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New Member

Problem with access subnet from router via ipsec tunnel site-to-site


I would like to please you to help with resoulve I hope simple problem :-)

between 2 routers ( Cisco 1812 with 12.4 ) I made a ipsec tunnel trough Internet.

This tunnel works well. So, UI have a problem with acces from one router to network on other side of tunnel.

it's lokk like this


When I try to ping from router1 host in subnet2 I give timeout. When I use ping with source option it works.

This is big problem form me because I have to set on router1 internal DNS which are inside of subnet2 but I can't reach them from router.

So please tell me how I can set default source IP for router to use when connection is made by tunnel?

Additional information,

When I try to ping from host in subnet2 to router1 ( internal interface ) - it works !!

The problems are only when connections are initate from router...

my configuration is similar like this one:

ip source-route


ip cef


no ipv6 cef

multilink bundle-name authenticated


crypto isakmp policy 10

encr 3des

hash md5

authentication pre-share

group 2

lifetime 28800

crypto isakmp key xxxxxxxxx address xx.xx.xx.xx no-xauth

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


crypto map SDM_CMAP_1 1 ipsec-isakmp

description Tunnel toxxx

set peer xx.xx.xx.xx

set transform-set ESP-3DES-SHA

match address 100




interface FastEthernet0

description $ETH-WAN$

ip address <internet ip>

ip nat outside

ip virtual-reassembly

duplex auto

speed auto

crypto map SDM_CMAP_1


interface FastEthernet6

interface Vlan1


ip address <internal IP> <subnet>

ip nat inside

ip virtual-reassembly

ip tcp adjust-mss 1452

no ip mroute-cache


ip forward-protocol nd

ip route <internet gw>

ip http server

ip http access-class 23

ip http authentication local

ip http secure-server

ip http timeout-policy idle 60 life 86400 requests 10000


ip nat inside source route-map SDM_RMAP_1 interface FastEthernet0 overload


ip access-list extended toInternet

remark dostep do internetu

remark SDM_ACL Category=2

remark IPSec Rule

deny ip <subnet2> <subnet1>

permit ip <subnet2> any


access-list 23 permit any

access-list 100 remark SDM_ACL Category=4

access-list 100 remark IPSec Rule

access-list 100 permit ip <subnet2> <subnet1>

no cdp run

thanks for help



Re: Problem with access subnet from router via ipsec tunnel site

When you ping, it leaves the outside interface, so your trying to ping a private address on the internet, which of course will never work. From a wokstation in Site A can you access all resources in Site B? Add host entries if you need to rely on names.

New Member

Re: Problem with access subnet from router via ipsec tunnel site

of course, the tunnel works well.

all workstations from one side of tunnel can reach computers from second side of tunnel.

The problem is only when I try reach servers in Site B from router Side A.

As I wrote, I have internal DNS, WINS etc... in Site A. Router in Site B should use them to resolve names for workstation in Site B.

Of course when I use on workstations from Site B DNS and Wins from Site A all works well, too.

What do you mean:

Add host entries if you need to rely on names.