10-04-2007 12:51 PM - edited 02-21-2020 03:18 PM
Hello everyone,
I have a Cisco 1841 router with Adv Sec package on it and need to set up a static IPSec tunnel to a Cisco 3030 concentrator. The trick is that the interesting traffic has to be NAT'd through a different IP than the interface IP.
So the peering must happen on x.x.x.34, but encrypted traffic from me must come from x.x.x.35. This is a requirement of the office that I am connecting to. I've set up tunnels before, but never with this type of requirement.
What is the best way to accomplish this?
Solved! Go to Solution.
10-07-2007 10:14 AM
Hi Sean
local network at 1841 end: 192.168.5.0/24
remote network at 3030 end: 172.16.5.0/24
on 1841
int loopback10
ip address x.x.x.35
access-list 101 permit ip 192.168.5.0 0.0.0.255 172.16.5.0 0.0.0.255
ip nat inside source list 101 interface loopback10 overload
Obviously in your crypto map access-list you need to use the Natted address ie.
access-list 102 permit ip host x.x.x.35 172.16.5.0 0.0.0.255
HTH
Jon
10-07-2007 10:14 AM
Hi Sean
local network at 1841 end: 192.168.5.0/24
remote network at 3030 end: 172.16.5.0/24
on 1841
int loopback10
ip address x.x.x.35
access-list 101 permit ip 192.168.5.0 0.0.0.255 172.16.5.0 0.0.0.255
ip nat inside source list 101 interface loopback10 overload
Obviously in your crypto map access-list you need to use the Natted address ie.
access-list 102 permit ip host x.x.x.35 172.16.5.0 0.0.0.255
HTH
Jon
10-08-2007 08:38 AM
Jon, thanks very much for your post! The problem I run into (I tried creating a virtual interface before) is that the two interfaces are now on the same subnet, which the router doesn't like.
So Fast0/0 is xx.xx.xx.34 and Loopback10 is xx.xx.xx.35. Which clearly won't work. And I can't define a sub-interface on FE0/0 that isn't ISL or similar trunking.
Is there a way to get around the IP address conflict?
10-08-2007 10:03 AM
Hi
router(config)# ip nat pool NATPOOL prefix-length 32
router(config-ipnat-pool)# address x.x.x.35 x.x.x.35
ip nat inside source list 101 pool NATPOOL
HTH
Jon
10-09-2007 08:58 AM
Jon, thank you very much for your help. The tunnel is up and talking, I really appreciate your assistance.
-Sean
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide