Ports & protocols

Port	Protocol	Direction	Purpose	Configurable with
64738	TCP	client to server	TLS handshake, control messages, chat, TCP fallback for voice	MUMBLE_CONFIG_PORT
64738	UDP	client to server	Voice and per-channel position data	same
64739	TCP	client to server	File server (emotes, attachments)	plugin.file-server.port
10000	UDP	client to server (in both directions)	Screen-share relay (WebRTC SFU)	MUMBLE_CONFIG_WEBRTCSFUPORT
6502	TCP	localhost only by default	Admin RPC (Ice)	Ice.Endpoint in config

Client to server only

The client always initiates the connection. The server never reaches back out, except for FCM push (server to Google) and link previews (server to the URL the user posted).

Outbound from the server

For a complete picture:

Destination	Protocol	When
Public DNS	UDP 53	Resolving hostnames
mumble.info directory	TCP 443	Public server listing (registerHostname set)
Firebase Cloud Messaging	TCP 443	Push notifications, if enabled
The URLs users paste	TCP 80/443	Link preview fetches, if enabled

Caution

If you self-host on an isolated network, the public-server-directory ping fails silently. That is fine; just turn it off with MUMBLE_CONFIG_REGISTERHOSTNAME="".

Firewall opening cheat sheet

A self-hosted server typically needs:

TCP  64738   inbound
UDP  64738   inbound
TCP  64739   inbound (if file server)
UDP  10000   inbound (if screen-share relay)
TCP    443   outbound (if push or link previews)

Common pitfalls

• UDP 64738 is blocked, voice falls back to TCP with a small latency hit. Force TCP under the client’s audio settings to make this consistent.
• UDP 10000 is filtered: viewers will see a black screen for shared streams. Open the port.
• Port collision with another service: change the server’s port with MUMBLE_CONFIG_PORT=12345. Clients then connect to your-host:12345.