Hello ,
It is possible to setup an IPsec tunnel between two routeros with overlapping private networks ? My network setup is :

Site A
LAN 192.168.1.0/24
WAN 86.xxx.xxx.xxx/27

Site B
LAN 192.168.1.0/24
WAN 86.xxx.xxx.xxx/27

Any hint ?

http://wiki.mikrotik.com/wiki/Manual:Pa ... encryption

IPSec policies are evaluated after post-routing, so you can use src-nat to NAT the two networks against each other and make the IP space unique, and then send the NAT'd traffic via IPSec.
The 'netmap' NAT action can translate whole network ranges easily.

Big question is, what is going across the networks? If there is anything that involves dns resolution from one side to the other, you are gonna have to change the ips on one network.

Thanks for the suggestion! I managed to configure it.

Would you mind sharing your working configuration?

I have 2 RB751s using an EOIP tunnel, both networks are 192.168.100/24.

One router is 192.168.100.1, the other is .10.

I posted my rules in this post.
http://forum.mikrotik.com/viewtopic.php?f=13&t=104238