Known bugs with the 2.4.0 kernel: 1) NAT in the OUTPUT chain does not work in general. The fix is intrusive, and means we will have a CONFIG_NF_IP_NAT_LOCAL option when it comes back. 2) tcpdump traffic is corrupted by OUTPUT NAT. 3) Connection tracking doesn't wait very long for reply FIN, meaning that half-closed pipes can time out early (seen frequently with squid).