diff --git a/include/rfb/rfb.h b/include/rfb/rfb.h
index de083d7b..ecd82904 100644
--- a/include/rfb/rfb.h
+++ b/include/rfb/rfb.h
@@ -147,6 +147,11 @@ typedef struct {
   } data; /**< there have to be count*3 entries */
 } rfbColourMap;
 
+enum rfbSecurityTag {
+    RFB_SECURITY_TAG_NONE = 0,
+    RFB_SECURITY_TAG_CHANNEL = 1 << 0
+};
+
 /**
  * Security handling (RFB protocol version 3.7)
  */
@@ -155,6 +160,7 @@ typedef struct _rfbSecurity {
 	uint8_t type;
 	void (*handler)(struct _rfbClientRec* cl);
 	struct _rfbSecurity* next;
+	enum rfbSecurityTag securityTags;
 } rfbSecurityHandler;
 
 /**
@@ -402,6 +408,14 @@ typedef struct sraRegion* sraRegionPtr;
 typedef void (*ClientGoneHookPtr)(struct _rfbClientRec* cl);
 typedef void (*ClientFramebufferUpdateRequestHookPtr)(struct _rfbClientRec* cl, rfbFramebufferUpdateRequestMsg* furMsg);
 
+typedef int (*ClientReadFromSocket)(struct _rfbClientRec* cl,
+                                    char *buf, int len);
+typedef int (*ClientPeekAtSocket)(struct _rfbClientRec* cl,
+                                  char *buf, int len);
+typedef rfbBool (*ClientHasPendingOnSocket)(struct _rfbClientRec* cl);
+typedef int (*ClientWriteToSocket)(struct _rfbClientRec* cl,
+                                   const char *buf, int len);
+
 typedef struct _rfbFileTransferData {
   int fd;
   int compressionEnabled;
@@ -496,7 +510,9 @@ typedef struct _rfbClientRec {
          * using LibVNCServer to provide services: */
 
         RFB_INITIALISATION_SHARED, /**< sending initialisation messages with implicit shared-flag already true */
-        RFB_SHUTDOWN            /**< Client is shutting down */
+        RFB_SHUTDOWN,           /**< Client is shutting down */
+
+        RFB_CHANNEL_SECURITY_TYPE, /**< negotiating security (RFB v.3.7) */
     } state;
 
     rfbBool reverseConnection;
@@ -715,6 +731,11 @@ typedef struct _rfbClientRec {
     int destPort;
     /** ID on repeater in case of an UltraVNC mode 2 repeater connection */
     char *repeaterId;
+
+    ClientReadFromSocket readFromSocket;         /* Read data from socket */
+    ClientPeekAtSocket peekAtSocket;             /* Peek at data from socket */
+    ClientHasPendingOnSocket hasPendingOnSocket; /* Has pending data on socket */
+    ClientWriteToSocket writeToSocket;           /* Write data to socket */
 } rfbClientRec, *rfbClientPtr;
 
 /**
@@ -767,8 +788,12 @@ extern void rfbDisconnectUDPSock(rfbScreenInfoPtr rfbScreen);
 extern void rfbCloseClient(rfbClientPtr cl);
 extern int rfbReadExact(rfbClientPtr cl, char *buf, int len);
 extern int rfbReadExactTimeout(rfbClientPtr cl, char *buf, int len,int timeout);
+extern int rfbDefaultReadFromSocket(rfbClientPtr cl, char *buf, int len);
 extern int rfbPeekExactTimeout(rfbClientPtr cl, char *buf, int len,int timeout);
+extern int rfbDefaultPeekAtSocket(rfbClientPtr cl, char *buf, int len);
+extern rfbBool rfbDefaultHasPendingOnSocket(rfbClientPtr cl);
 extern int rfbWriteExact(rfbClientPtr cl, const char *buf, int len);
+extern int rfbDefaultWriteToSocket(rfbClientPtr cl, const char *buf, int len);
 extern int rfbCheckFds(rfbScreenInfoPtr rfbScreen,long usec);
 extern rfbSocket rfbConnect(rfbScreenInfoPtr rfbScreen, char* host, int port);
 extern rfbSocket rfbConnectToTcpAddr(char* host, int port);
@@ -874,6 +899,9 @@ extern void rfbProcessClientSecurityType(rfbClientPtr cl);
 extern void rfbAuthProcessClientMessage(rfbClientPtr cl);
 extern void rfbRegisterSecurityHandler(rfbSecurityHandler* handler);
 extern void rfbUnregisterSecurityHandler(rfbSecurityHandler* handler);
+extern void rfbRegisterChannelSecurityHandler(rfbSecurityHandler* handler);
+extern void rfbUnregisterChannelSecurityHandler(rfbSecurityHandler* handler);
+extern void rfbSendSecurityTypeList(rfbClientPtr cl, enum rfbSecurityTag exclude);
 
 /* rre.c */
 
diff --git a/src/common/crypto.h b/src/common/crypto.h
index 04be9304..c1f32194 100644
--- a/src/common/crypto.h
+++ b/src/common/crypto.h
@@ -11,7 +11,9 @@
 int hash_md5(void *out, const void *in, const size_t in_len);
 
 /* Generates an SHA1 hash of 'in' and writes it to 'out', which must be 20 bytes in size. */
+#ifdef LIBVNCSERVER_WITH_WEBSOCKETS
 int hash_sha1(void *out, const void *in, const size_t in_len);
+#endif
 
 /* Fill 'out' with 'len' random bytes. */
 void random_bytes(void *out, size_t len);
diff --git a/src/common/crypto_included.c b/src/common/crypto_included.c
index b359336f..cf8d43c2 100644
--- a/src/common/crypto_included.c
+++ b/src/common/crypto_included.c
@@ -33,6 +33,7 @@ int hash_md5(void *out, const void *in, const size_t in_len)
     return 0;
 }
 
+#ifdef LIBVNCSERVER_WITH_WEBSOCKETS
 int hash_sha1(void *out, const void *in, const size_t in_len)
 {
     SHA1Context sha1;
@@ -45,6 +46,7 @@ int hash_sha1(void *out, const void *in, const size_t in_len)
 
     return 1;
 }
+#endif /* LIBVNCSERVER_WITH_WEBSOCKETS */
 
 void random_bytes(void *out, size_t len)
 {
diff --git a/src/common/crypto_libgcrypt.c b/src/common/crypto_libgcrypt.c
index 34d845b4..f62bdaf8 100644
--- a/src/common/crypto_libgcrypt.c
+++ b/src/common/crypto_libgcrypt.c
@@ -74,6 +74,7 @@ int hash_md5(void *out, const void *in, const size_t in_len)
     return result;
 }
 
+#ifdef LIBVNCSERVER_WITH_WEBSOCKETS
 int hash_sha1(void *out, const void *in, const size_t in_len)
 {
     int result = 0;
@@ -98,6 +99,7 @@ int hash_sha1(void *out, const void *in, const size_t in_len)
     gcry_md_close(sha1);
     return result;
 }
+#endif /* LIBVNCSERVER_WITH_WEBSOCKETS */
 
 void random_bytes(void *out, size_t len)
 {
diff --git a/src/common/crypto_openssl.c b/src/common/crypto_openssl.c
index 28f04272..6bf9646c 100644
--- a/src/common/crypto_openssl.c
+++ b/src/common/crypto_openssl.c
@@ -52,6 +52,7 @@ int hash_md5(void *out, const void *in, const size_t in_len)
     return 1;
 }
 
+#ifdef LIBVNCSERVER_WITH_WEBSOCKETS
 int hash_sha1(void *out, const void *in, const size_t in_len)
 {
     SHA_CTX sha1;
@@ -63,6 +64,7 @@ int hash_sha1(void *out, const void *in, const size_t in_len)
 	return 0;
     return 1;
 }
+#endif /* LIBVNCSERVER_WITH_WEBSOCKETS */
 
 void random_bytes(void *out, size_t len)
 {
diff --git a/src/libvncserver/auth.c b/src/libvncserver/auth.c
index 748027b1..52ea2a36 100644
--- a/src/libvncserver/auth.c
+++ b/src/libvncserver/auth.c
@@ -37,18 +37,17 @@ void rfbClientSendString(rfbClientPtr cl, const char *reason);
  * Handle security types
  */
 
+/* Channel security handlers to set up a secure channel, e.g. TLS. */
+static rfbSecurityHandler* channelSecurityHandlers = NULL;
+
+/* Security handlers when channel security is established. */
 static rfbSecurityHandler* securityHandlers = NULL;
 
-/*
- * This method registers a list of new security types.  
- * It avoids same security type getting registered multiple times. 
- * The order is not preserved if multiple security types are
- * registered at one-go.
- */
 void
-rfbRegisterSecurityHandler(rfbSecurityHandler* handler)
+rfbRegisterSecurityHandlerTo(rfbSecurityHandler* handler,
+                             rfbSecurityHandler** handlerList)
 {
-	rfbSecurityHandler *head = securityHandlers, *next = NULL;
+	rfbSecurityHandler *head = *handlerList, *next = NULL;
 
 	if(handler == NULL)
 		return;
@@ -57,39 +56,35 @@ rfbRegisterSecurityHandler(rfbSecurityHandler* handler)
 
 	while(head != NULL) {
 		if(head == handler) {
-			rfbRegisterSecurityHandler(next);
+			rfbRegisterSecurityHandlerTo(next, handlerList);
 			return;
 		}
 
 		head = head->next;
 	}
 
-	handler->next = securityHandlers;
-	securityHandlers = handler;
+	handler->next = *handlerList;
+	*handlerList = handler;
 
-	rfbRegisterSecurityHandler(next);
+	rfbRegisterSecurityHandlerTo(next, handlerList);
 }
 
-/*
- * This method unregisters a list of security types. 
- * These security types won't be available for any new
- * client connection. 
- */
-void
-rfbUnregisterSecurityHandler(rfbSecurityHandler* handler)
+static void
+rfbUnregisterSecurityHandlerFrom(rfbSecurityHandler* handler,
+                                 rfbSecurityHandler** handlerList)
 {
 	rfbSecurityHandler *cur = NULL, *pre = NULL;
 
 	if(handler == NULL)
 		return;
 
-	if(securityHandlers == handler) {
-		securityHandlers = securityHandlers->next;
-		rfbUnregisterSecurityHandler(handler->next);
+	if(*handlerList == handler) {
+		*handlerList = (*handlerList)->next;
+		rfbUnregisterSecurityHandlerFrom(handler->next, handlerList);
 		return;
 	}
 
-	cur = pre = securityHandlers;
+	cur = pre = *handlerList;
 
 	while(cur) {
 		if(cur == handler) {
@@ -99,7 +94,50 @@ rfbUnregisterSecurityHandler(rfbSecurityHandler* handler)
 		pre = cur;
 		cur = cur->next;
 	}
-	rfbUnregisterSecurityHandler(handler->next);
+	rfbUnregisterSecurityHandlerFrom(handler->next, handlerList);
+}
+
+void
+rfbRegisterChannelSecurityHandler(rfbSecurityHandler* handler)
+{
+    rfbRegisterSecurityHandlerTo(handler, &channelSecurityHandlers);
+}
+
+/*
+ * This method unregisters a list of security types.
+ * These security types won't be available for any new
+ * client connection.
+ */
+
+void
+rfbUnregisterChannelSecurityHandler(rfbSecurityHandler* handler)
+{
+    rfbUnregisterSecurityHandlerFrom(handler, &channelSecurityHandlers);
+}
+
+/*
+ * This method registers a list of new security types.
+ * It avoids same security type getting registered multiple times.
+ * The order is not preserved if multiple security types are
+ * registered at one-go.
+ */
+
+void
+rfbRegisterSecurityHandler(rfbSecurityHandler* handler)
+{
+    rfbRegisterSecurityHandlerTo(handler, &securityHandlers);
+}
+
+/*
+ * This method unregisters a list of security types.
+ * These security types won't be available for any new
+ * client connection.
+ */
+
+void
+rfbUnregisterSecurityHandler(rfbSecurityHandler* handler)
+{
+    rfbUnregisterSecurityHandlerFrom(handler, &securityHandlers);
 }
 
 /*
@@ -197,9 +235,22 @@ static rfbSecurityHandler VncSecurityHandlerNone = {
     NULL
 };
                         
+static int32_t
+determinePrimarySecurityType(rfbClientPtr cl)
+{
+    if (!cl->screen->authPasswdData || cl->reverseConnection) {
+        /* chk if this condition is valid or not. */
+        return rfbSecTypeNone;
+    } else if (cl->screen->authPasswdData) {
+        return rfbSecTypeVncAuth;
+    } else {
+        return rfbSecTypeInvalid;
+    }
+}
 
-static void
-rfbSendSecurityTypeList(rfbClientPtr cl, int primaryType)
+void
+rfbSendSecurityTypeList(rfbClientPtr cl,
+                        enum rfbSecurityTag exclude)
 {
     /* The size of the message is the count of security types +1,
      * since the first byte is the number of types. */
@@ -207,9 +258,10 @@ rfbSendSecurityTypeList(rfbClientPtr cl, int primaryType)
     rfbSecurityHandler* handler;
 #define MAX_SECURITY_TYPES 255
     uint8_t buffer[MAX_SECURITY_TYPES+1];
-
+    int32_t primaryType;
 
     /* Fill in the list of security types in the client structure. (NOTE: Not really in the client structure) */
+    primaryType = determinePrimarySecurityType(cl);
     switch (primaryType) {
     case rfbSecTypeNone:
 	rfbUnregisterSecurityHandler(&VncSecurityHandlerVncAuth);
@@ -223,6 +275,9 @@ rfbSendSecurityTypeList(rfbClientPtr cl, int primaryType)
 
     for (handler = securityHandlers;
 	    handler && size<MAX_SECURITY_TYPES; handler = handler->next) {
+	if (exclude && (handler->securityTags & exclude))
+	    continue;
+
 	buffer[size] = handler->type;
 	size++;
     }
@@ -251,7 +306,29 @@ rfbSendSecurityTypeList(rfbClientPtr cl, int primaryType)
     cl->state = RFB_SECURITY_TYPE;
 }
 
+static void
+rfbSendChannelSecurityTypeList(rfbClientPtr cl)
+{
+    int size = 1;
+    rfbSecurityHandler* handler;
+    uint8_t buffer[MAX_SECURITY_TYPES+1];
+
+    for (handler = channelSecurityHandlers;
+	    handler && size<MAX_SECURITY_TYPES; handler = handler->next) {
+	buffer[size] = handler->type;
+	size++;
+    }
+    buffer[0] = (unsigned char)size-1;
+
+    if (rfbWriteExact(cl, (char *)buffer, size) < 0) {
+	rfbLogPerror("rfbSendSecurityTypeList: write");
+	rfbCloseClient(cl);
+	return;
+    }
 
+    /* Dispatch client input to rfbProcessClientChannelSecurityType. */
+    cl->state = RFB_CHANNEL_SECURITY_TYPE;
+}
 
 
 /*
@@ -299,18 +376,19 @@ rfbSendSecurityType(rfbClientPtr cl, int32_t securityType)
 void
 rfbAuthNewClient(rfbClientPtr cl)
 {
-    int32_t securityType = rfbSecTypeInvalid;
+    int32_t securityType;
 
-    if (!cl->screen->authPasswdData || cl->reverseConnection) {
-	/* chk if this condition is valid or not. */
-	securityType = rfbSecTypeNone;
-    } else if (cl->screen->authPasswdData) {
- 	    securityType = rfbSecTypeVncAuth;
-    }
+    securityType = determinePrimarySecurityType(cl);
 
     if (cl->protocolMajorVersion==3 && cl->protocolMinorVersion < 7)
     {
 	/* Make sure we use only RFB 3.3 compatible security types. */
+	if (channelSecurityHandlers) {
+	    rfbLog("VNC channel security enabled - RFB 3.3 client rejected\n");
+	    rfbClientConnFailed(cl, "Your viewer cannot handler required "
+				"security methods");
+	    return;
+	}
 	if (securityType == rfbSecTypeInvalid) {
 	    rfbLog("VNC authentication disabled - RFB 3.3 client rejected\n");
 	    rfbClientConnFailed(cl, "Your viewer cannot handle required "
@@ -318,9 +396,13 @@ rfbAuthNewClient(rfbClientPtr cl)
 	    return;
 	}
 	rfbSendSecurityType(cl, securityType);
+    } else if (channelSecurityHandlers) {
+	rfbLog("Send channel security type list\n");
+	rfbSendChannelSecurityTypeList(cl);
     } else {
 	/* Here it's ok when securityType is set to rfbSecTypeInvalid. */
-	rfbSendSecurityTypeList(cl, securityType);
+	rfbLog("Send channel security type 'none'\n");
+	rfbSendSecurityTypeList(cl, RFB_SECURITY_TAG_NONE);
     }
 }
 
@@ -334,6 +416,7 @@ rfbProcessClientSecurityType(rfbClientPtr cl)
     int n;
     uint8_t chosenType;
     rfbSecurityHandler* handler;
+    rfbSecurityHandler* handlerListHead;
     
     /* Read the security type. */
     n = rfbReadExact(cl, (char *)&chosenType, 1);
@@ -346,8 +429,17 @@ rfbProcessClientSecurityType(rfbClientPtr cl)
 	return;
     }
 
+    switch (cl->state) {
+    case RFB_CHANNEL_SECURITY_TYPE:
+        handlerListHead = channelSecurityHandlers;
+        break;
+    case RFB_SECURITY_TYPE:
+        handlerListHead = securityHandlers;
+        break;
+    }
+
     /* Make sure it was present in the list sent by the server. */
-    for (handler = securityHandlers; handler; handler = handler->next) {
+    for (handler = handlerListHead; handler; handler = handler->next) {
 	if (chosenType == handler->type) {
 	      rfbLog("rfbProcessClientSecurityType: executing handler for type %d\n", chosenType);
 	      handler->handler(cl);
diff --git a/src/libvncserver/rfbserver.c b/src/libvncserver/rfbserver.c
index dd0dabb4..19233f66 100644
--- a/src/libvncserver/rfbserver.c
+++ b/src/libvncserver/rfbserver.c
@@ -376,6 +376,10 @@ rfbNewTCPOrUDPClient(rfbScreenInfoPtr rfbScreen,
 
     cl->screen = rfbScreen;
     cl->sock = sock;
+    cl->readFromSocket = rfbDefaultReadFromSocket;
+    cl->peekAtSocket = rfbDefaultPeekAtSocket;
+    cl->hasPendingOnSocket = rfbDefaultHasPendingOnSocket;
+    cl->writeToSocket = rfbDefaultWriteToSocket;
     cl->viewOnly = FALSE;
     /* setup pseudo scaling */
     cl->scaledScreen = rfbScreen;
@@ -733,6 +737,7 @@ rfbProcessClientMessage(rfbClientPtr cl)
     case RFB_PROTOCOL_VERSION:
         rfbProcessClientProtocolVersion(cl);
         return;
+    case RFB_CHANNEL_SECURITY_TYPE:
     case RFB_SECURITY_TYPE:
         rfbProcessClientSecurityType(cl);
         return;
diff --git a/src/libvncserver/sockets.c b/src/libvncserver/sockets.c
index 6c87a2a1..3a4c6da7 100644
--- a/src/libvncserver/sockets.c
+++ b/src/libvncserver/sockets.c
@@ -101,6 +101,9 @@ int deny_severity=LOG_WARNING;
 int rfbMaxClientWait = 20000;   /* time (ms) after which we decide client has
                                    gone away - needed to stop us hanging */
 
+static rfbBool
+rfbHasPendingOnSocket(rfbClientPtr cl);
+
 static rfbBool
 rfbNewConnectionFromSock(rfbScreenInfoPtr rfbScreen, rfbSocket sock)
 {
@@ -364,16 +367,20 @@ rfbCheckFds(rfbScreenInfoPtr rfbScreen,long usec)
 	tv.tv_usec = usec;
 	nfds = select(rfbScreen->maxFd + 1, &fds, NULL, NULL /* &fds */, &tv);
 	if (nfds == 0) {
+            rfbBool hasPendingData = FALSE;
+
 	    /* timed out, check for async events */
             i = rfbGetClientIterator(rfbScreen);
             while((cl = rfbClientIteratorNext(i))) {
                 if (cl->onHold)
                     continue;
+                hasPendingData |= rfbHasPendingOnSocket(cl);
                 if (FD_ISSET(cl->sock, &(rfbScreen->allFds)))
                     rfbSendFileTransferChunk(cl);
             }
             rfbReleaseClientIterator(i);
-	    return result;
+            if (!hasPendingData)
+                return result;
 	}
 
 	if (nfds < 0) {
@@ -449,9 +456,11 @@ rfbCheckFds(rfbScreenInfoPtr rfbScreen,long usec)
 	    if (cl->onHold)
 		continue;
 
-            if (FD_ISSET(cl->sock, &(rfbScreen->allFds)))
+            if (rfbHasPendingOnSocket (cl) ||
+                FD_ISSET(cl->sock, &(rfbScreen->allFds)))
             {
-                if (FD_ISSET(cl->sock, &fds))
+                if (rfbHasPendingOnSocket (cl) ||
+                    FD_ISSET(cl->sock, &fds))
                 {
 #ifdef LIBVNCSERVER_WITH_WEBSOCKETS
                     do {
@@ -649,6 +658,30 @@ size_t fuzz_size;
 const uint8_t *fuzz_data;
 #endif
 
+int
+rfbDefaultReadFromSocket(rfbClientPtr cl, char *buf, int len)
+{
+    return read(cl->sock, buf, len);
+}
+
+static int
+rfbReadFromSocket(rfbClientPtr cl, char *buf, int len)
+{
+    return cl->readFromSocket(cl, buf, len);
+}
+
+rfbBool
+rfbDefaultHasPendingOnSocket(rfbClientPtr cl)
+{
+    return FALSE;
+}
+
+static rfbBool
+rfbHasPendingOnSocket(rfbClientPtr cl)
+{
+    return cl->hasPendingOnSocket(cl);
+}
+
 /*
  * ReadExact reads an exact number of bytes from a client.  Returns 1 if
  * those bytes have been read, 0 if the other end has closed, or -1 if an error
@@ -682,10 +715,10 @@ rfbReadExactTimeout(rfbClientPtr cl, char* buf, int len, int timeout)
         } else if (cl->sslctx) {
 	    n = rfbssl_read(cl, buf, len);
 	} else {
-            n = read(sock, buf, len);
+            n = rfbReadFromSocket(cl, buf, len);
         }
 #else
-        n = read(sock, buf, len);
+        n = rfbReadFromSocket(cl, buf, len);
 #endif
 
         if (n > 0) {
@@ -717,6 +750,10 @@ rfbReadExactTimeout(rfbClientPtr cl, char* buf, int len, int timeout)
 		    continue;
 	    }
 #endif
+
+            if (rfbHasPendingOnSocket(cl))
+                continue;
+
             FD_ZERO(&fds);
             FD_SET(sock, &fds);
             tv.tv_sec = timeout / 1000;
@@ -753,6 +790,18 @@ int rfbReadExact(rfbClientPtr cl,char* buf,int len)
     return(rfbReadExactTimeout(cl,buf,len,rfbMaxClientWait));
 }
 
+int
+rfbDefaultPeekAtSocket(rfbClientPtr cl, char *buf, int len)
+{
+    return recv(cl->sock, buf, len, MSG_PEEK);
+}
+
+int
+rfbPeekAtSocket(rfbClientPtr cl, char *buf, int len)
+{
+    return cl->peekAtSocket(cl, buf, len);
+}
+
 /*
  * PeekExact peeks at an exact number of bytes from a client.  Returns 1 if
  * those bytes have been read, 0 if the other end has closed, or -1 if an
@@ -785,7 +834,7 @@ rfbPeekExactTimeout(rfbClientPtr cl, char* buf, int len, int timeout)
 	    n = rfbssl_peek(cl, buf, len);
 	else
 #endif
-	    n = recv(sock, buf, len, MSG_PEEK);
+            n = rfbPeekAtSocket(cl, buf, len);
 
         if (n == len) {
 
@@ -841,6 +890,22 @@ rfbPeekExactTimeout(rfbClientPtr cl, char* buf, int len, int timeout)
     return 1;
 }
 
+int
+rfbDefaultWriteToSocket(rfbClientPtr cl,
+			const char *buf,
+			int len)
+{
+    return write(cl->sock, buf, len);
+}
+
+static int
+rfbWriteToSocket(rfbClientPtr cl,
+		 const char *buf,
+		 int len)
+{
+    return cl->writeToSocket(cl, buf, len);
+}
+
 /*
  * WriteExact writes an exact number of bytes to a client.  Returns 1 if
  * those bytes have been written, or -1 if an error occurred (errno is set to
@@ -905,7 +970,7 @@ rfbWriteExact(rfbClientPtr cl,
 	    n = rfbssl_write(cl, buf, len);
 	else
 #endif
-	    n = write(sock, buf, len);
+	    n = rfbWriteToSocket(cl, buf, len);
 
         if (n > 0) {