diff --git a/minestom-extensions/src/main/java/net/hollowcube/minestom/extensions/ExtensionBootstrap.java b/minestom-extensions/src/main/java/net/hollowcube/minestom/extensions/ExtensionBootstrap.java
index f811555..4ae4000 100644
--- a/minestom-extensions/src/main/java/net/hollowcube/minestom/extensions/ExtensionBootstrap.java
+++ b/minestom-extensions/src/main/java/net/hollowcube/minestom/extensions/ExtensionBootstrap.java
@@ -1,5 +1,6 @@
 package net.hollowcube.minestom.extensions;
 
+import net.minestom.server.Auth;
 import net.minestom.server.MinecraftServer;
 import net.minestom.server.extensions.ExtensionManager;
 import net.minestom.server.utils.validate.Check;
@@ -11,8 +12,28 @@
 public final class ExtensionBootstrap {
     private static ExtensionManager extensions = null;
 
+    /**
+     * Initialises the server with offline-mode authentication.
+     *
+     * @return the bootstrap to {@link #start(String, int)} once setup is done
+     */
     public static @NotNull ExtensionBootstrap init() {
-        return new ExtensionBootstrap(MinecraftServer.init());
+        return init(new Auth.Offline());
+    }
+
+    /**
+     * Initialises the server with the given authentication mode.
+     *
+     * <p>The {@link Auth} is bound to the {@code ServerProcess} by {@link MinecraftServer#init(Auth)}
+     * and cannot be swapped afterwards, so a server that sits behind a Velocity proxy has to pass
+     * {@link Auth.Velocity} here - there is no way to switch it on later.
+     *
+     * @param auth how incoming connections are authenticated, e.g. {@link Auth.Velocity} for a
+     *             server behind a Velocity proxy
+     * @return the bootstrap to {@link #start(String, int)} once setup is done
+     */
+    public static @NotNull ExtensionBootstrap init(@NotNull Auth auth) {
+        return new ExtensionBootstrap(MinecraftServer.init(auth));
     }
 
     public static @NotNull ExtensionManager getExtensionManager() {
diff --git a/minestom-extensions/src/test/java/net/hollowcube/minestom/extensions/ExtensionBootstrapAuthTest.java b/minestom-extensions/src/test/java/net/hollowcube/minestom/extensions/ExtensionBootstrapAuthTest.java
new file mode 100644
index 0000000..3096ad4
--- /dev/null
+++ b/minestom-extensions/src/test/java/net/hollowcube/minestom/extensions/ExtensionBootstrapAuthTest.java
@@ -0,0 +1,39 @@
+package net.hollowcube.minestom.extensions;
+
+import net.minestom.server.Auth;
+import net.minestom.server.MinecraftServer;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
+import static org.junit.jupiter.api.Assertions.assertSame;
+
+/**
+ * Pins that {@link ExtensionBootstrap} hands the caller's {@link Auth} to
+ * {@link MinecraftServer#init(Auth)}.
+ *
+ * <p>This is the whole point of the {@code init(Auth)} overload and it cannot be worked around from
+ * the outside: the {@code ServerProcess} keeps the {@link Auth} it was built with, so a bootstrap
+ * that silently called {@code MinecraftServer.init()} would leave every server behind a Velocity
+ * proxy on offline-mode authentication with no way to correct it afterwards.
+ */
+class ExtensionBootstrapAuthTest {
+
+    @Test
+    @DisplayName("init(Auth) binds the given auth to the server process")
+    void initWithAuthBindsGivenAuth() {
+        Auth.Velocity velocity = new Auth.Velocity("a-velocity-secret");
+
+        ExtensionBootstrap.init(velocity);
+
+        assertSame(velocity, MinecraftServer.process().auth());
+    }
+
+    @Test
+    @DisplayName("init() keeps defaulting to offline mode")
+    void initWithoutAuthDefaultsToOffline() {
+        ExtensionBootstrap.init();
+
+        assertInstanceOf(Auth.Offline.class, MinecraftServer.process().auth());
+    }
+}