Site to site VPN IPSec tunnel with two 880 routers

[pcfreak49]

I want a site to site vpn ipsec tunnel there wants to use two Cisco 880 routers that are connected to a modem / router is this possible?

[Jeff Van Houten]

A modem? Like an asynchronous modem? Why would you want to encrypt over a modem connection?

Sent from Cisco Technical Support iPad App

[pcfreak49]

yes I want between the two routers do but encrypt the router with cable modem / router with 1 public ip address how can I configure

[olpeleri]

You do get a public IP address on one of the boxes right? Or both routers are behind a NAT box?

If there is a NAT box then you need to configure a static NAT [ on that device] for udp 500 and udp 4500 towards the router.

When it's done then you can configure a tunnel protection tunnel interface

[pcfreak49]

the modem / router has 1 public ip address Get the routers ip address in a private ip range 192.168.0.1

[olpeleri]

So you will have to configure static NAT on theses modem's. Is it something possible?

[pcfreak49]

the modem / router that nat public ip address hide the ip addresses 192.168.0.1 I can not configure nat

[olpeleri]

Well to build a VPN between both sides, then you need at minimum a site either without NAT/PAT or with Static NAT [ udp 500 and 4500]

If both are behind pat, then you can't build a vpn since the udp traffic will be dropped without any xlate....

[pcfreak49]

how can I configure the routers because they have a private ip address

[olpeleri]

They are both on different sites right? Then you can't with static NAT for udp 500 / 4500

[pcfreak49]

R1 is private ip address 192.168.0.121 and R2 is private ip address 192.168.0.122 percies what should I configure the routers?

[olpeleri]

U did not answer my initial question. Are theses 2 devices behind the SAME Cable Modem or behind DIFFERENT Cable Modem?

Let me know....

[pcfreak49]

yes the routers are behind the same cable modem