One-to-One Translations

Use static NAT rules to make one-to-one translations between either single pair or multiple pairs of addresses. Most commonly, static NAT rules are used to translate an advertised address for a public server to a different address.

A static NAT rule translates either the source or destination addresses in a packet. In most cases, this means that you will need to define two NAT rules:

1. One to translate the source address when the packet is flowing in one direction.

2. A second rule to translate the destination address when packets are flowing in the other direction.

• Example of Static NAT Rules in One-to-One Translation

  Assume that your public web server has an address of 10.0.0.1 (defined by the address object "private_www") and you want to allow access to this web server through the public address 199.190.177.1 (defined by the address object "public_www"). Assume also that the address Internet represented the Internet addresses.

  To do this requires two static NAT rules, as shown in TABLE 7-1:

  1. The first rule specifies that the destination address public_www (199.190.177.1) is the translated destination address private_www (10.0.0.1). This NAT rule handles packets flowing to the web server.

  2. The second rule specifies that the source address private_www (10.0.0.1) is the translated source address public_www (199.190.177.1). This NAT rule handles packets flowing from the web server.

     Table 7-1 Static NAT Rules

     Type of NAT Rule	Source	Destination	Translated Source	Translated Destination	Comment
     STATIC	"Internet"	"public_www"	"Internet"	"private_www"	Packets to server
     STATIC	"private_www"	"Internet"	"public_www"	"Internet"	Packets from server

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     Note -

     The order of the addresses is reversed in the two rules.

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