Hello List!
I'm a little new in the world of iptables and could need some advice concerning a simple Port Forwarding. I created s basic rule set as described in common howtos and the internet:
# iptables -A FORWARD -i eth0 -p tcp --dport port -j ACCEPT # iptables -t nat -A PREROUTING -i eth0 -p tcp --dport port -j DNAT --to local_ip:port
My FORWARD CHAIN contains two further entries (they actually don't affect the above rules):
# iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT # iptables -A FORWARD -i eth0 -o eth1 -m state --state ESTABLISHED,RELATED -j ACCEPT
Assuming port forwarding is turned on . . . for reference, here are rules for forwarding incoming SMTP which work for me. They look a lot like yours.
# PREROUTING
$IPTABLES -t nat -A PREROUTING -p tcp -i $EXT_IF -d $SMTP_IP --dport 25 -j DNAT --to-destination $DMZ_SMTP_IP
#FORWARD # Let already established forwarded conversations continue. $IPTABLES -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A FORWARD -i $EXT_IF -o $DMZ_IF -p tcp -d $DMZ_SMTP_IP --dport 25:25 -j ACCEPT
