topic Re: cannot telnet to any port in Operating System - Linux

cannot telnet to any port

Oscar Garcia — Tue, 07 Nov 2006 12:20:13 GMT

Hi Guys,

Well not exactly I can telnet normally (port 23) but that's it.
We are trying to setup a web application server using ports 7784 and 9001 in a Suse SLES 8. But we are not going anywhere.
I am trying to telnet to the machine thru the port but this is what I get:
$ telnet 192.168.1.14 7784
Connecting To 192.168.1.14...Could not open connection to the host, on port 7784: Connect failed
I build the server some days ago, and I am quite newbie in the linux side. I am not running a firewall or any other fancy thing (not that I am aware of).

Thanks for all you help in advanced.

Re: cannot telnet to any port

Ivan Ferreira — Tue, 07 Nov 2006 12:55:22 GMT

The first thing that you should do is to identify if the ports are LISTENING for connections, use netstat -an for that, for example:

netstat -an | grep 7784

You should see a line like this:

Proto Recv-Q Send-Q Local Address Foreign Address (state)
tcp 0 0 *.7784 *.* LISTEN

This indicates that the port is open and waiting for connections. If you don't see a line like that, then your application or web service is not started or cannot start because of an error.

Re-check that your firewall is not preventing connections, check the status with:

iptables -nL

Re: cannot telnet to any port

Alexander Chuzhoy — Tue, 07 Nov 2006 12:56:30 GMT

apparently the service didn't come up properly.
You can check for opent ports with netstat utility.
read man unless you're already familiar with it.

Re: cannot telnet to any port

Oscar Garcia — Wed, 08 Nov 2006 11:50:30 GMT

Thank you for your replies Ivan & Alexander.
Linux is not my cup of tea, and I just hate to spend hours and hours reading about the 100 different ways of doing one thing.
I did not know that the application is the one that opens the ports. I thought the ports were always open, available and listening... but there is always something new to learn every day.
Today I came and after reading your answers I gave it a go and I managed to connect.
The DBA told me he had reinstalled some software and now the problem was shifted on to how to reconfigure the kernel parameters.
I do not want to hurt any feelings but I think the linux and the Suse documentation stinks!!!
Thanks again for your help!

Re: cannot telnet to any port

Oscar Garcia — Wed, 08 Nov 2006 11:52:23 GMT

It seems that the application did not start up and therefore ports were not open. Once rectified this, I managed to connect thru port 7784.