I don't think my first two emails went through, either that or the list is incredibly slow today. Thus I'm trying this from a different email address. I am thoroughly confused by IPTables. I'm not totally new to Linux however I'm clearly no guru. I have an older Linux machine running IPChains that I am going to need to replace soon. This machine was set up by another person who is no longer available to me. I've been researching how to convert this IPChains setup to IPTables but I just can't seem to figure it out. This is executed from rc.local on the old machine (IP addresses altered to protect the innocent): echo "Turning on IP Forwarding" /bin/echo "1" > /proc/sys/net/ipv4/ip_forward echo "Setting IPMasq Rules" /usr/sbin/ipmasqadm mfw -A -m 3 -r 10.0.0.1 echo "PortForwarding" /usr/sbin/ipmasqadm portfw -a -P tcp -L 192.168.1.1 25 -R 10.0.0.1 25 The new machine that I'm running this on is a CentOS 4.2 x86-64 running kernel 2.6.9-22.0.1.EL. Some of the research that I've done indicates that I should have something like this going on: iptables -t nat -A PREROUTING -p tcp -i eth1 -d 192.168.1.1 --dport 25 -j DNAT --to 10.0.0.1:25 iptables -A FORWARD -p tcp -i eth0 -d 10.0.0.1 --dport 25 -j ACCEPT But that doesn't work. Then I ran across a site that added a couple of statements to the mix: echo 1 > /proc/sys/net/ipv4/ip_forward iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE The additional lines don't help my cause either and I am a bit lost here. If anyone has any helpful information I would greatly appreciate it. Thanks.
