If you get this issue when you load the Pix, you may not have a private key.
Type: show ca mypubkey rsa in enable mode and see if you have a key.
I had this problem occur after enabling 3des on a Pix 501.
To generate a new key, go into Global Confiuration mode (Conf T) and type the following:
ca gen rsa key 1024
ca save all
This will create a new key if you don’t have one, or clear out the old one if you already do.
It is best to create a domain name if you don’t have one already using the domain-name command.
I became a huge fan of the Snapgear range of firewalls, in particular the SG560 about 2 years ago.The Snapgear SG560 is around the $600 mark in Australia, and this makes it the bargain of the decade when it comes to securing your network and also connecting your branch offices with IPSEC VPN’s.
Should you have to reset the SG560 back to it’s factory settings, simply press the reset button on the back of the device twice quickly with a pen or pencil. All the lights will flash, and the device will be set back to the way it came from the factory with the IP address of 192.168.0.1and with a username of root and a password of default.
DHCP will not be turned on, so simply set the IP address of the device that you are connecting to the Snapgear via ethernet with to 192.168.0.2 with a subnet mask of 255.255.255.0 and you will be able to start configuring your freshly reset firewall.