The translation table contains layer 3 IP address mappings and is commonly known as the xlate table. Use the show xlate command to display the contents and the clear xlate command to clear the contents of the table.
The connection table contains layer 4 TCP or UDP sessions. Use the show conn command to display the contents and the clear conn command to clear the contents of the table.
To allow traffic inbound, you need to use an ACL or a conduit with a static mapping.
NAT is dynamic inside to outside layer 3 IP address-to-IP address mapping; PAT is dynamic inside to outside layer 3 plus layer 4 IP address and port-to-IP and port mapping.
The static command is used to create a one-to-one IP address mapping or a one-to-one port to address mapping.
The nat 0 command tells the PIX not to perform translation on an IP address as it passes through the firewall. It is commonly used when public addresses are on the inside of a firewall and don't need translating.
The static or NAT parameter called max_conns is used to define the maximum TCP connections permitted.
The static or NAT em_limit parameter sets the maximum number of embryonic or half- open connections, which is used to prevent SYN attacks.