diff --git a/src/rpc/inc/rpcHead.h b/src/rpc/inc/rpcHead.h
index 9bbcd60fc4d386b9afc1b52c82b9cbe645193f7a..8b5410a596ae64a27ebecc9e3591fa90de044323 100644
--- a/src/rpc/inc/rpcHead.h
+++ b/src/rpc/inc/rpcHead.h
@@ -48,7 +48,7 @@ typedef struct {
   char     spi:3;     // security parameter index
   char     encrypt:3; // encrypt algorithm, 0: no encryption
   uint16_t tranId;    // transcation ID
-  uint32_t uid;       // for unique ID inside a client
+  uint32_t linkUid;   // for unique connection ID assigned by client
   uint32_t sourceId;  // source ID, an index for connection list  
   uint32_t destId;    // destination ID, an index for connection list
   uint32_t destIp;    // destination IP address, for NAT scenario
diff --git a/src/rpc/src/rpcMain.c b/src/rpc/src/rpcMain.c
index 17e8a944083528f33d02b547dd3ceadb4a334b5f..e596aaa3e88f89f755446cf25b159db6b91b6343 100755
--- a/src/rpc/src/rpcMain.c
+++ b/src/rpc/src/rpcMain.c
@@ -96,7 +96,7 @@ typedef struct _RpcConn {
   char      ckey[TSDB_KEY_LEN];   // ciphering key 
   char      secured;              // if set to 1, no authentication
   uint16_t  localPort;      // for UDP only
-  uint32_t  peerUid;        // peer UID
+  uint32_t  linkUid;        // connection unique ID assigned by client
   uint32_t  peerIp;         // peer IP
   uint32_t  destIp;         // server destination IP to handle NAT 
   uint16_t  peerPort;       // peer port
@@ -400,10 +400,9 @@ void rpcSendResponse(void *handle, int32_t code, void *pCont, int contLen) {
   pHead->tranId = pConn->inTranId;
   pHead->sourceId = pConn->ownId;
   pHead->destId = pConn->peerId;
-  pHead->uid = 0;
+  pHead->linkUid = pConn->linkUid;
   pHead->port = htons(pConn->localPort);
   pHead->code = htonl(code);
-  memcpy(pHead->user, pConn->user, tListLen(pHead->user));
 
   // set pConn parameters
   pConn->inType = 0;
@@ -499,7 +498,7 @@ static void rpcCloseConn(void *thandle) {
 
     if ( pRpc->connType == TAOS_CONN_SERVER) {
       char hashstr[40] = {0};
-      sprintf(hashstr, "%x:%x:%x:%d", pConn->peerIp, pConn->peerUid, pConn->peerId, pConn->connType);
+      sprintf(hashstr, "%x:%x:%x:%d", pConn->peerIp, pConn->linkUid, pConn->peerId, pConn->connType);
       taosDeleteStrHash(pRpc->hash, hashstr);
       rpcFreeMsg(pConn->pRspMsg); // it may have a response msg saved, but not request msg
       pConn->pRspMsg = NULL;
@@ -535,6 +534,7 @@ static SRpcConn *rpcAllocateClientConn(SRpcInfo *pRpc) {
     pConn->sid = sid;
     pConn->tranId = (uint16_t)(rand() & 0xFFFF);
     pConn->ownId = htonl(pConn->sid);
+    pConn->linkUid = (uint32_t)((int64_t)pConn + (int64_t)getpid());
     pConn->spi = pRpc->spi;
     pConn->encrypt = pRpc->encrypt;
     if (pConn->spi) memcpy(pConn->secret, pRpc->secret, TSDB_KEY_LEN);
@@ -548,7 +548,7 @@ static SRpcConn *rpcAllocateServerConn(SRpcInfo *pRpc, SRecvInfo *pRecv) {
   char      hashstr[40] = {0};
   SRpcHead *pHead = (SRpcHead *)pRecv->msg;
 
-  sprintf(hashstr, "%x:%x:%x:%d", pRecv->ip, pHead->uid, pHead->sourceId, pRecv->connType);
+  sprintf(hashstr, "%x:%x:%x:%d", pRecv->ip, pHead->linkUid, pHead->sourceId, pRecv->connType);
  
   // check if it is already allocated
   SRpcConn **ppConn = (SRpcConn **)(taosGetStrHashData(pRpc->hash, hashstr));
@@ -567,6 +567,7 @@ static SRpcConn *rpcAllocateServerConn(SRpcInfo *pRpc, SRecvInfo *pRecv) {
     pConn->sid = sid;
     pConn->tranId = (uint16_t)(rand() & 0xFFFF);
     pConn->ownId = htonl(pConn->sid);
+    pConn->linkUid = pHead->linkUid;
     if (pRpc->afp && (*pRpc->afp)(pConn->user, &pConn->spi, &pConn->encrypt, pConn->secret, pConn->ckey) < 0) {
       tWarn("%s %p, user not there", pRpc->label, pConn);
       taosFreeId(pRpc->idPool, sid);   // sid shall be released
@@ -601,8 +602,8 @@ static SRpcConn *rpcGetConnObj(SRpcInfo *pRpc, int sid, SRecvInfo *pRecv) {
   } 
 
   if (pConn) {
-    if (memcmp(pConn->user, pHead->user, tListLen(pConn->user)) != 0) {
-      tTrace("%s %p, user:%s is not matched, received:%s", pRpc->label, pConn, pConn->user, pHead->user);
+    if (pConn->linkUid != pHead->linkUid) {
+      tTrace("%s %p, linkUid:0x%x not matched, received:0x%x", pRpc->label, pConn, pConn->linkUid, pHead->linkUid);
       terrno = TSDB_CODE_MISMATCHED_METER_ID;
       pConn = NULL;
     }
@@ -748,7 +749,6 @@ static SRpcConn *rpcProcessMsgHead(SRpcInfo *pRpc, SRecvInfo *pRecv) {
   
   if (pRecv->port) pConn->peerPort = pRecv->port;
   if (pHead->port) pConn->peerPort = htons(pHead->port); 
-  if (pHead->uid) pConn->peerUid = pHead->uid;
 
   terrno = rpcCheckAuthentication(pConn, (char *)pHead, pRecv->msgLen);
 
@@ -881,7 +881,7 @@ static void rpcSendQuickRsp(SRpcConn *pConn, int32_t code) {
   pHead->tranId = pConn->inTranId;
   pHead->sourceId = pConn->ownId;
   pHead->destId = pConn->peerId;
-  pHead->uid = 0;
+  pHead->linkUid = pConn->linkUid;
   memcpy(pHead->user, pConn->user, tListLen(pHead->user));
   pHead->code = htonl(code);
 
@@ -905,7 +905,7 @@ static void rpcSendErrorMsgToPeer(SRecvInfo *pRecv, int32_t code) {
   pReplyHead->tranId = pRecvHead->tranId;
   pReplyHead->sourceId = pRecvHead->destId;
   pReplyHead->destId = pRecvHead->sourceId;
-  memcpy(pReplyHead->user, pRecvHead->user, tListLen(pReplyHead->user));
+  pReplyHead->linkUid = pRecvHead->linkUid;
 
   pReplyHead->code = htonl(code);
   msgLen = sizeof(SRpcHead);
@@ -951,8 +951,8 @@ static void rpcSendReqToServer(SRpcInfo *pRpc, SRpcReqContext *pContext) {
   pHead->destId = pConn->peerId;
   pHead->destIp = pConn->destIp;
   pHead->port = 0;
-  pHead->uid = (uint32_t)((int64_t)pConn + (int64_t)getpid());
-  memcpy(pHead->user, pConn->user, tListLen(pHead->user));
+  pHead->linkUid = pConn->linkUid;
+  if (!pConn->secured) memcpy(pHead->user, pConn->user, tListLen(pHead->user));
 
   // set the connection parameters
   pConn->outType = msgType;