--- a/svr-auth.c	Thu May 09 23:27:23 2013 +0800
+++ b/svr-auth.c	Tue May 21 12:09:35 2013 +0800
@@ -225,6 +225,7 @@
 
 	char* listshell = NULL;
 	char* usershell = NULL;
+	int   uid;
 	TRACE(("enter checkusername"))
 	if (userlen > MAX_USERNAME_LEN) {
 		return DROPBEAR_FAILURE;
@@ -254,6 +255,18 @@
 		return DROPBEAR_FAILURE;
 	}
 
+	/* check if we are running as non-root, and login user is different from the server */
+	uid = geteuid();
+	if (uid != 0 && uid != ses.authstate.pw_uid) {
+		TRACE(("running as nonroot, only server uid is allowed"))
+		dropbear_log(LOG_WARNING,
+				"Login attempt with wrong user %s from %s",
+				ses.authstate.pw_name,
+				svr_ses.addrstring);
+		send_msg_userauth_failure(0, 1);
+		return DROPBEAR_FAILURE;
+	}
+
 	/* check for non-root if desired */
 	if (svr_opts.norootlogin && ses.authstate.pw_uid == 0) {
 		TRACE(("leave checkusername: root login disabled"))