adsl connection drops when port forwarding large files
 

Hi,

I have a home network involving a firewall and then a number of machines sitting behind this firewall. All redhat 9. I have an odd problem in that my adsl connection drops sporadically. This only happens when copying large files via scp2 from the remote machine to a machine behind the firewall. It doesn't happen however if i just copy directly onto the firewall.

It must therefore be something about the forwarding. It will do small files but large ones cause the connection to drop.

I use port 2222 to copy to the machine behind the firewall and 22 to go directly to the firewall.

I use narc as a firewall and have the forwarding

iptables -t nat -A PREROUTING -i ppp0 -p tcp -d 81.5.xxx.xxx --dport 2222 -j DNA
T --to 192.168.1.xxx:22
iptables -A FORWARD -i ppp0 -o eth1 -p tcp -d 192.168.1.xxx --dport 22 -j ACCEPT

Any help appreciated,

cheers

Do you have an ESTABLISHED/RELATED rule in FORWARD before the ACCEPT rule?
What is your DNAT/MASQUERADE rule in POSTROUTING?
do iptables-save to list active rules