Hello - I have just had to replace a dead (finally) PIX 520. Untill my company can afford it, I am using a PIX 501. The outside interface is connected to a Verizon DSL router, and the inside through a 2950 and an old 1600 series router. Problem is ever since I went to the 501, no one behind the firewall can get to the internet. I can ping internet sites from the 501 itself, but nothing from behind it. I know it must be something simple, but I can't figure it out. I am attaching the configs for the router and firewall
Try this configuration.
no global (outside) 1 XX.XX.XX.XX netmask 255.255.255.255
global (outside) 1 interface
If your xx.xx.xx.xx in the global configuration is the outside interface address then you should use the keyword interface for PAT instead of address.