I run Ubuntu 12.04 and have no success connecting with SSH from "Internet". The router is a TL-MR3420 which is set up to forward requests to one of the NIC's on ubuntu machine (which has in total 3 NICs).
I can SSH from a client on the "local" network/LAN.
The forward mechanism in the router seems to work. If I stop SSH service on the Ubuntu machine and instead start one on the windows machine - it works like a charm.
I do not use the Std port 22 but that shouldn't be an issue as far as I understand - sine it works on the same port on the win machine.
Since my public IS isn't static I use a dynDNS service but as said earlier the same setup works from the win machine.
The router is located on 192.168.0.1
The Ubuntu NICs has the following IP: eth2 192.168.0.100 , eth1 192.168.0.101 , eth0 192.168.0.102 and I have forwarded the "outside" request to 192.168.0.100
In regards for firewall settings on the Ubuntu machine I have disabled the ufw and the command ufw status give status: inactive.
I don't now it this is relevant information but
teh command iptables --list give:
Chain INPUT (policy ACCEPT) target prot opt source destination
Chain FORWARD (policy ACCEPT) target prot opt source destination
Chain OUTPUT (policy ACCEPT) target prot opt source destination
I have tried to catch traffic with help of wireshark (a tool I'm not too used to use) and it seems as a few (3?) "requests" actually reaches the NIC but ... nothing happens.
The syslog does not show any entries during these attempts.
Perhaps it could be some routing issues but I have reached my level of competence and are stuck ... all help and support to get this sorted out is much appreciated.
I'm new to Linux so please do not assume I have a configuration that is correct - but as I wrote earlier - if the client that initiate SSH is on the LAN it all works.
PS:I have also tried to get VPN (PPP) working from Internet with no success - once again VPN works on the windows machine ... so my best guess is that this is related to how the ubuntu machine handles (IP) traffic and not the TL-MR3420 router or other network issues.