One of my customers sent their PIX 506E to another office and bought a501, which they asked me to configure. I used the console port to load the old configuration including a command to enable ssh from my notebook: ssh 192.168.0.201 255.255.255.255 inside
When I tried to connect to the PIX from the network, Putty flashed and then immediately terminated. However, I could telnet to it after enabling that. I'm wondering if the 501 uses a different version of SSH than the 506, which would require adjusting one of the SSH parameters for the saved Putty session.