VIAaaS

VIAaaS - ViaVersion acetylsalicylic acid as a Service - Standalone ViaVersion proxy

Public instances: https://github.com/ViaVersion/VIAaaS/wiki/List-of-Public-Instances

Discord: https://viaversion.com/discord

Supported versions: https://viaversion.com/

How does it work?

• ViaVersion, ViaBackwards and ViaRewind translates the connections to backend server.
• VIAaaS auth page stores account credentials in the player's browser local storage. Check for XSS vulnerabilities on your domain.
• Due to technical/security reasons, it requires a CORS Proxy for calling Mojang APIs, which may make Mojang see that as suspicious and reset/block your account password if the IP address seems suspect.
• Account credentials aren't sent to VIAaaS instance, though it's intermediated by CORS Proxy.
• VIAaaS receives a the session hash from instance and then the browser validates it to Mojang.

Setting up server instance

Download: GitHub Actions (needs to be logged into GitHub) or JitPack

How to start VIAaaS server:

java -jar VIAaaS-all.jar

• Requires Java 11
• Default Minecraft: via.localhost with port 25565
• Default HTTPS: https://localhost:25543/
• Default WS URL: wss://localhost:25543/ws

How to create a public server

• You need a domain wildcarding to VIAaaS instance, like *.example.com -> 192.168.123.123. You can use DuckDNS DDNS service.
• Configure the hostname in the config
• Open the Minecraft port (25565)
• The HTTPS page needs a certificate, you can use Apache (with a Let's Encrypt certificate) as a proxy. See apache_copypasta.txt file.

CORS Proxy

• For less chance of Mojang seeing the login as suspect, you (the player) should set up a CORS proxy on your machine.
• Note the ending slash in cors-anywhere address
• You can use my public instance at https://crp123-cors.herokuapp.com/ (source) too, but proxies have a bit more chance of being seen as suspect.

Setting up cors-anywhere on local machine:

git clone https://github.com/Rob--W/cors-anywhere
cd cors-anywhere
npm install
node server.js

• It will be available at http://localhost:8080/

Usage for players

Usage for offline mode:

• Connect to mc.example.net.via.localhost

Usage for online mode:

• You can use two accounts (avoids Bad Login error), the same account for front-end and back-end connections, or use _of (offline mode in frontend. May be useful if you have a client which is incompatible with online mode).
• Go to VIAaaS auth webpage (default is https://localhost:25543/)
• Configure CORS proxy, see above in "CORS Proxy" section
• Listen to the username A you'll use to connect to the proxy.
• Add the account B to VIAaaS page which you'll use in _u parameter below.
• Keep the page open
• Connect to mc.example.com._u(B).via.localhost (_u can be removed if you are using the same username)
• Approve the login in the webpage
• If you use the same online mode account, your client may show Bad Login. You can use a mod like Auth Me or ReAuth.

Address options

Example address:

• server.example.net._p25565._v1_12_2._of._uBACKUSERNAME.via.example.com
• server.example.net.v_1_8.via.example.com
• It's inspired by Tor2web proxies.

Address parts:

• You can use (option)_(value) too, like p_25565.
• server.example.net: backend server address
• _p: backend port
• _v: backend version (protocol id or name with underline instead of dots). AUTO is default and -1 is fallback if it fails.
• _o: t to force online mode in frontend, f to disable online mode in frontend. If not set, it will be based on backend online mode.
• _u: username to use in backend connection
• via.example.com: instance address (defined in config)

WARNING

• VIAaaS may trigger anti-cheats, due to block, item, movement and other differences between versions. USE AT OWN RISK
• Take care of browser local storage. Check for XSS vulnerabilities on your domain.
• Check the security of CORS proxy, it will intermediate Mojang API calls.
• Mojang may lock your account when API is called from a suspect IP address

FAQ

Accounts

My Microsoft account <18 years old is not able to log in, it's giving XSTS error:

• Add your account to a family (see https://wiki.vg/Microsoft_Authentication_Scheme#Authenticate_with_XSTS)

Why a online webpage for online mode?:

• It's easier to maintain in that way, because providing login via chat requires encoding and decoding more packets which change through versions.
• It allows your account password and token to be kept with you.

How to use Microsoft Account?:

• If you are using a public VIAaaS instance, use this page https://viaversion.github.io/VIAaaS/ and configure the WebSocket address.

Connection

How to use IPv6?:

• When listening to 0.0.0.0, it should listen on IPv6 too.
• To use IPv6 in backend address, you need to use a instance with IPv6 connectivity. The hostname parser currently doesn't support direct IPv6, but you can use a DNS name with https://sslip.io/

I'm getting a DNS error/"Unknown host" while connecting to (...).localhost

• Try configuring via-127-0-0-1.nip.io as hostname suffix

How to use with Geyser?

• Currently you need to set the parameters (at least the hostname) in Geyser's address field:

  remote:
    # The IP address of the remote (Java Edition) server
    address: 2b2t.org._v1_12_2.via.localhost
  

• If you are using a public GeyserConnect instance: connect to a publicly available VIAaaS instance, like mc.example.com.via.example.net as a Java Edition server.

Can I use it to connect to .onion Minecraft hidden servers?

• You can use .onion addresses if the instance is proxying the backend connections to TOR. Note that VIAaaS may log your requests.

Can you support more versions?

• See DirtMultiVersion