[LARTC] VPN question

[Ron Brinker <service@xxxxxxxxx>]

I have a GRE VPN set up and partially (I think) working. I have two linux 
systems connecting two separate subnets to the internet. I have a VPN set 
up between the two of them. I can ping their respective internal IP 
addresses (we'll call them 192.168.1.1 and 192.168.2.1 for the sake of 
argument) just fine. I also have two Windows workstations on the internal 
networks (we'll call them 192.168.1.100 and 192.168.2.100).

Should it be possible for me to ping 192.168.1.100 from 192.168.2.100 and 
vice-versa?

I can ping 192.168.1.1 from 192.168.2.1 and 192.168.2.100
and
I can ping 192.168.2.1 from 192.168.1.1 and 192.168.1.100
but
I can't ping 192.168.1.100 from 192.168.2.100 or vice-versa.

I hope I didn't lose anybody there :)

I'm sure I'm just missing something simple. I anyone could throw some ideas 
at me, and/or point out any possible kernel options I may have failed to 
compile in, I would appreciate it.

TIA,

Ron Brinker
EMC Computers
service@xxxxxxxxx