I can't help you with guarddog, but i want to recommend that if your router supports it, forward a diffrent port for ssh. What i mean is, make it so when you remotely ssh in, you are aiming at a port other than 22, such as 422, or 8022, or any non-standard ssh port. Have the router then forward that traffic to port 22 on your computer. I say this because there are a lot of script kiddies out there with brute force password guessers, you will see all their attempts in /var/log/messages.
Also, since you are using a software firewall along with your hardware firewall (router) i assume you are the paranoid type (a good thing) so you will want to edit /etc/ssh/sshd_config and add something like this:
AllowUsers <your username>
DenyGroups root bin daemon apache (etc...)
DenyUsers root bin daemon apache (etc...)
These two precautions should make it harder for someone to randomly find your computer (with nmap looking for port 22 open on a set of IP addresses) and if they do guess your "secret" port for ssh they wont be able to try to login as root with a password guesser.
I hope i helped a bit, though i know nothing about guarddog.