System Administration
Which ports does GNS3 3.1 use? How to change port ranges?
| Purpose | Default Port Range | Description |
|---|---|---|
| Main service | 80 / 443 / 3080 | GNS3 VM default ports |
| Console ports | 5000-10000 | Device console connections |
| VNC ports | 5900-10000 | VNC connections |
| UDP communication | 10000-30000 | Inter-device link communication |
All port ranges can be customized in gns3_server.conf.
Compute node connection returns 401 Unauthorized?
- Check that
compute_usernameandcompute_passwordin the compute node config match the controller credentials - Verify the compute node configuration is loaded correctly
- Ensure the
[Server]section is used (not[Controller])
If compute_password is not set, the server generates a random 16-character password on startup, which will cause authentication failures.
Compute node reports "No common subnet" error?
Main cause: The controller's host is set to 0.0.0.0, causing it to register as 127.0.0.1, which is unreachable from the compute node.
Solution: Set the controller's host to its actual LAN IP address (e.g., host = 192.168.1.104) instead of 0.0.0.0. If using DHCP, configure a static lease on your router or use mDNS (.local domain).