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Site to Site VPN with Static Nat

I need to set up a site to site vpn between 2 ASA (1 5510 and a 5505).  The 5505 internal network is also in use on the internal portion of the 5510 so I wanted to NAT the outbound traffic from Site A (5510) to Site B (5505) and vice versa.  I was thinking of doing something along these lines:

To allow the traffic to flow through the tunnel when having the same addressing scheme on both ends, you should NAT the VPN traffic.

ie.

Site A LAN 10.0.0.0/24

Site B LAN 10.0.0.0.0/24

Site A config:

access-list NATtoSiteB permit ip 10.0.0.0 255.255.255.0 172.16.40.0 255.255.255.0

static (inside,outside) 172.16.45.0 access-list NATtoSiteB

access-list crypto permit ip 172.16.45.0 255.255.255.0 172.16.40.0 255.255.255.0

Site B config:

access-list NATtoSiteA permit ip 10.0.0.0 255.255.255.0 172.16.45.0 255.255.255.0

static (inside,outside) 172.16.40.0 access-list NATtoSiteA

access-list crypto permit ip 172.16.40.0 255.255.255.0 172.16.45.0 255.255.255.0


And then I would use the "crypto" acl for building the crypto map.  Would that be the best approach?

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4 REPLIES

Site to Site VPN with Static Nat

This looks good, here is a document that you can use for reference:

http://www.cisco.com/en/US/products/ps6120/products_configuration_example09186a0080b37d0b.shtml#configs

Thanks,

Tarik Admani
*Please rate helpful posts*

Tarik Admani *Please rate helpful posts*

Site to Site VPN with Static Nat

Hi David,

Whatever you have made is correct. The concept behind this scenario is your crypto map acl should be between your NAT subnet to other site NAT subnet. Here you are making Site A nated to 172.16.45.0/24 to Site B Nated subnet 172.16.40.0/24.

Your nat cl should be from your real subnet to the NAted subnet @ the other site.

10.x.x.x to 172.16.40.0/24 - Site A

10.x.x.x to 172.16.45.0/24 - Site B

So present configuration fullfills that scenario. So it will work as it is.

Please do rate for the helpful posts.

By

Karthik

New Member

Site to Site VPN with Static Nat

  Ok great.  And to get to 10.0.0.100 in the remote site I would just use 172.16.45.100 correct?  If only 1 side needed to be nat'ed would I basically do the same, just do the nating on 1 side and have my access for the crypto map on the other site reference the nated addresses?

Site to Site VPN with Static Nat

Yes that is correct.

thanks,

Tarik Admani
*Please rate helpful posts*

Tarik Admani *Please rate helpful posts*
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