PAR - When you need to implement traffic redirections using NAT
Share this page:You can define the traffic redirection using Static Entries, but there is a trick.
For example you want all the http traffic DESTINED FOR s0/0.5 to be REDIRECTED to the IP 10.1.123.3 instead.
You can configure this by defining the static NAT:
R1(config)#ip nat inside source static tcp 10.1.123.3 80 int s0/0.5 80
Make sure you understand how this command works, because it´s quite a complicated principle because it works a bit “upside down”.
So when you try to telnet R1s IP using the port 80, from the router on the s0/0.5 side (R4):
R4#telnet 131.1.14.1 80
Trying 131.1.14.1, 80 … Open
You see the following debug:
*Nov 6 15:54:48.703: NAT*: s=131.1.14.4, d=131.1.14.1->10.1.123.3 [23053] <- 131.1.14.4: Router from where we telnet
*Nov 6 15:54:48.707: NAT*: s=10.1.123.3->131.1.14.1, d=131.1.14.4 [31747] <- NATed and FWD-ed to to 10.1.123.3
*Nov 6 15:54:48.735: NAT*: s=131.1.14.4, d=131.1.14.1->10.1.123.3 [23054]
*Nov 6 15:54:48.739: NAT*: s=131.1.14.4, d=131.1.14.1->10.1.123.3 [23055]
*Nov 6 15:55:48.739: NAT*: s=10.1.123.3->131.1.14.1, d=131.1.14.4 [31748]
*Nov 6 15:55:48.767: NAT*: s=131.1.14.4, d=131.1.14.1->10.1.123.3 [23056]
*Nov 6 15:56:48.763: NAT*: s=10.1.123.3->131.1.14.1, d=131.1.14.4 [31749]
*Nov 6 15:56:48.791: NAT*: s=131.1.14.4, d=131.1.14.1->10.1.123.3 [23057]
*Nov 6 15:57:12.959: NAT*: s=131.1.14.4, d=131.1.14.1->10.1.123.3 [23058]
*Nov 6 15:57:13.127: NAT*: s=131.1.14.4, d=131.1.14.1->10.1.123.3 [23059]
*Nov 6 15:57:13.155: NAT*: s=10.1.123.3->131.1.14.1, d=131.1.14.4 [31750]
*Nov 6 15:57:13.311: NAT*: s=131.1.14.4, d=131.1.14.1->10.1.123.3 [23060]
*Nov 6 15:57:13.507: NAT*: s=10.1.123.3->131.1.14.1, d=131.1.14.4 [31751]