linux - Why would a ssh connection fail to connect with whole proper setups?

Using Ubuntu Server 14.04 I got ssh server running on port 2222 (they asked it like that at building). I already got whole setups reviewed and nothing seems to be ok.

This is what's set up:

• At building they redirect tcp connections on port 2222 to my IP.


• Same goes for port 80, which I can reach.


• When I attempt to connect through SSH at port 2222, I can see the incoming network activity using iftop.



• I got ufw running with proper rules:

  
  
  
  

  2222/TCP ALLOW Anywhere




• At sshd.conf file I got:




• I got ssh server listening at port 2222.



• I set the ssh server in AUTH mode for logging but I can't see anything at /var/log/auth.log when trying to connect.


• This is my sshd.conf file.


• Yep, the ssh daemon is running and it was restarted.

So anytime I try to connect I get a message like:

ssh: connect to host  port 2222: Connection refused

Running client in verbose mode outputs:

debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Connecting to  [] port 2222.
debug1: connect to address  port 2222: Connection refused

ssh: connect to host  port 2222: Connection refused

And same will happen if I try to login from a host at same network.

Running netstat at server like sudo netstat -tulpn | grep ssh outputs:

tcp    0    0 127.0.0.1:2222    0.0.0.0:*    LISTEN    969/sshd

Running nmap against the public IP from outside the network outputs:

Host is up (0.051s latency).
Not shown: 996 filtered ports
PORT     STATE  SERVICE
21/tcp   closed ftp
80/tcp   open   http
2222/tcp closed unknown
8080/tcp closed http-proxy


Nmap done: 1 IP address (1 host up) scanned in 5.31 seconds

Trying telnet 2222

Outputs:

telnet: Unable to connect to remote host: Connection refused

Same goes if tried with network ip inside building.

But well iftop ran at server shows there's actually network activity when trying to login.

Running tcpdump at server like: tcpdump -vniay port 2222 -i eth0 will output this on login attempt:

15:53:36.812402 IP (tos 0x0, ttl 64, id 56954, offset 0, flags [DF], proto TCP (6), length 60)
  192.168.1.86.39822 > 192.168.1.90.2222: Flags [S], cksum 0xa1b8 (correct), seq 3966921350, win 292000, options [mss 1460,sackOK,TS val 308476 ecr 0,nop,wscale 7], lenght 0

What could it be failing?

Answer

Based on that netstat output, and your sshd configuration file (especially this line) your SSH daemon is listening on a local-only IP address (127.0.0.1), and not an IP that actually communicates with your LAN or outbound via the router/gateway device on the network.

Verify that your sshd_config is set to have a ListenAddress line that is on your LAN, such as the private LAN IP address assigned to the server. If you don't have one, add it after the port directive, with syntax such as ListenAddress 0.0.0.0 or ListenAddress ::, replacing those items with actual IPv4 or IPv6 addresses.

And remember that binding to any IP address in 127.0.0.0/8 will only end up at the local computer itself, not any address that can actually route to your LAN / local network / anywhere else.