DHCPCD-RUN-HOOKS(8) System Manager's Manual DHCPCD-RUN-HOOKS(8)
NAME
dhcpcd-run-hooks — DHCP client configuration script
DESCRIPTION
dhcpcd-run-hooks is used by dhcpcd(8) to run any system and user defined
hook scripts. System hook scripts are found in
/usr/lib/dhcpcd/dhcpcd-hooks and the user defined hooks are
/etc/dhcpcd.enter-hook. and /etc/dhcpcd.exit-hook. The default install
supplies hook scripts for configuring /etc/resolv.conf 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.
The hooks scripts are loaded into the current shell rather than executed
in their own process. This allows each hook script, such as
/etc/dhcpcd.enter-hook to customise environment variables or provide al-
ternative functions to hooks further down the chain. As such, using the
shell builtins exit, exec or similar will cause dhcpcd-run-hooks to exit
at that point.
Each time dhcpcd-run-hooks is invoked, $interface is set to the inter-
face that dhcpcd is run on and $reason is set to the reason why
dhcpcd-run-hooks 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 word old_. dhcpcd can
display the full list of variables it knows about by using the -V,
--variables argument.
Here's a list of reasons why dhcpcd-run-hooks could be invoked:
PREINIT dhcpcd is starting up and any pre-initialisation re-
quired should be performed now.
CARRIER dhcpcd has detected the carrier is up. This is gener-
ally just a notification and no action need be taken.
NOCARRIER dhcpcd lost the carrier. The cable may have been un-
plugged or association to the wireless point lost.
NOCARRIER_ROAMING
dhcpcd lost the carrier but the interface configura-
tion is persisted. The OS has to support wireless
roaming or IP Persistence for this to happen.
INFORM | INFORM6 dhcpcd informed a DHCP server about its address and
obtained other configuration details.
BOUND | BOUND6 dhcpcd obtained a new lease from a DHCP server.
RENEW | RENEW6 dhcpcd renewed its lease.
REBIND | REBIND6 dhcpcd has rebound to a new DHCP server.
REBOOT | REBOOT6 dhcpcd successfully requested a lease from a DHCP
server.
DELEGATED6 dhcpcd assigned a delegated prefix to the interface.
IPV4LL dhcpcd obtained an IPV4LL address, or one was removed.
STATIC dhcpcd has been configured with a static configuration
which has not been obtained from a DHCP server.
3RDPARTY dhcpcd is monitoring the interface for a 3rd party to
give it an IP address.
TIMEOUT dhcpcd failed to contact any DHCP servers but was able
to use an old lease.
EXPIRE | EXPIRE6 dhcpcd's lease or state expired and it failed to ob-
tain a new one.
NAK dhcpcd received a NAK from the DHCP server. This
should be treated as EXPIRE.
RECONFIGURE dhcpcd has been instructed to reconfigure an inter-
face.
ROUTERADVERT dhcpcd has received an IPv6 Router Advertisement, or
one has expired.
STOP | STOP6 dhcpcd stopped running on the interface.
STOPPED dhcpcd has stopped entirely.
DEPARTED The interface has been removed.
FAIL dhcpcd failed to operate on the interface. This nor-
mally happens when dhcpcd does not support the raw in-
terface, which means it cannot work as a DHCP or Zero-
Conf client. Static configuration and DHCP INFORM is
still allowed.
TEST 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.
ENVIRONMENT
dhcpcd will clear the environment variables aside from $PATH. The fol-
lowing variables will then be set, along with any protocol supplied
ones.
$interface the name of the interface.
$protocol the protocol that triggered the event.
$reason as described above.
$pid the pid of dhcpcd.
$ifcarrier the link status of $interface: unknown, up
or down.
$ifmetric $interface preference, lower is better.
$ifwireless 1 if $interface is wireless, otherwise 0.
$ifflags $interface flags.
$ifmtu $interface MTU.
$ifssid the SSID the interface is connected to.
$interface_order A list of interfaces, in order of prefer-
ence.
$if_up true if the interface is up, otherwise
false. This is more than IFF_UP and may
not be equal.
$if_down true if the interface is down, otherwise
false. This is more than IFF_UP and may
not be equal.
$af_waiting Address family waiting for, as defined in
dhcpcd.conf(5).
$profile the name of the profile selected from
dhcpcd.conf(5).
$new_delegated_dhcp6_prefix space-separated list of delegated prefixes.
FILES
When dhcpcd-run-hooks runs, it loads /etc/dhcpcd.enter-hook, any scripts
found in /usr/lib/dhcpcd/dhcpcd-hooks in lexical order, then finally
/etc/dhcpcd.exit-hook.
SEE ALSO
dhcpcd(8)
AUTHORS
Roy Marples <roy@marples.name>
BUGS
Please report them to https://roy.marples.name/projects/dhcpcd
SECURITY CONSIDERATIONS
dhcpcd will validate the content of each option against its encoding.
For string, ascii, raw or binhex encoding it's up to the user to vali-
date it for the intended purpose.
When used in a shell script, each variable must be quoted correctly.
Debian August 31, 2022 DHCPCD-RUN-HOOKS(8)
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