CCIE Practical Studies: Security (CCIE Self-Study)

Security Levels and Address Translation

The PIX Firewall treats its interfaces according to the level of trust. The levels range from 0 to 100; 0 is the least trusted and 100 is the most trusted interface. By default, the inside interface is assigned the level of 100 and the outside interface the level of 0 (see Figure 23-1). The inside interface is connected to the network that needs to be protected. The outside interface is attached to the public network (the Internet) that the inside interface needs protection against.

Figure 23-1. PIX Firewall Interfaces and Security Levels

This level assignment results in the way the PIX Firewall handles ...