‘telnet’ is not recognized as an internal or external command, operable program or batch file.

In this article, I will explain

How to enable telnet client feature on Windows Server?


Scenario

When I tried to check the connectivity from SharePoint Server to Exchange server on port 25 via telnet command, I got the below error.

‘telnet’ is not recognized as an internal or external command, operable program or batch file.

'telnet' is not recognized as an internal or external command, operable program or batch file.

Cause

The Telnet Client feature was not installed on the server.


Solution

What’s the Telnet?

before we go through the solution, please Let me first define what’s the telnet?

The telnet stands for “Telecommunication network“, it’s a network protocol that used to access a remote computer over the TCP/IP network or over the internet.

As administrators, we mostly use Telnet to check the connectivity between two servers within the same network, we specifically check the port status (Opened or closed) on the destination server. if it’s opened, the source server can connect to the destination server.

Install Telnet Client feature on Windows Server

To install Telnet Client feature, you should follow the below steps:

  • Open Server Manager > Manage > Add Roles and Features.

Add role and feature in Windows Server

  •  Continue clicking on Next button until reaching to Features section.

'telnet' is not recognized as an internal or external command, operable program or batch file.

  • Scroll down to finding Telnet Client > Check it.

'telnet' is not recognized as an internal or external command,

  • Click Next > Click Install.

'telnet' is not recognized

  • Wait until the feature installation has finished > Click close.

Telnet Feature installation complete

  • Go back to open the command prompt as administrator > Type the following command.

    telnet [Exchange Server FQDN or IP] [Port] Ex: telnet dc 25

  • If the port is opened, you should get the below message that means SharePoint Server can connect to the SMTP server on port 25

the port is opened using telnet cmdlet

  • Else you will get the below message that means the specified port is closed, and you could not open connection to the host.

the port is closed using telnet

In this case, you should check the below points with your Security administrator the following points:

  • What’s the IP or FQDN for SMTP Server?
  • What’s the assigned port for SMTP server? (the default port is 25).
  • On your server, the ports might be closed by a firewall. thence, you should redefine the inbound and outbound rules related to SMTP.

Applies To
  • Windows Server 2016.
  • Windows Server 2012.
  • Windows Server 2008.
Conclusion

In this article, I have explained how to enable the telnet client feature on Windows Server.

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