Question regarding dhclient-script exit-hooks
bryan.mesich at ndsu.edu
Tue Dec 16 23:59:13 UTC 2008
Good evening to all on the dhcp mailing list,
I'm trying to use the exit-hooks functionality dhclient-script
provides to update a NAT entry in my iptables configuration. The
system in question is being used as a gateway for others to gain
access to the outside world. My iptables configuration is as
-A POSTROUTING -o eth0 -j SNAT --to-source xxx.xxx.xxx.xxx
Where the IP address xxx.xxx.xxx.xxx is the IP address the cable
modem has issued to the system. When the system renews a new IP
address, the NAT entry needs to be changed as well. Reading the
dhclient-script man page, there are a number of reasons why
dhclient-script might be called. The documented reasons are:
MEDIUM, PREINIT, BOUND, RENEW, REBIND, REBOOT, EXPIRE, FAIL,
STOP, RELEASE, NBI and TIMEOUT
I'm a little confused which reason(s) I should be checking for.
If I down the interface and then bring it up via "ifup eth0",
dhclient-script is executed twice (PREINIT, and REBOOT). This
makes sense upon reading the documentation.
My question is, which $reason should I be checking for in my
dhclient-exit-hooks script to detect a change in my IP address?
Is having reason=RENEW good enough?
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