zdraveite imam sledniq vapros:
 imam ma6ina s debian linux na koqto ima 3 lan katri s ip
-ta
 192.168.100.1, 192.168.102.1, 192.168.200.1. Default gw e na
mreja 192.168.200.0. kam ip 192.168.100.1 se varzva lan
 a kam ostanalite 2 mrejovi karti se vrazvat drugi 2 ma6ini
na koito se pravi nat 

62.16.90.5<<<<nat<<<<<192.168.102.2<<GW<<192.168.102.1
                  
192.168.200.2>>>192.168.200.1>>>>nat>>>86.93,14.6
                                         
192.168.100.1<<<<<LAN

 po kakav na4in moga da pusna irc i ICQ ot LAN kam ip
86.93,14.6
 a ostanalite zaqvki kam internet da prodaljat da si minavat
prez default gateway kam ip 62.16.90.5

probvai neshto podobno mozhe i da ti svurshi rabota
echo 1000 IcqIrc >> /etc/iproute2/rt_tables
ip rule add fwmark 1 table IcqIrc
 ip route add default via 192.168.200.1 dev
ethX[192.168.200.2] table IcqIrc
 iptables -t mangle -A PREROUTING -i ethY[192.168.100.1] -p
 tcp -m multiport --dport 5190,6667,194,529,994 -j MARK
--set-mark 1
 iptables -t mangle -A PREROUTING -i ethY[192.168.100.1] -p
udp -m multiport --dport 194,529,994 -j MARK --set-mark 1

mozhe da ne sum utselili adresite kakto triabva.
za poveche informatsiia: www.lartc.org, man ip