Question

Opening ports on my server

Posted October 3, 2014 115.8k views

Hi

I have tried to follow this guide here (How To Set Up a Firewall Using IPTables on Ubuntu 14.04) and have done everything this tutorial said. But still when I scan my server with nmap <myserverip> i still only get port 22 and port 80 as open. I need to open port 50010 for a service I am trying to create, but I see no way for me to open this port.

sudo iptables -L:
Chain INPUT (policy ACCEPT)
target prot opt source destination

ACCEPT all – anywhere anywhere

ACCEPT all – anywhere anywhere ctstate RELATED,ESTABLISHED
ACCEPT tcp – anywhere anywhere tcp dpt:ssh
ACCEPT tcp – anywhere anywhere tcp dpt:http
ACCEPT tcp – anywhere anywhere tcp dpt:50010

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

Answers will be greately appreciated!

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4 answers
vvassi1 February 21, 2017

So for those of you still having a problem, the answer is simple. Apache needs a rule to allow traffic through the port. First find your port lsof -i :5000 (5000 is the port in question).

This will give you
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
app 2850 root 3u IPv4 22462 0t0 TCP *:5000 (LISTEN)

As you can see we are listening to 5000 with TCP connection. Now just add the rule to apache:
sudo ufw allow 5000/tcp. This will tell the firewall (ufw) to let traffic through. Now you should be okay to use the http://<yourport>:5000/path/to/service. Good Luck.

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kamaln7 October 4, 2014

The port won’t be considered “open” until something is listening on it. Your firewall config looks right so just install the service and run it and you should be good to go. You might have to configure it to listen on 0.0.0.0 instead of 127.0.0.1 or localhost, but that depends on the service’s defaults.

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Woet October 3, 2014

Ports are open by default.

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alexdo September 28, 2020

Hello, all

You can use UFW in order to do that.

UFW, or Uncomplicated Firewall, is an interface to iptables that is geared towards simplifying the process of configuring a firewall. While iptables is a solid and flexible tool, it can be difficult for beginners to learn how to use it to properly configure a firewall. If you’re looking to get started securing your network and are not sure which tool to use, UFW may be the right choice for you.

Ff your service is listening on port 50010, you can use this command to allow connections on that port:

sudo ufw allow 50010

You can check the tutorial for Ubunut 18.04 here:

https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-with-ufw-on-ubuntu-18-04

Hope that this helps!
Regards,
Alex

How To Set Up a Firewall with UFW on Ubuntu 18.04
by Brian Boucheron
This tutorial will show you how to set up a firewall with UFW on Ubuntu 18.04.
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