48 lines
2.0 KiB
D
48 lines
2.0 KiB
D
|
The /etc/dhcp/dhclient.d directory allows other packages and system
|
||
|
|
administrators to create application-specific option handlers for dhclient.
|
||
|
|
|
||
|
|
When dhclient is run, any option listed in the dhcp-options(5) man page can
|
||
|
|
be requested. dhclient-script does not handle every option available
|
||
|
|
because doing so would make the script unmaintainable as the components
|
||
|
|
using those options might change over time. The knowledge of how to handle
|
||
|
|
those options should be under the responsibility of the package maintainer
|
||
|
|
for that component (e.g., NTP options belong in a handler in the ntp
|
||
|
|
package).
|
||
|
|
|
||
|
|
To make maintenance easier, application specific DHCP options can be handled
|
||
|
|
by creating a script with two functions and placing it in /etc/dhcp/dhclient.d
|
||
|
|
|
||
|
|
The script must follow a specific form:
|
||
|
|
|
||
|
|
(1) The script must be named NAME.sh. NAME can be anything, but it makes
|
||
|
|
sense to name it for the service it handles. e.g., ntp.sh
|
||
|
|
|
||
|
|
(2) The script must provide a NAME_config() function to read the options and
|
||
|
|
do whatever it takes to put those options in place.
|
||
|
|
|
||
|
|
(3) The script must provide a NAME_restore() function to restore original
|
||
|
|
configuration state when dhclient stops.
|
||
|
|
|
||
|
|
(4) The script must be 'chmod +x' or dhclient-script will ignore it.
|
||
|
|
|
||
|
|
The scripts execute in the same environment as dhclient-script. That means
|
||
|
|
all of the functions and variables available to it are available to your
|
||
|
|
NAME.sh script. Things of note:
|
||
|
|
|
||
|
|
${SAVEDIR} is where original configuration files are saved. Save your
|
||
|
|
original configuration files here before you take the DHCP provided
|
||
|
|
values and generate new files.
|
||
|
|
|
||
|
|
Variables set in /etc/sysconfig/network, /etc/sysconfig/networking/network,
|
||
|
|
and /etc/sysconfig/network-scripts/ifcfg-$interface are available to
|
||
|
|
you.
|
||
|
|
|
||
|
|
See the scripts in /etc/dhcp/dhclient.d for examples.
|
||
|
|
|
||
|
|
NOTE: Do not use functions defined in /sbin/dhclient-script. Consider
|
||
|
|
dhclient-script a black box. This script may change over time, so the
|
||
|
|
dhclient.d scripts should not be using functions defined in it.
|
||
|
|
|
||
|
|
--
|
||
|
|
David Cantrell <dcantrell@redhat.com>
|