# Alternative Authentication<\/p>\n
Alternative Authentication is a server-side mod that allows multiple third-party or custom authentication servers to coexist alongside Mojang’s. By default, two providers are configured: Mojang and Ely.by. You can add, remove, or reorder them freely.<\/p>\n
**Requirements:**<\/p>\n
– `online-mode=true` in `server.properties`
\n– `enforce-secure-profile=false` is recommended, players joining via third-party providers don’t have signed chat keys<\/p>\n
> **Server-side only.** Players using a third-party auth provider on the client need a compatible launcher or injector.<\/p>\n
## Features<\/p>\n
– \u2699\ufe0f Configurable list of authentication providers.
\n– \ud83d\udd10 Sequential provider fallback when a player joins the server
\n– \ud83d\udd12 Optional fallback prevention: if a username exists on a provider but authentication fails, further providers are not tried.
\n– \ud83d\udc55 Player texture support (skin and cape) via third-party skin servers
\n– \ud83d\udcdd Whitelist support across all configured providers<\/p>\n
## How It Works<\/p>\n
### Joining the Server<\/p>\n
When a player connects, each configured provider is tried in order until one successfully authenticates the session. If no provider succeeds, the player is denied access.<\/p>\n
If [`preventFallbackIfPlayerExists`](#preventfallbackifplayerexists) is enabled and a player’s username is found on a provider but authentication fails, no further providers are attempted. This prevents a user registered on a fallback service from impersonating an account on an earlier provider.<\/p>\n
### Whitelist<\/p>\n
When a player is added to the whitelist, each provider is queried in order until the username is resolved to a UUID. If the player is not found on any provider, they cannot be added. The order in which providers are checked is determined by the [`providers`](#providers) list in the config.<\/p>\n
#### What if two players share the same username across providers?<\/p>\n
By default, the first provider to resolve the username wins. If you need to whitelist a player whose username exists on a non-primary provider, temporarily reorder the [`providers`](#providers) list and add them manually with `\/whitelist add`.<\/p>\n
## Configuration<\/p>\n
The config file is created automatically at `config\/alternative-auth.json` on first launch.<\/p>\n
### `configVersion`<\/p>\n
The internal schema version. Managed automatically by the mod, do not edit this manually.<\/p>\n
### `debugMode`<\/p>\n
When `true`, detailed logs are written to the console during authentication and whitelist operations. Useful for troubleshooting. Disabled by default.<\/p>\n
### `preventFallbackIfPlayerExists`<\/p>\n
When `true`, stops the provider chain if a username is found on the current provider but authentication fails. Prevents username spoofing via fallback services, non-premium players with usernames unique to a fallback service are not affected. Disabled by default.<\/p>\n
### `providers`<\/p>\n
The ordered list of authentication providers. Each entry supports the following fields:<\/p>\n
| Field | Required | Description |
\n|—————|———-|—————————————————————————————————————————–|
\n| `name` | \u2705 | Display name for the provider |
\n| `checkUrl` | \u2705 | Session validation endpoint, queried when a player joins the server |
\n| `profileUrl` | \u2705 | Single username to UUID lookup endpoint, used for whitelist operations |
\n| `profilesUrl` | \u2705 | Batch username to UUID lookup endpoint |
\n| `propertyUrl` | \u274c | Endpoint for fetching player properties such as skin and cape. Use `{0}` for the player’s username and `{1}` for their UUID |<\/p>\n
“`json
\n{
\n “configVersion”: 1,
\n “debugMode”: false,
\n “preventFallbackIfPlayerExists”: false,
\n “providers”: [
\n {
\n “name”: “Mojang”,
\n “checkUrl”: “https:\/\/sessionserver.mojang.com\/session\/minecraft\/hasJoined”,
\n “profileUrl”: “https:\/\/api.minecraftservices.com\/minecraft\/profile\/lookup\/name\/”,
\n “profilesUrl”: “https:\/\/api.minecraftservices.com\/minecraft\/profile\/lookup\/bulk\/byname”
\n },
\n {
\n “name”: “Ely.by”,
\n “checkUrl”: “https:\/\/authserver.ely.by\/session\/hasJoined”,
\n “profileUrl”: “https:\/\/authserver.ely.by\/api\/users\/profiles\/minecraft\/”,
\n “profilesUrl”: “https:\/\/authserver.ely.by\/api\/profiles\/minecraft”,
\n “propertyUrl”: “http:\/\/skinsystem.ely.by\/textures\/signed\/{0}”
\n }
\n ]
\n}
\n“`<\/p>\n
## FAQ<\/p>\n
### Q: Can’t join the server, “Invalid signature for profile public key”<\/p>\n
A: Install No Chat Reports on your server. Installing it on the client is recommended but not required.<\/p>\n
### Q: Is Forge or NeoForge supported?<\/p>\n
A: NeoForge support is planned.<\/p>\n
### Q: When will the mod be updated to the latest Minecraft version?<\/p>\n
A: The mod targets the latest stable release and is updated as time allows. Snapshot support is not planned.<\/p>\n
### Q: I found a bug, have a suggestion, or the mod isn’t working correctly<\/p>\n
A: Feel free to open an issue on GitHub!<\/p>\n","protected":false},"excerpt":{"rendered":"
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