Hello everyone, I have a extrange issue with a conntrack entry. There is a nat server configure in this way DMZ 194.139.30.0/23 --- 194.139.30.16 nat 192.168.12.100 ---- 192.168.12.0/24 private network The nat machine does postrouting in all traffic from the private network to DMZ, and there is no problem but in one server in the DMZ with windows 2008 server the traffic doesn't return to the origin, I can see the traffic with tcpdump like this 17:19:23.971978 IP (tos 0x0, ttl 64, id 0, offset 0, flags [DF], proto: ICMP (1), length: 84) 192.168.12.91 > 194.139.30.62: ICMP echo request, id 12075, seq 1, length 64 <----- The echo request original OK 17:19:23.972094 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto: ICMP (1), length: 84) 194.139.30.16 > 194.139.30.62: ICMP echo request, id 12075, seq 1, length 64 <------ Masquerade the source IP OK 17:19:23.972164 IP (tos 0x0, ttl 128, id 25050, offset 0, flags [none], proto: ICMP (1), length: 84) 194.139.30.62 > 194.139.30.16: ICMP echo reply, id 12075, seq 1, length 64 <------- The echo reply OK ¿?¿?¿? <----------- Lost echo reply not OK There isn't the packet from 194.139.30.16 to 192.168.12.91 despite off the conntrack table show cat /proc/net/ip_conntrack | grep '30.62' icmp 1 29 src=192.168.12.91 dst=194.139.30.62 type=8 code=0 id=12075 packets=11 bytes=924 [UNREPLIED] src=194.139.30.62 dst=194.139.30.16 type=0 code=0 id=12075 packets=0 bytes=0 mark=0 use=1 The packet in tcpdump match on the conntrack entry. "id 12075" in both cases, but if I LOG the traffic with the LOG iptables target I see the reply in INPUT table not in the FORWARD. Thank you and sorry for me bad english. -- To unsubscribe from this list: send the line "unsubscribe netfilter" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html