IP forwarding /NAT doesn't work after system update

yzhong · 10-22-2009, 07:13 PM

System is redhat 5.x
I used the following 2 rules in iptables to forwarding some packages

iptables -t nat -A PREROUTING -p tcp --dport 8000 -j DNAT --to-destination 192.168.0.244:8000

iptables -t nat -A POSTROUTING -p tcp --dport 8000 -j MASQUERADE

It works perfectly before, the kernel was 2.6.18-92.1.22.el5.

After we did a update, the kernel now is 2.6.18-128.7.1.el5.
and the forwarding is stop.

I just wondering where can I get some debug information. I checked /var/log/message, dmesg ... seems nothing there.

Could anyone give me some clue, thanks in advance.

mail4vijay · 10-23-2009, 11:55 AM

Quote:

Originally Posted by yzhong

System is redhat 5.x
I used the following 2 rules in iptables to forwarding some packages

iptables -t nat -A PREROUTING -p tcp --dport 8000 -j DNAT --to-destination 192.168.0.244:8000

iptables -t nat -A POSTROUTING -p tcp --dport 8000 -j MASQUERADE

It works perfectly before, the kernel was 2.6.18-92.1.22.el5.

After we did a update, the kernel now is 2.6.18-128.7.1.el5.
and the forwarding is stop.

I just wondering where can I get some debug information. I checked /var/log/message, dmesg ... seems nothing there.

Could anyone give me some clue, thanks in advance.

Did you check ip forwarding settings in /etc/sysctl.conf , it should set to...

ipforward=1 , if not change it to 1... and reboot the box.