The PIX 525 Firewall comes with a restricted license and with an unrestricted license. Both are described here.
PIX 525 Firewall (with restricted license):
PIX 525 Firewall (with unrestricted license):
The PIX 525 Firewall supports all available versions of the PIX software.
For information on installing additional Ethernet cards in the PIX 525 Firewall, refer How to install additional Ethernet interface cards in a PIX Firewall.
For further information on the interfaces that can be installed in the PIX 525 Firewall, refer to the Installing a Circuit Board on the PIX 525 section of the PIX 525 Hardware Installation Guide.
For more information on the minimum requirements to install PIX software 7.x, refer to Cisco PIX Security Appliance Release Notes Version 7.2.
For the procedure on how to set up the PIX Firewall in failover mode, refer to Using PIX Firewall Failover.
1-port Fast Ethernet (1FE)
4-port Fast Ethernet (4FE)