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I just installed a ubuntu server 16.04 lts, a basic server installation with ssh.

I installed services listening on ports { 443, 9900, 9901, 9997 } and they seem to be listening just fine:

$ netstat -plan --protocol=inet
(Not all processes could be identified, non-owned process info will not be shown, you would have to be root to see it all.)
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
tcp        0      0 0.0.0.0:9900            0.0.0.0:*               LISTEN      -               
tcp        0      0 0.0.0.0:9997            0.0.0.0:*               LISTEN      -               
tcp        0      0 0.0.0.0:9901            0.0.0.0:*               LISTEN      -               
tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      -               
tcp        0      0 0.0.0.0:443             0.0.0.0:*               LISTEN      -               
tcp        0      0 (serveraddress):53430     (serveraddress):9900      ESTABLISHED -               
tcp        0    388 (serveraddress):22        (myaddress):53994      ESTABLISHED -               
tcp        0      0 (serveraddress):9900      (serveraddress):53430     ESTABLISHED -          

When I attempt to connect to them from outside my box, I get connection refused.

$ nmap -p22,443,9900,9901,9997 (serveraddress)

Starting Nmap 7.01 ( https://nmap.org ) at 2017-02-01 19:12 EST
Nmap scan report for IP-(serveraddress).static.fibrenoire.ca (serveraddress)
Host is up (0.014s latency).
PORT     STATE    SERVICE
22/tcp   open     ssh
443/tcp  open     https
9900/tcp filtered iua
9901/tcp filtered unknown
9997/tcp filtered unknown

Nmap done: 1 IP address (1 host up) scanned in 1.26 seconds

I have not activated the firewall

$ sudo ufw status
Status: inactive

What is wrong? Anything special I have to do to open port # >= 1024?

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  • I suspect that the service provider hosting my server may have some sort of filtering or firewall, but I have no idea how to check for this? Is there a simple way to check for this?
    – Bamaco
    Feb 2, 2017 at 1:10
  • 1
    Yes, ask the service provider. Feb 2, 2017 at 2:35

1 Answer 1

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Turns out my server was behind a firewall controlled by my service provider. I asked him to unblock the ports I need.

Is this something normal or common?

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