#define CEPH_MSGR_TAG_SEQ 13 /* 64-bit int follows with seen seq number */
#define CEPH_MSGR_TAG_KEEPALIVE2 14 /* keepalive2 byte + ceph_timespec */
#define CEPH_MSGR_TAG_KEEPALIVE2_ACK 15 /* keepalive2 reply */
-
+#define CEPH_MSGR_TAG_CHALLENGE_AUTHORIZER 16 /* cephx v2 doing server challenge */
/*
* connection negotiation