed is held in variables starting with the
can display the full list
of variables it knows how about by using the
Here's a list of reasons why
could be invoked:
- dhcpcd is starting up and any pre-initialisation should be done.
- dhcpcd has detected the carrier is up. This is generally just a
notification and no action need be taken.
- dhcpcd informed a DHCP server about it's address and obtained other
- dhcpcd obtained a new lease from a DHCP server.
- dhcpcd renewed it's lease.
- dhcpcd has rebound to a new DHCP server.
- dhcpcd successfully requested a lease from a DHCP server.
- dhcpcd failed to contact any DHCP servers but did obtain an IPV4LL
- dhcpcd has been configured with a static configuration which has not been
obtained from a DHCP server.
- dhcpcd is monitoring the interface for a 3rd party to give it an IP
- dhcpcd failed to contact any DHCP servers but was able to use an old
- dhcpcd's lease or state expired and it failed to obtain a new one.
- dhcpcd received a NAK from the DHCP server. This should be treated as
- dhcpcd has been instructed to reconfigure an interface.
- dhcpcd lost the carrier. The cable may have been unplugged or association
to the wireless point lost.
- dhcpcd failed to operate on the interface. This normally happens when
dhcpcd does not support the raw interface, which means it cannot work as a
DHCP or ZeroConf client. Static configuration and DHCP INFORM is still
- dhcpcd stopped running on the interface.
- The interface has been removed.
- dhcpcd has been asked to dump the last lease for the interface.
- dhcpcd received an OFFER from a DHCP server but will not configure the
interface. This is primarily used to test the variables are filled
correctly for the script to process them.
- dhcpcd has received an IPv6 Router Advertisment, or one has expired.
runs, it loads
and any scripts
found in /lib/dhcpcd/dhcpcd-hooks
lexical order and then finally
Please report them to
Little validation of DHCP options is done in dhcpcd itself. Instead, it is up to
the hooks to handle any validation needed. To this end, some helper functions
are provided, such as valid_domainname as used by the
hook to ensure that the
hostname is not set to an invalid value. valid_path is also provided, but is
currently unused by a stock hook script.