Network and firewall · Basalt Docs

The ports Basalt uses, how devices find the host, and every request that leaves your network.

Ports

Port	Protocol	What it is for
7742	TCP	Every connection between a device and the host: files, video, and everything else. Always encrypted
7743	UDP	The host announcing itself on your network, so devices can list it without an address

Only the host listens on these. The apps on your devices only connect out to the host. Nothing needs to be opened on your router: Basalt works inside your home network, and nothing should be forwarded from the internet to it.

How devices find the host

The host announces itself on your local network every three seconds, on port 7743. Devices listen for it, and list each host they hear with its name.

Each host is known by its identity, not its address. When the router gives the host a different address, devices simply find it at the new one. If announcements can’t cross your network, as on some guest networks and mesh systems, a device can pair by address instead.

Firewall rules

System	Let devices through
Windows	Allow Basalt Host on private networks when Windows asks, or in Windows Security, Firewall & network protection, Allow an app through firewall
Ubuntu, Debian (ufw)	`sudo ufw allow "Basalt Host"`
Fedora, Rocky (firewalld)	`sudo firewall-cmd --permanent --add-service=basalt-host` then `sudo firewall-cmd --reload`
Anything else	Allow 7742/tcp and 7743/udp in

The Linux packages include the ufw profile and the firewalld service, so the commands above work once Basalt Host is installed.

Docker networking

With network_mode: host, the container uses the computer’s own network, and devices find it like any other host. Without it, publish both ports and pair by address:

ports:
  - "7742:7742/tcp"
  - "7743:7743/udp"

What leaves your network

Your files never leave your home network. The only requests Basalt makes beyond it are:

Request	From	When
The update check, to GitHub	The host and the apps	A minute after starting, then twice a day, for the host; when the app opens, then twice a day while it stays open, for the apps
Downloading an update, from GitHub	The host and the apps	When an update is installed
Poster lookups	The host	Only with Download posters on: the titles of recognised films and series, never the files

The update check asks GitHub for the newest release; GitHub sees the request as it would any other, with your network’s address. No account, identifier or information about your drive is sent. See the privacy policy for the details.

In Docker, pulling the image from the GitHub Container Registry is also a request to GitHub, made by you.