Call: (480) 382-8464

Network Troubleshooting With Telnet

Using Telnet to Test Open Ports

The Setup on Digitalcrunch.com:

  • 5555 is blocked via a firewall
  • 80 is open and running http service
  • 22 is open and running ssh

How to Manually Use Telnet

Typing anything and then hitting enter is like sending protocol information to the remote service. If you know the protocol and it accepts ascii, you can manually interact. If not, it will give you an error message. You can’t type binary data this way though.


Example of Telnet Error Message

	C:\>telnet digitalcrunch.com 22

telnet protocol mismatch


Example of Manually Typing ASCII protocol

	C:\>telnet digitalcrunch.com 80
	GET /index.php HTTP/1.1 
	host: digitalcrunch.com
	<enter>

testing http with telnet


Example of Blocked Port:

	C:\>telnet digitalcrunch.com 5555

telnet connect failed


No Service exists on server:

For example, the database team wants to test if they can get to digitalcrunch.com on port 8888, however, the server isn’t provisioned yet – but they still want you to test! In this example, I have opened the firewall to port 8888, but there is nothing listening on that port. Compare to the “blocked port” above to see the difference.

    C:\>telnet digitalcrunch 8888
    Connecting To digitalcrunch.com...Could not open connection to the host, on port 8888: Connect failed

Leave a Reply

Your email address will not be published. Required fields are marked *

Main Offers/Services

Hosting and website related services offered by Digital Crunch:



Managed VPS Hosting

Server Updates, Module/Software Installs, Firewall, Security, Hosting Management, Wordpress - let us manage it for you

Hosted Email

Setup and Maintain Business Class, Secure Email Hosting including spam protection and 25GB of storage space

Linux Consulting

Server Updates, Module/Software Installs, Firewall, Security, Hosting, Wordpress and Apps, anything related to Linux

Email Marketing Services

We broadcast your content to your list, capture leads for you, follow up on schedules, make more sales for you

Website Maintenance

Content updates, menu changes, graphics changes, adding content, getting links, building traffic, building sales funnels

Hosting Tutorials

Tutorials we've written for other customers that like to get their hands dirty and learn about hosting