Sorry for the necro, but I bet others have came across SonicWall before. At the log in screen of sonicwall (I think it is the default gateway, don't have the system in front of me though), look at the source. There are two md5's that I believe are the username and pass to log into sonicwall directly. You will need to crack the md5s though. On a side note, since this is your dad, you can use a key-logger or other method of getting a password. After you have a password for something he uses, I bet that will be the same pass for most everything he uses. You could also try the default log-ins, I.E. admin/admin admin/password etc... As a last resort, a proxy should work as well.