Problem Setting Up Local SSH Server

Question

I am trying to setup one of my linux computers as an ssh server but I can't connect to it.

I have openssh-server and openssh-client installed already on both computers (client and server).

If I run sudo service ssh start, I get start: Job is already running: ssh, so ssh is indeed running. Also, ps aux | grep -i ssh returns

1000 2270 0.0 0.0 4080 24 ? Ss 06:04 0:00 /usr/bin/ssh-agent /usr/bin/dbus-launch --exit-with-session mate-session

1000 2286 0.0 0.3 59104 7832 ? Sl 06:04 0:00 /usr/bin/mate-keyring-daemon --start --components=ssh

1000 6333 0.0 0.0 6684 1132 ? Ss 07:29 0:00 /usr/sbin/sshd

root 12622 0.0 0.1 6684 2432 ? Ss 08:09 0:00 /usr/sbin/sshd -D

1000 13978 0.0 0.0 4392 844 pts/0 S+ 08:33 0:00 grep --color=auto -i ssh

If I run ssh localhost on the server, I can connect. But if I try that with the other computer on the lan, it doesn't work.

I have samba shares setup and working, so I don't think its a firewall problem.

Any help would be appreciated.

Answer 1

Check if ssh is listening at port 0.0.0.0:22/TCP

$ sudo netstat -putan | grep LIST | grep 22
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      4330/sshd       
tcp6       0      0 :::22                   :::*                    LISTEN      4330/sshd       

If it is listening, check if you have a firewall:

sudo iptables -L INPUT -n -v

If appears lots of lines, you could have UFW enabled check it using: sudo ufw status

If it is enabled try to add a rule to permit ssh:

 sudo ufw allow ssh

After that try to connect to ssh again. If it doesn't work you can disable the firewall completly with the next line and try again: sudo iptables -F

(note the above line is not permanent, so if you reboot the computer the firewall could start again, disable or configure your firewall correctly)