diff --git a/.gitmodules b/.gitmodules
index 8232a78..34b096c 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,7 +1,7 @@
 [submodule "kasmweb"]
 	path = kasmweb
 	url = https://github.com/kasmtech/noVNC.git
-	branch = master
+	branch = feature/VNC-275_server_idle_timeout
 [submodule "kasmvnc-functional-tests"]
 	path = kasmvnc-functional-tests
 	url = git@gitlab.com:kasm-technologies/internal/kasmvnc-functional-tests.git
diff --git a/common/rfb/ConnParams.cxx b/common/rfb/ConnParams.cxx
index 31a0984..6624849 100644
--- a/common/rfb/ConnParams.cxx
+++ b/common/rfb/ConnParams.cxx
@@ -59,6 +59,7 @@ ConnParams::ConnParams()
     supportsWEBP(false), supportsQOI(false),
     supportsSetDesktopSize(false), supportsFence(false),
     supportsContinuousUpdates(false), supportsExtendedClipboard(false),
+    supportsDisconnectNotify(false),
     supportsUdp(false),
     compressLevel(2), qualityLevel(-1), fineQualityLevel(-1),
     subsampling(subsampleUndefined), name_(0), cursorPos_(0, 0), verStrPos(0),
@@ -147,6 +148,7 @@ void ConnParams::setEncodings(int nEncodings, const rdr::S32* encodings)
   supportsQEMUKeyEvent = false;
   supportsWEBP = false;
   supportsQOI = false;
+  supportsDisconnectNotify = false;
   compressLevel = -1;
   qualityLevel = -1;
   fineQualityLevel = -1;
@@ -215,6 +217,10 @@ void ConnParams::setEncodings(int nEncodings, const rdr::S32* encodings)
       supportsQOI = true;
       clientparlog("qoi", true);
       break;
+    case pseudoEncodingKasmDisconnectNotify:
+      supportsDisconnectNotify = true;
+      clientparlog("disconnectNotify", true);
+      break;
     case pseudoEncodingFence:
       supportsFence = true;
       clientparlog("fence", true);
diff --git a/common/rfb/ConnParams.h b/common/rfb/ConnParams.h
index 0f25055..96ce5cd 100644
--- a/common/rfb/ConnParams.h
+++ b/common/rfb/ConnParams.h
@@ -117,6 +117,7 @@ namespace rfb {
     bool supportsFence;
     bool supportsContinuousUpdates;
     bool supportsExtendedClipboard;
+    bool supportsDisconnectNotify;
 
     bool supportsUdp;
 
diff --git a/common/rfb/SMsgHandler.cxx b/common/rfb/SMsgHandler.cxx
index ac9e588..23cd5fc 100644
--- a/common/rfb/SMsgHandler.cxx
+++ b/common/rfb/SMsgHandler.cxx
@@ -104,3 +104,7 @@ void SMsgHandler::setDesktopSize(int fb_width, int fb_height,
   cp.height = fb_height;
   cp.screenLayout = layout;
 }
+
+void SMsgHandler::keepAlive()
+{
+}
diff --git a/common/rfb/SMsgHandler.h b/common/rfb/SMsgHandler.h
index 8856b9f..b8a6e7f 100644
--- a/common/rfb/SMsgHandler.h
+++ b/common/rfb/SMsgHandler.h
@@ -61,6 +61,7 @@ namespace rfb {
 
     virtual void sendStats(const bool toClient = true) = 0;
     virtual void handleFrameStats(rdr::U32 all, rdr::U32 render) = 0;
+    virtual void keepAlive();
 
     virtual bool canChangeKasmSettings() const = 0;
 
diff --git a/common/rfb/SMsgReader.cxx b/common/rfb/SMsgReader.cxx
index 06d7953..933b1d8 100644
--- a/common/rfb/SMsgReader.cxx
+++ b/common/rfb/SMsgReader.cxx
@@ -106,6 +106,9 @@ void SMsgReader::readMsg()
   case msgTypeUnixRelay:
     readUnixRelay();
     break;
+  case msgTypeKeepAlive:
+    readKeepAlive();
+    break;
   default:
     fprintf(stderr, "unknown message type %d\n", msgType);
     throw Exception("unknown message type");
@@ -319,6 +322,11 @@ void SMsgReader::readFrameStats()
   handler->handleFrameStats(all, render);
 }
 
+void SMsgReader::readKeepAlive()
+{
+  handler->keepAlive();
+}
+
 void SMsgReader::readQEMUMessage()
 {
   int subType = is->readU8();
diff --git a/common/rfb/SMsgReader.h b/common/rfb/SMsgReader.h
index 60d49c0..77af609 100644
--- a/common/rfb/SMsgReader.h
+++ b/common/rfb/SMsgReader.h
@@ -59,6 +59,7 @@ namespace rfb {
     void readRequestStats();
     void readFrameStats();
     void readBinaryClipboard();
+    void readKeepAlive();
 
     void readQEMUMessage();
     void readQEMUKeyEvent();
diff --git a/common/rfb/SMsgWriter.cxx b/common/rfb/SMsgWriter.cxx
index eebb394..0282a17 100644
--- a/common/rfb/SMsgWriter.cxx
+++ b/common/rfb/SMsgWriter.cxx
@@ -791,3 +791,20 @@ void SMsgWriter::writeUserLeftSession(const std::string& username)
   os->writeString(username.c_str());
   endMsg();
 }
+
+void SMsgWriter::writeDisconnectNotify(bool graceful, const char *reason)
+{
+  if (!cp->supportsDisconnectNotify)
+    return;
+
+  const char *msg = reason ? reason : "";
+  size_t len = strlen(msg);
+
+  startMsg(msgTypeServerDisconnect);
+  os->writeU8(graceful ? 1 : 0);
+  os->pad(3);
+  os->writeU32(len);
+  if (len > 0)
+    os->writeBytes(msg, len);
+  endMsg();
+}
diff --git a/common/rfb/SMsgWriter.h b/common/rfb/SMsgWriter.h
index 3a424bf..646c51a 100644
--- a/common/rfb/SMsgWriter.h
+++ b/common/rfb/SMsgWriter.h
@@ -135,6 +135,7 @@ namespace rfb {
 
     void writeUserJoinedSession(const std::string& username);
     void writeUserLeftSession(const std::string& username);
+    void writeDisconnectNotify(bool graceful, const char *reason);
 
   protected:
     void startMsg(int type);
diff --git a/common/rfb/VNCSConnectionST.cxx b/common/rfb/VNCSConnectionST.cxx
index cf3af0b..c234fe9 100644
--- a/common/rfb/VNCSConnectionST.cxx
+++ b/common/rfb/VNCSConnectionST.cxx
@@ -49,6 +49,10 @@ static LogWriter vlog("VNCSConnST");
 
 static Cursor emptyCursor(0, 0, Point(0, 0), NULL);
 
+namespace {
+const rdr::U32 CLIENT_KEEPALIVE_KEYSYM = 1;
+}
+
 extern rfb::BoolParameter disablebasicauth;
 
 extern "C" char unixrelaynames[MAX_UNIX_RELAYS][MAX_UNIX_RELAY_NAME_LEN];
@@ -557,6 +561,13 @@ int VNCSConnectionST::checkIdleTimeout()
     return secsToMillis(idleTimeout);
   }
   if (timeLeft <= 0) {
+    if (cp.supportsDisconnectNotify) {
+      try {
+        writer()->writeDisconnectNotify(true, "Idle timeout");
+      } catch (rdr::Exception& e) {
+        vlog.debug("Failed to send disconnect notice: %s", e.str());
+      }
+    }
     close("Idle timeout");
     return 0;
   }
@@ -861,6 +872,10 @@ public:
 void VNCSConnectionST::keyEvent(rdr::U32 keysym, rdr::U32 keycode, bool down) {
   rdr::U32 lookup;
 
+  if (keycode == 0 && keysym == CLIENT_KEEPALIVE_KEYSYM) {
+    return;
+  }
+
   lastEventTime = time(0);
   server->lastUserInputTime = lastEventTime;
   if (!(accessRights & AccessKeyEvents)) return;
@@ -1699,6 +1714,11 @@ void VNCSConnectionST::handleFrameStats(rdr::U32 all, rdr::U32 render)
   frameTracking = false;
 }
 
+void VNCSConnectionST::keepAlive()
+{
+  // Keepalive traffic should not influence idle disconnect timers.
+}
+
 // setCursor() is called whenever the cursor has changed shape or pixel format.
 // If the client supports local cursor then it will arrange for the cursor to
 // be sent to the client.
diff --git a/common/rfb/VNCSConnectionST.h b/common/rfb/VNCSConnectionST.h
index 6d8068c..4148494 100644
--- a/common/rfb/VNCSConnectionST.h
+++ b/common/rfb/VNCSConnectionST.h
@@ -172,6 +172,7 @@ namespace rfb {
 
     virtual void sendStats(const bool toClient = true);
     virtual void handleFrameStats(rdr::U32 all, rdr::U32 render);
+    virtual void keepAlive();
 
     bool is_owner() const {
       bool read, write, owner;
diff --git a/common/rfb/encodings.h b/common/rfb/encodings.h
index dbc4dc7..7fa6fa3 100644
--- a/common/rfb/encodings.h
+++ b/common/rfb/encodings.h
@@ -86,6 +86,7 @@ namespace rfb {
   const int pseudoEncodingVideoOutTimeLevel1 = -1986;
   const int pseudoEncodingVideoOutTimeLevel100 = -1887;
   const int pseudoEncodingQOI = -1886;
+  const int pseudoEncodingKasmDisconnectNotify = -1885;
 
   // VMware-specific
   const int pseudoEncodingVMwareCursor = 0x574d5664;
diff --git a/common/rfb/msgTypes.h b/common/rfb/msgTypes.h
index 9098b33..e3932ad 100644
--- a/common/rfb/msgTypes.h
+++ b/common/rfb/msgTypes.h
@@ -35,6 +35,8 @@ namespace rfb {
   const int msgTypeUpgradeToUdp = 181;
   const int msgTypeSubscribeUnixRelay = 182;
   const int msgTypeUnixRelay = 183;
+  const int msgTypeKeepAlive = 184;
+  const int msgTypeServerDisconnect = 185;
 
   const int msgTypeServerFence = 248;
   const int msgTypeUserAddedToSession = 253;
@@ -61,6 +63,8 @@ namespace rfb {
   //const int msgTypeUpgradeToUdp = 181;
   //const int msgTypeSubscribeUnixRelay = 182;
   //const int msgTypeUnixRelay = 183;
+  //const int msgTypeKeepAlive = 184;
+  //const int msgTypeServerDisconnect = 185;
 
   const int msgTypeClientFence = 248;
 
diff --git a/kasmweb b/kasmweb
index da6b8f3..0dab999 160000
--- a/kasmweb
+++ b/kasmweb
@@ -1 +1 @@
-Subproject commit da6b8f3cfbed05891380f33aa4ca541c99d1f4c6
+Subproject commit 0dab9997d98ff5046682f15e1632af5ecf72f180