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CrashPlan Support

Testing Your Network Connection With Telnet

Applies to:
  • CrashPlan for Home
Need enterprise or small business documentation?
This article is intended for CrashPlan for Home users. For Code42 CrashPlan and CrashPlan PRO documentation, read this page on our enterprise support site.

Overview

For most backup destinations, the CrashPlan app must have network access using specific ports. If your CrashPlan app cannot back up to the Code42 cloud or to another computer, you can test your CrashPlan app's network access using a tool called Telnet.

This article describes how to use Telnet to diagnose whether your CrashPlan app is affected by network issues, including conflicts from firewalls or antivirus software. You can use Telnet to test two types of connections:

Before you begin

On a Windows computer, you must turn on Telnet before you can use it.

  1. Click Start.
  2. Click Control Panel.
  3. Click Programs and Features.
  4. Click Turn Windows features on or off.
  5. Select the Telnet Client so that the checkbox is filled.
  6. Click OK.

On Linux or OS X, you can use Telnet by default.

Testing your connection to the Code42 cloud

Step 1: Run telnet

  1. Open a command prompt on your computer.
      • Windows:
        • Windows 10 and Windows 8: Start > All Apps > Windows System > Command Prompt
        • Windows 7: Start > All Programs > Accessories > Command Prompt
      • OS X: Applications > Utilities > Terminal
      • Linux: Open Terminal or another command prompt for your distribution.
  2. Enter the telnet command to test your connection to CrashPlan Central:
    telnet central.crashplan.com 443

Step 2: Read the telnet response

If your command prompt shows the following Connected message, your CrashPlan app can successfully connect to the Code42 cloud:

telnet central.crashplan.com 443
Trying 192.0.2.1...
Connected to central.crashplan.com.
Escape character is '^]'.
?cA-18782|com.code42.messaging.security.SecurityProviderReadyMessage??"???Q??????OM???`q?????N??6C:

If your command prompt shows anything else, your CrashPlan app cannot connect to the Code42 cloud. Common failure messages include:

  • Connection refused
  • Operation timed out
  • Unable to connect to remote host
  • No response

Step 3: Troubleshoot a failed connection

If your Telnet test did not connect to the Code42 cloud, your issue is caused by your computer or network, not by the CrashPlan app. Check the following common causes of this issue:

  • Your router's network configuration or port forwarding settings
  • Other conflicting software on your computer, such as antivirus, security, or parental control software

Testing your connection to another computer

Step 1: Identify the computer's network information

To test your connection to another computer, find the other computer's IP address and port.

On the other computer:

  1. Open the CrashPlan app.
  2. Go to Settings > Network.
  3. Record the other computer's Internal address and External address.
    Internal address and External address in the CrashPlan app

Step 2: Run telnet

Run the command telnet to diagnose the network connection between the two computers.

On your computer:

  1. Open a command prompt:
    • Windows:
      • Windows 10 and Windows 8: Start > All Apps > Windows System > Command Prompt
      • Windows 7: Start > All Programs > Accessories > Command Prompt
    • OS X: Applications > Utilities > Terminal
    • Linux: Open Terminal or another command prompt for your distribution.
  2. Enter the telnet command with the other computer's network information.
    Example: telnet 192.0.2.100 4242
    • Use the Internal address if both computers are on the same network, such as being in the same house.
    • Use the External address if the computers are on different networks, such as being in different houses.

Step 3: Read the telnet response

If your command prompt shows the following Connected message, your CrashPlan app can successfully connect to the other computer:

telnet 192.0.2.100 443
Trying 192.0.2.100...
Connected to 192.0.2.100.
Escape character is '^]'.
?cA-18782|com.code42.messaging.security.SecurityProviderReadyMessage??"???Q??????OM???`q?ʯ??N??6C:

If your command prompt shows anything else, your CrashPlan app cannot connect to the other computer. Common failure messages include:

  • Connection refused
  • Operation timed out
  • Unable to connect to remote host
  • No response

Step 4: Troubleshooting a failed connection

If your Telnet test did not connect to the other computer, your issue is caused by the configuration of your computers or network, not by the CrashPlan app. Check the following common causes of this issue:

  • Either computer's router, including its network configuration or port forwarding settings
  • Other conflicting software on either computer, such as antivirus, security, or parental control software

External references

These resources provide more information on the computer networking concepts in this article: