firewalling / netfilter / iptables / tcpdump on the vpn

[xavier]

Hi !

I tried tinc, i'm very happy with it  ;
however, i have difficulties firewalling on the vpn itself ;
here is my situation and what i'm experiencing:



hosta ----|
         vpn server
hostb ----|


my interface is named vpn1

i can firewall connexions starting from host a and b  to the vpn server (on the vpn server) 
(iptables -A INPUT -i vpn1 bla bla)

i can firewall connexions starting from host a to host b (on host a and b)

i can NOT firewall  connexions starting from host a to host on the vpn server.


actually, tcpdump report the same thing :

i can't see the traffic between host a and b,
even if technically it's going through the vpn server (i can see the
encrypted traffic on eth0 of the vpn server)

it's a problem when you want to rescrict access from the vpn server, between 2 vpn hosts.



any solution ?

i guess  i could create an interface for each   host (vpnhosta, vpnhostb...) but 
this would be a pain to manage.

thanks

-- 
xavier