uidentd (mu-identd) is a fast and secure identd/auth server. It runs on Linux and any other OS that provides the virtual files, /proc/net/tcp and /proc/net/tcp6. It supports IPv6 natively. It is launched from a superserver such as xinetd or tcpserver and is supposedly resistant to buffer overflows since it is written in Perl. It supports configurable connection timeouts and multi-query as defined by RFC 1413.