I'm pretty stumped with this, I've been messing around with it for hours with no joy - I know it'll be something stupid I've missed.
At our old office we have a Netgear DG834PN router which has several port forwards set-up - several to a Server 2003 machine running there and a few to a backup NAS machine.
All of this was working fine until the other week. I did install DHCP server on Server 2003 but I've since unauthorised/stopped that so it shouldn't be doing anything any more. Everything has been rebooted since.
Port forwards work fine to the office server but fail to other machines. I've even tried redirecting port 80 from Server 2003 (which works fine) to another machine (which has port 80 open) and it still fails - I've confirmed this by trying to connect from several outside locations.
From within the network or via remote desktop to the server I can access everything, if I VPN into the server I can access everything (both bypassing NAT I presume).
SSHing into the router or looking at its logs in the web admin everything looks ok, it's going to the right IP, the right port, and the clients shouldn't be blocking the connection (they weren't before, and neither can I see anything in their logs) but the connection never happens. I've tried testing with web browsers, FileZilla and telnet.
Here's a log from the router when I try to connect to a working port forward rule to Server 2003 (HTTP) and a non-working port forward rule to the backup NAS (FTP, running on port 2121 - but the ports/protocols seem irrelevant):
// server 2003, works Sun, 2011-05-15 00:22:04 - TCP Packet - Source:88.110.x.x,32444 Destination:192.168.0.7,80 - [HTTP match] // NAS machine, fails (2121 is the correct port) Sun, 2011-05-15 00:21:41 - TCP Packet - Source:88.110.x.x,32443 Destination:192.168.0.90,2121 - [FTP_NAS match]
Here's the entries in iptables from the router (they were configured with the web UI) for port 2121 (I've substituted our real domain name with example.co.uk):
# iptables --list | grep :2121 LOG tcp -- anywhere anywhere state NEW tcp dpt:2121 LOG level warning prefix `[FTP_NAS match]' ACCEPT tcp -- anywhere nas.ads1.example.co.uktcp dpt:2121
Does any one have any more ideas? Thanks in advance!