7503: Using telnet to Test Open Ports

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Last update: 23-06-2020

With the telnet command you can test if a port is open.


You can check if a port is open in your network by issuing the telnet command. If it is open, you will see a blank screen after issuing the command:

telnet [domainname or ip] [port]


  • [domainname or ip] is the domain name or IP address of the server to which you are trying to connect
  • [port] is the port number where the server is listening

If the port is open, you will see a blank screen. This will mean that connection is successful.

In Windows Vista and later you may need to enable telnet first:

  1. Go to Start -> Control Panel -> Programs.
  2. Under Programs and features, click Turn Windows features on or off.
  3. Mark both Telnet Client and Telnet Server.
  4. Click OK.


telnet rpc.acronis.com 443

Successful connection:

Port closed:

More information

If backup to Acronis Cloud is failing, use Acronis Cloud Connection Verification Tool to check the connection.