iptables and dynamic ip

[Benedict Verheyen <benedict.verheyen@pandora.be>]

Hello,

i have a question regarding iptables and dynamic ip's.
i noticed in a lot of scripts that they don't use the ip address of the
interfaces but rather use eth0 and eth1 for instance.
Now on my server, i have eth0 which gets an ip from my isp via DHCP and
on eth1 i run a dhcp server for my internal lan.

If i start an iptable script and refer in my rules there to the external
interface as eth0, will it still work properly after the ip changes of
eth0 during it's uptime or will this make the server unreachable?
For instance i want to allow ssh in on the server from the outside, if
the ip changes, will this "break" the connection?

Thanks