diff --git a/sshd-core/src/main/java/org/apache/sshd/common/session/helpers/AbstractSession.java b/sshd-core/src/main/java/org/apache/sshd/common/session/helpers/AbstractSession.java
index 4468276c7..0553e279f 100644
--- a/sshd-core/src/main/java/org/apache/sshd/common/session/helpers/AbstractSession.java
+++ b/sshd-core/src/main/java/org/apache/sshd/common/session/helpers/AbstractSession.java
@@ -175,6 +175,8 @@ public abstract class AbstractSession extends SessionHelper {
     protected final Object encodeLock = new Object();
     protected final Object decodeLock = new Object();
     protected final Object requestLock = new Object();
+    // There are some cases where we need to know the sequence number
+    protected final AtomicLong requestSeqo = new AtomicLong(-1);
 
     /*
      * Rekeying
@@ -980,6 +982,7 @@ public Buffer request(String request, Buffer buffer, long timeout, TimeUnit unit
                     }
 
                     result = requestResult.getAndSet(null);
+                    requestSeqo.set(-1);
                 }
             } catch (InterruptedException e) {
                 throw (InterruptedIOException) new InterruptedIOException(
@@ -1069,6 +1072,11 @@ protected Buffer encode(Buffer buffer) throws IOException {
             // Check that the packet has some free space for the header
             int curPos = buffer.rpos();
             int cmd = buffer.rawByte(curPos) & 0xFF;  // usually the 1st byte is an SSH opcode
+
+            if (cmd == SshConstants.SSH_MSG_GLOBAL_REQUEST) {
+                requestSeqo.set(seqo);
+            }
+
             if (curPos < SshConstants.SSH_PACKET_HEADER_LEN) {
                 log.warn("encode({}) command={}[{}] performance cost: available buffer packet header length ({}) below min. required ({})",
                      this, cmd, SshConstants.getCommandMessageName(cmd),
@@ -1792,6 +1800,15 @@ protected void requestSuccess(Buffer buffer) throws Exception {
      * @throws Exception If failed to handle the message
      */
     protected void requestFailure(Buffer buffer) throws Exception {
+        signalRequestFailure();
+    }
+
+    /**
+     * Marks the current pending global request result as failed
+     *
+     * @throws Exception If failed to signal
+     */
+    protected void signalRequestFailure() throws Exception {
         synchronized (requestResult) {
             requestResult.set(GenericUtils.NULL);
             resetIdleTimeout();
@@ -1799,6 +1816,24 @@ protected void requestFailure(Buffer buffer) throws Exception {
         }
     }
 
+    @Override
+    protected void doHandleUnimplemented(Buffer buffer) throws Exception {
+        // Some servers do respond to requests with the SSH_MSG_UNIMPLEMENTED
+        // message instead of SSH_MSG_REQUEST_FAILURE, so deal with it
+        if (requestSeqo.get() >= 0) {
+            synchronized (requestResult) {
+                int rpos = buffer.rpos();
+                long seq = buffer.getUInt();
+                if (requestSeqo.get() == seq) {
+                    signalRequestFailure();
+                    return;
+                }
+                buffer.rpos(rpos);
+            }
+        }
+        super.doHandleUnimplemented(buffer);
+    }
+
     @Override
     public void addSessionListener(SessionListener listener) {
         SessionListener.validateListener(listener);
diff --git a/sshd-core/src/main/java/org/apache/sshd/common/session/helpers/SessionHelper.java b/sshd-core/src/main/java/org/apache/sshd/common/session/helpers/SessionHelper.java
index 6003372c6..388da96a0 100644
--- a/sshd-core/src/main/java/org/apache/sshd/common/session/helpers/SessionHelper.java
+++ b/sshd-core/src/main/java/org/apache/sshd/common/session/helpers/SessionHelper.java
@@ -431,6 +431,10 @@ protected void handleUnimplemented(Buffer buffer) throws Exception {
         }
         resetIdleTimeout();
 
+        doHandleUnimplemented(buffer);
+    }
+
+    protected void doHandleUnimplemented(Buffer buffer) throws Exception {
         ReservedSessionMessagesHandler handler = resolveReservedSessionMessagesHandler();
         handler.handleUnimplementedMessage(this, SshConstants.SSH_MSG_UNIMPLEMENTED, buffer);
     }
diff --git a/sshd-core/src/test/java/org/apache/sshd/KeepAliveTest.java b/sshd-core/src/test/java/org/apache/sshd/KeepAliveTest.java
index efba1aed3..457f3790d 100644
--- a/sshd-core/src/test/java/org/apache/sshd/KeepAliveTest.java
+++ b/sshd-core/src/test/java/org/apache/sshd/KeepAliveTest.java
@@ -20,6 +20,7 @@
 
 import java.io.ByteArrayOutputStream;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.EnumSet;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
@@ -32,6 +33,9 @@
 import org.apache.sshd.common.FactoryManager;
 import org.apache.sshd.common.PropertyResolverUtils;
 import org.apache.sshd.common.channel.Channel;
+import org.apache.sshd.common.session.ConnectionService;
+import org.apache.sshd.common.session.helpers.AbstractConnectionServiceRequestHandler;
+import org.apache.sshd.common.util.buffer.Buffer;
 import org.apache.sshd.server.SshServer;
 import org.apache.sshd.server.channel.ChannelSession;
 import org.apache.sshd.server.command.Command;
@@ -107,6 +111,35 @@ public void tearDown() {
             client, ClientFactoryManager.HEARTBEAT_INTERVAL, ClientFactoryManager.DEFAULT_HEARTBEAT_INTERVAL);
     }
 
+    @Test
+    public void testSshd968() throws Exception {
+        sshd.setGlobalRequestHandlers(Collections.singletonList(new AbstractConnectionServiceRequestHandler() {
+            @Override
+            public Result process(ConnectionService connectionService, String request, boolean wantReply, Buffer buffer) throws Exception {
+                connectionService.process(255, buffer);
+                return Result.Replied;
+            }
+        }));
+
+        PropertyResolverUtils.updateProperty(client, ClientFactoryManager.HEARTBEAT_INTERVAL, HEARTBEAT);
+        PropertyResolverUtils.updateProperty(client, ClientFactoryManager.HEARTBEAT_REPLY_WAIT, 5000L);
+        try (ClientSession session = client.connect(getCurrentTestName(), TEST_LOCALHOST, port)
+                .verify(7L, TimeUnit.SECONDS)
+                .getSession()) {
+            session.addPasswordIdentity(getCurrentTestName());
+            session.auth().verify(5L, TimeUnit.SECONDS);
+
+            try (ClientChannel channel = session.createChannel(Channel.CHANNEL_SHELL)) {
+                long waitStart = System.currentTimeMillis();
+                Collection<ClientChannelEvent> result =
+                        channel.waitFor(EnumSet.of(ClientChannelEvent.CLOSED), WAIT);
+                long waitEnd = System.currentTimeMillis();
+                assertTrue("Wrong channel state after wait of " + (waitEnd - waitStart) + " ms: " + result,
+                        result.contains(ClientChannelEvent.TIMEOUT));
+            }
+        }
+    }
+
     @Test
     public void testIdleClient() throws Exception {
         try (ClientSession session = client.connect(getCurrentTestName(), TEST_LOCALHOST, port)