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Configuring an IPSec Tunnel Between Router and PIX w/Duplicate LAN Subnets

UNIKAPERUGIA
Beginner
Beginner

As in title,

I need to make a site to site vpn between an pix and a router with duplicated subnets.

Pix as inside have a 192.168.144.0/24 and he manages already 2 site-to-site vpn, one with another pix (that have inside 10.10.9.0/24) and the second one with another pix (that have inside 10.10.12.0/24). Now i need to add another one vpn site to site with cisco ios (that have "inside" 10.10.9.0/24).

Any sugestion, egsample or link?

Thanks

3 REPLIES 3

mheusinger
Advocate
Advocate

Hello,

what you need to do is to perform NAT before the IPSec tunnel and translate the second 10.10.9.0/24 to some other network not yet used on the PIX, f.e. 10.10.99.0/24. The NAT configuration on the router would look like this:

crypto isakmp policy 10

hash md5

authentication pre-share

group 2

lifetime 300

!

crypto isakmp key MyKey address 2.2.2.2

!

crypto ipsec transform-set myset esp-des esp-md5-hmac

!

crypto map mymap local-address Serial0/0

crypto map mymap 10 ipsec-isakmp

set peer 2.2.2.2

set security-association lifetime seconds 180

set transform-set myset

match address 110

!

!

interface Ethernet0/0

ip address 10.10.9.1 255.255.255.0

ip nat inside

!

interface Serial0/0

ip address 1.1.1.1 255.255.255.252

crypto map mymap

ip nat outside

!

ip nat pool NATforTunnel 10.10.99.1 10.10.99.254 netmask 255.255.255.0

ip nat inside source list 110 pool NATforTunnel

!

access-list 110 remark NAT-list

access-list 110 permit ip 10.10.99.0 0.0.0.255 192.168.144.0 0.0.0.255

Extend the ACL 110 to your needs and adjust the IPSec stuff and IP addresses to your environment.

Hope this helps! Please rate all posts.

Regards, Martin

Perfect, can you make me an eesample on the pix side?

Thanks ;)

mheusinger

Thanks for this post, quick question, this example is to configure the router on my location, NOT the remote location right?

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