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Cisco PIX (Private Internet eXchange) is one of the most popular IP firewalls and network address translation (NAT) appliances.
The PIX is a firewall appliance based on a hardened, specially built operating system, PIX OS, minimizing possible OS-specific security holes.
The PIX runs a custom-written proprietary operating system originally called Finesse (Fast InterNEt Server Executive), but now the software is known simply as PIX OS. It is classified as a network layer firewall with stateful inspection, although technically the PIX would more precisely be called a Layer 4, or Transport Layer Firewall, as its access is not restricted to Network Layer routing, but socket based connections (a port and an IP Address – Port communications occur at Layer 4).
PIX firewalls provide a wide range of security and networking services including:
- Network Address Translation (NAT) or Port Address Translation (PAT)
- content filtering (Java/ActiveX)
- URL filtering
- IPsec VPN
- support for leading X.509 PKI solutions
- DHCP client/server
- PPPoE support
- advanced security services for multimedia applications and protocols including Voice over IP (VoIP), H.323, SIP, Skinny and Microsoft NetMeeting
- AAA (RADIUS/TACACS+) integration
