Hi, On Mon, Nov 23, 2009 at 4:15 PM, Giovanni Tirloni <tirloni at gmail.com> wrote: > On Mon, Nov 23, 2009 at 12:10 PM, Peter Peltonen > <peter.peltonen at gmail.com> wrote: >> Hi, >> >> I am unable to get my LAN masqueraded using SNAT with CentOS 5.3 and iptables. >> >> I have the following setup: >> >> eth0: connects to internet with static public IP 1.2.3.1 (obscured >> here for privacy) >> eth1: connects to DMZ with static public IP 1.2.3.2 (obscured here for privacy) >> eth2: connects to LAN with static private IP 192.168.0.1 >> >> Traffic to hosts in the DMZ/Internet through eth0/1 work fine. >> >> I tried masqueradig the LAN with following: >> >> ptables -A FORWARD -i eth2 -j ACCEPT >> iptables -A FORWARD -o eth2 -j ACCEPT >> iptables -A POSTROUTING -t nat -s 192.168.0.0/24 -o eth0 -j SNAT >> --to-source 1.2.3.1 >> >> After this I can ssh to a server in the Internet from the LAN using >> the server's IP address but not its name. The w command on the server >> tells me that my address has not been masqueraded (its 192.168.0.2, >> the LAN client's private IP). > > If you can ssh to a server on the Internet then your connectivity is > working. You might want to check if DNS is allowed and working from > the LAN hosts to the Internet. > > The fact that 'w' shows your internal IP address is because you're > connecting from the LAN to the gateway, which doesn't trigger the SNAT > because it's not forwarding any packets... only accepting your > connection. Hmm,I am SSHing not to the gateway but to a server in the Internet, so shouldn't it masquerade the address and w show the gateway's IP and not the client's -- isn't this the whole point of the SNAT? No other service than SSH seems to work. If I do "telnet mydnsip 53" there is no response, it just hangs. I also have correct DNS in /etc/resolv.conf. Best, Peter