From Mycomputer Notes

Revision as of 21:46, 13 November 2006

Configuring NAT & PAT

Static Translations

Stattic Trasnlation are entered direclty into the configuration and are always entered in the translation table. To configured static inside source address translation perform the task below:

• - Establish static translation between an inside local address and an insie global address in Global Configuration Mode.

Router(Config)#ip nat inside source static <LOCAL-IP> <GLOBAL-IP>

• - Enter the interface mode and specify the inside interface & Mark the interface as connected to the inside

Router(config)#interface <TYPE> <NUMBER>
Router(config)#ip nat inside

• - Specify the outside inteface & Mark the interface as connected to the outised

 Router(config)#interface <TYPE> <NUMBER>
 Router(config)#ip nat outside

Dynamic Translations

Access lists are used by NAT to select addresses for dynamic translation, dynamic translation used the addresses permitted by the access list to be translated; only those addresses are to be translated. Cisco advises againtst configuring access list referenced by NAT command with permit any command. Using permit any can result in NAT consuming too many router resources, which can cause network problems. To configure dynamic inside source address translation, perform the tasks below

Router(config)#access-list 1 permit 10.0.0.0 0.0.255.255
Router(config)#ip nat inside source list 1 pool <POOL-NAME>

• - Enter global configuration mode and define a pool of global addresses to be allocated as needed.

Router(config)#ip nat pool <POOL-NAME><START-IP><END-IP> netmask <NETMASK>

• - Define a standard access list permitting those addresses that are to be translated

Router(config)#access-list <ACL-NUMBER> permit <IP-SOURCE> <WILDCARD>

• - Establish dynamic source translating specifying the access list defined in prior step.

Router(config)#ip nat inside source list <ACL-NUMBER> pool <POOL-NAME>

• - Enter the interface mode and specify the inside interface & Mark the interface as connected to the inside

Router(config)#interface <TYPE> <NUMBER>
Router(config)#ip nat inside

• - Specify the outside inteface & Mark the interface as connected to the outised

 Router(config)#interface <TYPE> <NUMBER>
 Router(config)#ip nat outside

Configuring PAT

Overloading is configured when an IPS has allocated one public ip address to an entire private network.

Define a standard IP access list permitting those inside local addresses that are to be translated.

Router (config)#access-list 1 permit 10.0.0.0 0.0.255.255

Establish overload translation by specifying the IP address to be overloaded as that assigned to an outside interface.

Router (config)#ip nat inside source list 1 interface serial0/0 overload.

Follow the steps below to configured overloading: The first step os tje same as when configuring a dynamic translation.

• - Define a standard access list permitting those addresses that are to be translated.