Network, ports and domain

The Network tab is the list of addresses the server can be heard on.

An allocation is one port on the machine, mapped into the container. A new server is given one automatically — without it the server would be unreachable, which is worse than a random number.

Each can carry an alias (game, rcon, voice), so a list of five ports says which is which. The protocol is TCP or UDP; voice mods and some games want UDP and stay silent on TCP.

The first allocation is the primary one. It is what fills the SERVER_PORT variable an egg substitutes into the startup command and the config. Change it and restart — a server reads its port at boot.

Adding or removing an allocation rebuilds the container. The data directory stays.

The panel opens a port on the machine. What sits in front of the machine is not its to control:

• The machine's firewall. The installer opens the panel's ports; game ports arrive later, so open those too.
• The router. On a home line the port has to travel from the internet to the machine. A port forward that does not come back after the router reboots looks exactly like a server that is down.

The address to hand to players is on the Players connect to line.

Connect domain is a name instead of a number. play.example.com instead of 89.20.14.7:26311.

For Minecraft the most useful thing is an SRV record: it carries the port too, so players type only the name even when the server is not on 25565.

_minecraft._tcp.play   SRV   0 5 26311 host.example.com.
host                   A     89.20.14.7

A plain A record works as well, but then players type the port themselves.

A domain opens no ports anywhere. It is a name, not a route — when the port does not work, the domain changes nothing about it.

Next: Startup and eggs.