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Mayank Singh
Asked: 2015-08-09 12:29:29 +0800 CST

Port 22 is always open

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I configured a new Ubuntu Installation and set up the firewall. All incoming was denied and all outgoing was denied as well(with exception for port 8080, as I am behind a proxy). I then tried an online port scan and found that my ssh port(22) was open. I double checked but the problem remained. I specifically denied port 22 in the firewall, but the port is still shown as open(all other ports are closed). What is the reason behind this?

Output of netstat -tlpn is 

tcp        0      0 127.0.1.1:53            0.0.0.0:*               LISTEN      -               
tcp        0      0 127.0.0.1:631           0.0.0.0:*               LISTEN      -               
tcp6       0      0 ::1:631                 :::*                    LISTEN      -
networking

1 Answers

  1. Best Answer

    As the netstat -tlpn output indicates you don't have port 22 is in LISTEN state that is the port is closed.

    As for the Online scan results, this should be the results from scanning the public IP interface of your router (could be the proxy in your case).

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