Configure the server behind NAT

Warning

This guide only applies when transport=nethernet in server.properties. If you are still using RakNet, you do not need to read it.

Background

In server.properties, two options configure NetherNet: one for its signaling service and one for the UDP port actually used for client communication. They are server-port and server-udp-ports.

In short, the server creates an HTTP server on the port specified by server-port, so you need to allow TCP on that port in your firewall. It listens for UDP on the port or ports specified by server-udp-ports, so you need to allow UDP on that port or those ports in your firewall.

Tip

Since 26.60, server-udp-ports accepts either a single port or multiple ports, and defaults to listening on port 19132.
26.51 servers support only multiple ports, but LeviLamina also provides single-port support, which is enabled by default and listens on the same port as server-port. It can be disabled in LeviLamina's configuration file.

Configure port forwarding behind NAT with a public IP

Because server-port listens on TCP and server-udp-ports listens on UDP, you can set them to the same port, as the defaults in server.properties do. However, this guide is about configuring a server behind NAT, where the default configuration does not work, so you need to edit the configuration manually:

Open server.properties in the server directory with a text editor.
Find server-port and change it to a port your provider allows you to use, for example 11451.
Find server-udp-ports and change it to a port your provider allows you to use, for example 11451.
Configure port forwarding in your provider's control panel, mapping the internal port on the host (for example 11451) to the external port (for example 11451). Remember to forward both TCP and UDP.
Open the client and try to connect to the server.

Warning

Normally, a server with LeviLamina installed obtains its public IP through the built-in STUN servers. If that fails, the client may be unable to connect to the server, with error code Door.
In that case, change server-udp-ports to the following format:
server-udp-ports=<server public IP>:<port your provider allows you to use>:<local port>
For example: server-udp-ports=11.45.1.4:11451:11451
Then disable netherNetPatch in mods/LeviLamina/config/Config.json:

JSON

"netherNetPatch": {
     "enable": false, // change this from true to false
     "stunServers": [
         "stun:stun.l.google.com:19302",
         "stun:stun.miwifi.com:3478"
     ]
 }

Configure port forwarding through tunneling software such as frp behind NAT without a public IP

Open server.properties in the server directory with a text editor.
Find server-port and change it to a port your tunneling software allows you to use, for example 11451.
Find server-udp-ports and change it to the following format:
server-udp-ports=<exit node IP>:<port your tunneling software allows you to use>:<local port>
For example: server-udp-ports=11.45.1.4:11451:11451
Configure port forwarding in your tunneling software's control panel, mapping the internal port on the host (for example 11451) to the external port (for example 11451). Remember to forward both TCP and UDP.

Disable netherNetPatch in mods/LeviLamina/config/Config.json:

JSON

"netherNetPatch": {
     "enable": false, // change this from true to false
     "stunServers": [
         "stun:stun.l.google.com:19302",
         "stun:stun.miwifi.com:3478"
     ]
 }

Open the client and try to connect to the server.