diff --git a/paramiko/auth_transport.py b/paramiko/auth_transport.py
index ba0cbec..2a6a1a2 100644
--- a/paramiko/auth_transport.py
+++ b/paramiko/auth_transport.py
@@ -97,7 +97,10 @@ class Transport (BaseTransport):
 
         @since: fearow
         """
-        return self.username
+        if self.server_mode:
+            return self.auth_username
+        else:
+            return self.username
 
     def auth_publickey(self, username, key, event):
         """