For　locating　and　analyzing　the　secure　incidents　of　campus　network,　we　need　auto-logging　and　tracing　all　user＇s　information.　By　collecting　and　analyzing　the　data　from　user　authentification　log,　DHCP　log,　switch　log　and　router　log,　the　key　technologies　on　auto-logging　and　tracing　are　solved.　We　design　and　develop　a　prototype　system　and　deploy　it　in　our　campus　network.　Simulation　results　show　that　our　solution　is　valuable.