The Cisco ASA 5500 series is the descendant of the older Cisco PIX 500 series firewall which was very successful in network security implementations. The ASA is not just a pure hardware firewall, rather is a full featured security appliance. What we mean by that is that the ASA hardware appliance, in addition to being a solid network firewall, is capable of working also as a content inspection engine, antivirus, antispam, IDS/IPS engine, VPN device, SSL device etc. The extra security functionality of the firewall is achieved with add-on module cards which offer the additional security features.
The Cisco ASA has one of the biggest market shares in the hardware firewall appliance market, together with Juniper Netscreen, Checkpoint, SonicWall, WatchGuard etc.
The ASA 5500 series is comprised from seven models, as we will see below.