Knowledge Base > Troubleshooting > Licensing network requirements

Licensing network requirements

Diffblue Cover needs an active internet connection to authorise its use. It needs to connect to both a Diffblue server and a LicenceSpring server, these servers are accessed on port 443:


To identify individual devices we transfer data about hardware components over this connection. Further details are available in the Privacy Notice.


  1. Check you have an active internet connection at all times when using Diffblue Cover.
  2. Ensure you can access via a web browser; you should be automatically redirected to the Diffblue website if this is successful.
  3. Ensure you can access via a web browser, you should see the message “no one is home”.
  4. Ensure that any Proxy Server settings are correctly setup (see the bottom of this page).
  5. Please speak to your network manager about whitelisting the URLs above, and checking that port 443 is open.
  6. For the Diffblue Cover IntelliJ Plugin, restart IntelliJ.
  7. Try temporarily disabling anti-virus, malware detector or any firewall software.
  8. A detailed logfile is available which shows further diagnostic information about the license check process - please review the logs:

For further help troubleshooting licensing network connection issues, please contact Diffblue Support.

Using a Proxy Server

Diffblue Cover IntelliJ Plugin

Please ensure you have the Proxy Server details configured in the IntelliJ settings page and then restart IntelliJ:

  • Windows and Linux: File | Settings | Appearance and Behavior | System Settings | HTTP Proxy
  • macOS: IntelliJ IDEA | Preferences | Appearance and Behavior | System Settings | HTTP Proxy

Diffblue Cover CLI

Diffblue Cover CLI utilizes the system Java proxy configurations; these can be set via the environment variable JVM_ARGS which details the proxy server FQDN and port, for example:

JVM_ARGS=" -Dhttps.proxyPort=8080"