IPSec both site-to-site and stretched LAN

[TomS]

Hi there,

I have a pfSense box which runs a IPSec tunnel to another office. There, as Sophos UTM acts as the remote tunnel endpoint.
Traffic between the subnets on both sides of the tunnel is working fine.

Now, I would like to have a "stretched subnet" 192.168.20.0/20 with PCs on both sides of the tunnel. The tunnel should be transparent, i. e. the whole subnet should behave as if it were fully local.
(I need this for some tests. I would like to know how clients in this subnet behave without having to visit the other office each time.)

Any ideas?

Best TomS