Firewalls have traditionally provided perimeter security by maintaining stateful control of all connections between connected network segments. Today, more and more customers are looking to the firewall for VPN services in addition to access control. With a VPN, remote users or distributed branches can securely access corporate networks at a low cost. Using the Internet for access dramatically reduces the telecommunications costs associated with previous leased-line or other dedicated networks. Companies also no longer need to maintain large modem banks and access servers - a large capital outlay and administrative headache - to handle remote dial-in users. With just a local phone call to an Internet Service Provider (ISP), users can securely access private corporate intranets over the Internet.The Cisco PIX 525 Firewall enables secure private communications over the Internet or any IP network. It integrates key features of VPNs - tunneling, data encryption, security, and firewalling - to provide a secure, scalable platform to better and more cost-effectively accommodate remote-access, remote-office, and extranet connectivity using public data services.The Cisco PIX product line offers users with a full-suite of security appliances, all of which easily interoperate with a PIX 525 performing as Enterprise Headquarter head-end appliance. The PIX 525 also provides users with a complete implementation of IPsec standards which ensures confidentiality, integrity, and authenticity. For secure data encryption, Cisco's implementation of IPsec supports both the 56-bit Data Encryption Standard (DES) and 168-bit Triple DES algorithms.The Cisco PIX 525 Unrestricted model extends the capabilities of the security appliance with support for stateful failover, additional LAN interfaces, and increased VPN throughput via integrated hardware-based VPN acceleration.