KB Article | Forcepoint Support

Problem Description

In the event of troubleshooting by Forcepoint support, a telnet check may be recommended, but results in the following error:
"‘telnet’ is not recognized as an internal or external command, operable program"
Forcepoint software requires certain ports to be open in order for its services to function properly. If not properly set, connectivity issues with the SQL server or deployment errors may occur.


Forcepoint uses the ports located in the below articles for connectivity between its components. In the case of firewall changes or other events in the environment, these ports may mistakenly become blocked.
The Telnet tool on Windows servers can be used to test port connectivity.

Enabling Telnet

  • Enabling Telnet client through Command Prompt:

    1. Open Command Prompt as Administrator.

    2. Type Dism /Online /Enable-feature /FeatureName:TelnetClient
  • Enabling Telnet through Powershell.
    1. Open Powershell.
    2. Type Install-WindowsFeature -name Telnet-Client
  • Enabling Telnet as a Windows Feature.
    • Windows Server 2008:
      1. Open Server Manager.
      2. Click Features.
      3. Click Add Features.
      4. Enable Telnet Client.
      5. Click Next then click Install.
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  • Windows Server 2012-2016:
    1. Open Server Manager.
    2. Click Add roles and features.
    3. Click Next until reaching Features.
    4. Select Telnet Client.
    5. Click Next then click Install.
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  • Windows Client 7, 8, and 10:
    1. Open Control Panel.
    2. Navigate to Programs and Features.
    3. Click Turn Windows features on or off.
    4. Select Telnet Client.
    5. Click OK
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Using Telnet to test Ports

  1. Open Command Prompt. 
  2. Type telnet [domain name or IP][port]
    • Example: telnet 80
  3. Check the status of the operation. 
    • If the port is not open, a message such as the following will appear:
A failed connection will be accompanied by an error message. It can indicate either a closed port or the suggest that the indicated remote server is not listening on the provided port.
  • If the port is open, a blank screen will show up and sit idle while waiting for communication.
Press Ctrl+C to break the connection.

Keywords: telnet; not recognized as an internal or external command; install telnet; enable telnet; test port; check port; open port; listening; Windows Server Feature;

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