Execute command upon interface initialization?

[J65nko]

On 4/17/07, Ido Admon <rhingael at mscc.huji.ac.il> wrote:
> Hello list,
> I couldn't find any way to execute an arbitrary command upon network
> interface initialization. My situations is that I have and ethernet card
> that takes DHCP from a cables provider (not a fixed IP address) and I
> need to update a DynDNS hostname everytime it does (everytime the IP
> changes).
> I couldn't find a way to execute shell commands using the rc system or
> dhclient, what did I miss?

You can use a '/etc/start_if.<nic>' file. If your NIC is fxp0 then a
'/etc/start_if.fxp0' file will be run or sourced by the 'rc' system.

In http://www.bsdforums.org/forums/showthread.php?t=34607 this type of
file is used to set a MTU of 1492