Running the GNS3 server as a daemon

You will find a sample init script for various systems inside the init directory of the gns3-server project:

Useful parameters to launch the server with are:

  • --daemon start process as a daemon
  • --log logfile store output in a logfile
  • --pid pidfile store the pid of the running process in a file and prevent double execution

All the init script require the creation of a GNS3 user. It is possible to change it to another user:

sudo adduser gns3

You will need to install some dependencies first. For example, in Ubuntu 18.04.3, you’ll need to install the following:


This does not install other items, like ubridge, qemu-kvm, docker, wireshark, etc… This just the necessary dependencies needed to build the gns3-server daemon.

In Bash, you can download the gns3-server code via the following command:

git clone

Next, enter the gns3-server directory that’s been created:

cd gns3-server

If you need a specific branch to match the version used by the clients, you can view a list of branches via this command:

git tag

Here’s an example of the list:


(hit Ctrl+Z to exit the list) To change the branch used, you’ll use this command:

git checkout tags/branch_version -b branch_version

For example, if the clients have GNS3 2.2.1 installed, you’ll use this command to build v2.2.1 of the gns3-server:

git checkout tags/v2.2.1 -b v2.2.1

Next, you’ll use this command to build the gns3-server daemon:

sudo python3 install

This step may take a few minutes to complete (it will vary, based on your PC), but upon successful completion, you’ll see this:


Next. you’ll need to enter the /gns3-server/init sub-directory, and copy one of two files. Which one you use, will depend on whether your version of linux uses upstart or systemd to launch daemons:+-


For ubuntu < 15.04

You must copy gns3.conf.upstart to /etc/init/gns3.conf and run these commands:

sudo cp gns3.conf.upstart /etc/init/gns3.conf
sudo chown root /etc/init/gns3.conf

To launch the daemon, use this command:

sudo service gns3 start


You must copy gns3.service.systemd to /lib/systemd/system/gns3.service and run these commands:

sudo cp gns3.service.systemd /lib/systemd/system/gns3.service
sudo chown root /lib/systemd/system/gns3.service

Run this command to start the gns3 daemon:

sudo systemctl start gns3

Next, run this command to ensure that the daemon is active and running, or see if there is an issue:

sudo systemctl status gns3

Ideally, you’ll see something like this:


(press Ctrl+Z to exit this screen. Doing so will not shut down the daemon.)

NOTE: you may need to allow TCP port 3080 through the firewall, if it isn’t already. In ubuntu, you’d use the following command:

sudo ufw allow 3080/tcp

To set the gns3-server daemon to always launch on boot/reload, use the following command:

sudo systemctl enable gns3

(you’ll see a symlink created)

At any time, you can run sudo systemctl status gns3 to check on the running daemon, as well as see which nodes it’s running on behalf of the clients . In the below example, it’s active, and running three instances of IOSv in a topology: