[CentOS] iptables: forwarding on internal device

Fri Feb 6 18:13:32 UTC 2009
Marcus Moeller <mm at gcug.de>

Good Evening,

I am trying to forward packages on an internal device using iptables:

/sbin/iptables -A FORWARD -i eth0 -o eth0 -m state --state
NEW,RELATED,ESTABLISHED -j ACCEPT

but the packages are still blocked, e.g.:

Feb  6 20:58:28 firewall kernel: DROP-TCP IN=eth0 OUT=eth0
SRC=192.168.100.177 DST=172.28.2.184 LEN=40 TOS=0x00 PREC=0x00 TTL=127
ID=16609 PROTO=TCP SPT=7166 DPT=3590 WINDOW=0 RES=0x00 ACK RST URGP=0

net.ipv4.ip_forward = 1

is set, too.

Best Regards
Marcus