Steam Bridge

Steam Bridge

Steam Bridge redirects Minecraft’s network traffic through the Steam Datagram Relay (SDR) network. It allows players to host and join multiplayer worlds without port forwarding, public IP addresses, or third-party VPN software such as Hamachi or Radmin VPN.

The mod also supports compatible voice chat mods by tunneling UDP traffic through Steam Relay.

Discord Server: https://discord.gg/2xBnJ7awRC

The main place for bug reports, development updates, and changelogs.

Technical Details

Steam Bridge communicates directly with Steam’s internal ISteamNetworkingSockets API to establish relay-based connections through Steam Datagram Relay.

By default, the mod uses AppID 480 (Spacewar). This is Valve’s official Steamworks testing application, allowing Steam users to establish SDR connections without requiring ownership of a commercial Steam game.

The AppID is intentionally hardcoded. Allowing arbitrary AppIDs could encourage the use of commercial Steam applications, potentially violating Steam’s terms or triggering anti-cheat systems such as VAC or EAC.

Voice chat support works by optionally redirecting compatible UDP traffic through Steam Relay. This allows supported voice chat mods, such as Simple Voice Chat, to work without additional network configuration.

Configuration & Usage

• Virtual Port: Make sure no other application is using the configured virtual port before hosting. If necessary, change it in the configuration file.
• allowWithoutAuth: Controls Steam Session Ticket validation. Disabling this option requires every client to authenticate through Steam before the connection is accepted. This may reduce compatibility with certain NAT configurations.
• interceptUdp: Enables UDP tunneling for supported voice chat mods. Disable this option if another mod already replaces Java’s socket implementation.

Requirements

• A supported Minecraft version and mod loader.
• Windows x64. Linux support is planned.
• The official Steam client must be running on both the host and client.

Disclaimer

Steam Bridge is an independent open-source project and is not affiliated with, endorsed by, or authorized by Valve Corporation or Mojang Studios.

“Steam”, “Steamworks”, “Steam Datagram Relay”, and “Spacewar” are trademarks of Valve Corporation. “Minecraft” is a trademark of Mojang Studios.

The project redistributes the required Steamworks runtime (steam_api64.dll) under the Steamworks SDK license applicable to Steam developers.