NAT/PAT with defined outside source ports

[Antonio_1_2]

Hello,

is there a way to configure PAT/NAT many to one in a way that inside source addresses are translated to one outside IP address but always to the same outside ports

i.e.

LAN 172.16.1.0/24 ---> to WAN 192.168.100.100/32 ports 10001 -13000

but with restriction that every IP from LAN always has the same outside source port

172.16.0.1 ----> 192.168.100.100 10001

172.16.0.2 ----> 192.168.100.100 10002

172.16.0.3 ----> 192.168.100.100 10003

-----------------------------

172.16.0.255 ----> 192.168.100.100 10255

If I am not mistaken if I configure NAT overload (PATH) with port restriction feature on a router,

any inside IP address (LAN side) will be translated to (specific) configured outside IP address and ports will be dynamicaly assigned.

i.e. 172.16.0.1 will  be translated to 192.168.100.100 but port number can be any from range 10001 - 10300 which is not used in NAT table at the moment.

Does anybody know if there is a way to configure it?

Regards,

A.

[Chuan Liu]

Hi Antonio,

This is not possible. Think of one PC, say, 172.16.0.1. When it browses one website, it has a dynamic source port; when it opens another TCP/IP session to outside world, another dynamic source port is used, and so on. These concurrent sessions are working because the NAT router dynamically maps ports. One port on the NAT router maps to only one port on an inside ip address.

Regards.

[Antonio_1_2]

Hi Chuan,

Thank you,

A.