diff --git a/src/cw/cw_in_check_join_req.c b/src/cw/cw_in_check_join_req.c
index 86549078..9d633181 100644
--- a/src/cw/cw_in_check_join_req.c
+++ b/src/cw/cw_in_check_join_req.c
@@ -4,6 +4,8 @@
 #include "dbg.h"
 #include "log.h"
 #include "capwap_items.h"
+#include "format.h"
+#include "connlist.h"
 
 int cw_in_check_join_req(struct conn *conn, struct cw_action_in *a, uint8_t * data,
 			 int len,struct sockaddr *from)
@@ -22,6 +24,17 @@ int cw_in_check_join_req(struct conn *conn, struct cw_action_in *a, uint8_t * da
 		cw_dbg_missing_mand(DBG_RFC,conn,mlist,n,a);
 	}
 
+	connlist_lock(conn->connlist);
+	struct conn *cc = connlist_get_by_session_id(conn->connlist,conn);
+	if (!cc){
+		connlist_add_by_session_id(conn->connlist,conn);
+	}
+	connlist_unlock(conn->connlist);
+	if (cc){
+		cw_dbg(DBG_ELEM_ERR,"Session already in use %s",format_bin2hex(conn->session_id,16));
+		conn->capwap_state=CW_STATE_JOIN;
+		return CW_RESULT_JOIN_FAILURE_SESSION_ALREADY_IN_USE;
+	}
 	
 	/* set result code to ok and change to configure state */
 	mbag_set_dword(conn->outgoing,CW_ITEM_RESULT_CODE,0);