After you created a Site-to-Site VPN (if you don’t know, check this post)

In this case we will use putty (click here to download it) to connect to the ASA 5510

1. Login in to the cisco asa and put it in configuration mode (command: configure terminal):

2. To see all the cryptomaps run the command “show run crypto map“. (you may see more or less depending on the amount of VPN tunnels you have.

3. Find the IP you want to change, from the example above we can see the tunnel we want to change is using “outside_map 2” so lets remove the entry for the old IP address and put one in for the new IP address. Use the command “no crypto map xxxxxxxxxxxx” to delete the tunnel and then “crypto map xxxxxxx” to create the tunnel.

4. That’s the cryptomap changed, now for the tunnel group. You can see all your tunnel groups with a “sho run tun” command.

5. To delete a tunnel group, you use the “clear config tunnel-group” command.
Note: Before you delete it, make sure you know the pre shared key / shared secret – to see this, issue a “more system:running-config” command.

6. Then simply create a new tunnel group, with the new IP address, and the same shared secret / pre shared key as the old one.

7. Finally, save the new config with a “write mem” command

Done, you changed the Remote Site IP address and the VPN should be up and running.