Scripted setup reduces the amount of time required to get the server up and running.

The script automatically makes a number of changes without prompting for confirmation, so we recommend you only run it on a fresh system where you don't mind having its state altered. The script relies on having an existing working Internet connection so it can download packages.


The gns3setup script will configure everything listed in the sections below. We have documented these steps separately only in case you need to to a manual setup or need to troubleshoot a configuration issue.

Fetch and run script

Login to your server as your normal user (e.g. "nsrc"), fetch the script and run it:

chmod +x gns3setup

The script uses sudo to run commands with root privileges, so will prompt you for your password as soon as it needs to.


It is safe to abort the script, and it is safe to run it multiple times - although it may overwrite files which you have manually changed to put them back how it thinks they should be.

Installation questions

Selecting network interfaces

The script will list your network interfaces and ask you to choose:

  • The LAN interface - where students and class wifi will connect
  • The WAN interface - the uplink for external Internet connectivity

If you have a built-in gigabit ethernet NIC then we recommend you choose that for the LAN. It will typically have a short name like eno1.

If you are using a USB NIC as your second NIC then we recommend you choose that for the WAN. It will typically have a long name containing the MAC address like enx086d41e68ba8.

If the script has picked the right interface already then just hit Enter to accept it.

For more information see reconfigure external ports in the manual setup instructions.


The script saves your LAN/WAN settings in a file gns3setup.conf so you don't have to re-enter them when re-running the script. Delete this file if you want to make a different selection.


For a cloud installation, where you have only a WAN interface, you should select "none" for the LAN interface.


You may be asked whether ubridge should be usable by non-root users. Say Yes.

netdata license

You may be asked to accept the netdata license. Say Yes.

Set GNS3 server password

The script creates a default username and password for your GNS3 server. It will be printed at the end of the output similar to the following:

All done!
password = XXXXXXXX

USERNAME will typically be the user you run the script under and XXXXXXXX will be your randomly generated password.

You can check for it in and edit /etc/gns3/gns3_server.conf . Note that the username and password are stored in cleartext and do not need to match your login username and password.

You will need to use this password when connecting your GNS3 client to manage the topologies.

Review and reboot server

The network changes won't take effect until you reboot the server. You may wish to inspect the modified files first.

If your existing Internet uplink is on the LAN port then you'll have to move it to the WAN port while the machine is rebooting.

Next steps

Once this is completed, test your classroom network - you should be able to connect a laptop and get a 100.64.0.x IP address and access the Internet via the WAN uplink on the server.

Once you are happy that this is working, you can skip straight to GNS3 Client and then load the NOC topology.