IPSEC site to site vpn with NAT on one of the tunnel endpoints

From: operator sid (ccie1@live.co.uk)
Date: Thu Feb 19 2009 - 19:26:46 ARST


Hi All

I am having problems with L2L ipsec VPN, as the tunnel is not initiating at
all... I have ASA on the A-end and PIX on B-end. The ASA on the A-end is also
doing NAT of both source and destination and it is also tunnel endpoint.

the topology is like this. Note the LAN addresses specified are not directly
connected but behind the ASA and PIX

  (10.1.1.0/24) ----- --A-end - (ASA)--------------------------- INTERNET
-------------------- B-end PIX ---- (10.20.20.0/24)

NAT ON ASA -
10.1.1.1/32 (server) NAT'ed TO 80.2.2.2/32 - SO B-end see's this server as
80.2.2.2 address
10.2.2.0/24 NAT TO 10.20.20.0/24 - So A-end see's B-end subnet as
10.2.2.0/24

The problem is that the tunnel is not even initiating... i have attached
config...

A-end ASA

ASA Version 7.2(3)

interface GigabitEthernet0/1
 nameif inside
 security-level 100
 ip address 90.1.1.1 255.255.255.128 standby 90.1.1.2
!
interface GigabitEthernet0/2
 nameif outside
 security-level 0
 ip address 80.1.1.1 255.255.255.128 standby 80.1.1.2

access-list proxy_acl extended permit ip host 80.2.2.2 10.20.10.32 10.20.20.0
255.255.255.0
access-list proxy_acl extended permit ip 10.20.20.0 255.255.255.0 80.2.2.2
255.255.255.255

access-list outside extended permit icmp any any
access-list outside extended permit esp any any
access-list outside extended permit udp any any eq isakmp
access-list inside extended permit ip any any

access-list policy-nat-1 extended permit ip 10.0.0.0 255.0.0.0 any
access-list policy-nat-1 extended permit ip 172.16.0.0 255.240.0.0 any

global (outside) 1 100.1.1.1
nat (inside) 1 access-list policy-nat-1

static (inside,outside) 80.2.2.2 10.1.1.1 netmask 255.255.255.255
static (outside,inside) 10.2.2.0 10.20.20.0 netmask 255.255.255.0

access-group inside in interface inside
access-group outside in interface outside

route inside 172.16.0.0 255.240.0.0 90.1.1.5
route inside 10.0.0.0 255.0.0.0 90.1.1.5
route outside 0.0.0.0 0.0.0.0 80.1.1.5

crypto ipsec transform-set ESP-3DES-SHA esp-3des esp-sha-hmac

crypto map CRY-MAP 10 match address proxy_acl
crypto map CRY-MAP 10 set peer 60.1.1.1
crypto map CRY-MAP 10 set transform-set ESP-3DES-SHA
crypto map CRY-MAP 10 set security-association lifetime seconds 28800
crypto map CRY-MAP interface outside
crypto isakmp enable outside

crypto isakmp policy 5
 authentication pre-share
 encryption 3des
 hash sha
 group 1
 lifetime 86400
!
tunnel-group 60.1.1.1 type ipsec-l2l
tunnel-group 60.1.1.1 ipsec-attributes
 pre-shared-key *

B-end PIX

access-list proxy-acl permit ip 10.20.20.0 255.255.255.0 8.2.2.2
255.255.255.255
access-list no_nat permit ip 10.20.20.0 255.255.255.0 8.2.2.2 255.255.255.255

nat (data) 0 access-list no_nat

crypto ipsec transform-set 3dessha1 esp-3des esp-sha-hmac
crypto map vpn 10 ipsec-isakmp
crypto map vpn 10 match address proxy-acl
crypto map vpn 10 set peer 80.1.1.1
crypto map vpn 10 set transform-set 3dessha1
crypto map vpn interface outside

isakmp key ******** address 80.1.1.1 netmask 255.255.255.255
isakmp identity address
isakmp policy 10 authentication pre-share
isakmp policy 10 encryption 3des
isakmp policy 10 hash sha
isakmp policy 10 group 1
isakmp policy 10 lifetime 86400



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