[CentOS] iptables: forwarding on internal device

Good Morning,

iptables -L -v now shows:

    0     0 ACCEPT     all  --  eth0   eth0    anywhere
anywhere            state NEW,RELATED,ESTABLISHED

But the packages are still dropped:

Feb  9 10:48:20 firewall kernel: DROP-TCP IN=eth0 OUT=eth0
SRC=192.168.100.192 DST=172.28.2.161 LEN=44 TOS=0x00 PREC=0x00 TTL=59
ID=54 PROTO=TCP SPT=9100 DPT=4068 WINDOW=0 RES=0x00 ACK SYN URGP=0

Could it be that I have to enable something in proc to allow
forwarding on an internal device?

Best Regards
Marcus