Virtual Training

Why does the virtual machine need access on port 8080?

Our system utilizes a VNC client variation that allows a user to connect to their virtual hosts during training. Typically, VNC runs on port 5900, which is blocked by most DoD firewalls. Instead, we use port 8080, which allows most DoD users to connect to our system.

If a firewall is configured to block outbound port 8080 traffic, users will not be able to connect to their virtual machines. However, this port 8080 traffic only goes to our training servers though our firewall located at To test if you can access the virtual server, go to

If system administrators choose to limit the port 8080 traffic, we suggest they isolate port 8080 traffic to that IP to ensure that their users can still use our system.

To test your system for port 8080 access, please perform the following steps:

  • Select Start.
  • Choose Run.
  • Type "cmd" in the space provided and select "OK."
  • At the command prompt, type the following command: telnet 8080
  • Hit Enter.
    • If this results in a refused connection or can't establish connection, then port 8080 is not allowing traffic.
    • If the screen goes blank, this means that a connection has been established.
  • To exit the blank screen, type "CTRL+]" then type "Quit" at the command line and hit Enter. Then type "Exit" at the command line and hit Enter.

Per the Category Assurance List (CAL) from DISA, port 8080 is an acceptable port.