diff --git a/src/SuperSocket.Command/CommandMiddleware.cs b/src/SuperSocket.Command/CommandMiddleware.cs
index 9b90717e9..5451dc827 100644
--- a/src/SuperSocket.Command/CommandMiddleware.cs
+++ b/src/SuperSocket.Command/CommandMiddleware.cs
@@ -45,6 +45,8 @@ public class CommandMiddleware<TKey, TNetPackageInfo, TPackageInfo> : Middleware
     {
         private Dictionary<TKey, ICommandSet> _commands;
 
+        private Func<IAppSession, TPackageInfo, CancellationToken, ValueTask> _unknownPackageHandler;
+
         private ILogger _logger;
 
         protected IPackageMapper<TNetPackageInfo, TPackageInfo> PackageMapper { get; private set; }    
@@ -136,6 +138,18 @@ public CommandMiddleware(IServiceProvider serviceProvider, IOptions<CommandOptio
             _commands = commandDict;
             
             PackageMapper = packageMapper != null ? packageMapper : CreatePackageMapper(serviceProvider);
+
+            var unknownPackageHandler = commandOptions.Value.UnknownPackageHandler;
+
+            if (unknownPackageHandler != null)
+            {
+                _unknownPackageHandler = unknownPackageHandler as Func<IAppSession, TPackageInfo, CancellationToken, ValueTask>;
+
+                if (_unknownPackageHandler == null)
+                {
+                    _logger.LogError($"{nameof(commandOptions.Value.UnknownPackageHandler)} was registered with incorrectly. The expected typew is {typeof(Func<IAppSession, TPackageInfo, ValueTask>).Name}.");
+                }
+            }            
         }
 
         private void RegisterCommandInterfaces(List<CommandTypeInfo> commandInterfaces, List<ICommandSetFactory> commandSetFactories, IServiceProvider serviceProvider, Type sessionType, Type packageType, bool wrapRequired = false)
@@ -200,6 +214,13 @@ protected virtual async ValueTask HandlePackage(IAppSession session, TPackageInf
         {
             if (!_commands.TryGetValue(package.Key, out ICommandSet commandSet))
             {
+                var unknownPackageHandler = _unknownPackageHandler;
+
+                if (unknownPackageHandler != null)
+                {
+                    await unknownPackageHandler.Invoke(session, package, cancellationToken);
+                }
+
                 return;
             }
 
diff --git a/src/SuperSocket.Command/CommandOptions.cs b/src/SuperSocket.Command/CommandOptions.cs
index 1d759292c..857a51407 100644
--- a/src/SuperSocket.Command/CommandOptions.cs
+++ b/src/SuperSocket.Command/CommandOptions.cs
@@ -2,6 +2,10 @@
 using System.Linq;
 using System.Collections.Generic;
 using System.Reflection;
+using System.Threading.Tasks;
+using SuperSocket.ProtoBase;
+using SuperSocket.Server.Abstractions.Session;
+using System.Threading;
 
 namespace SuperSocket.Command
 {
@@ -13,6 +17,13 @@ public CommandOptions()
             _globalCommandFilterTypes = new List<Type>();
         }
 
+        internal object UnknownPackageHandler { get; private set; }
+
+        public void RegisterUnknownPackageHandler<TPackageInfo>(Func<IAppSession, TPackageInfo, CancellationToken, ValueTask> unknownPackageHandler)
+        {
+            UnknownPackageHandler = unknownPackageHandler;
+        }
+
         public CommandAssemblyConfig[] Assemblies { get; set; }
 
         public List<ICommandSource> CommandSources { get; set; }
diff --git a/test/SuperSocket.Tests/CommandTest.cs b/test/SuperSocket.Tests/CommandTest.cs
index 8f0a61577..229b292ba 100644
--- a/test/SuperSocket.Tests/CommandTest.cs
+++ b/test/SuperSocket.Tests/CommandTest.cs
@@ -89,6 +89,57 @@ public async Task TestCommands(Type hostConfiguratorType)
             }
         }
 
+        [Theory]
+        [InlineData(typeof(RegularHostConfigurator))]
+        [InlineData(typeof(SecureHostConfigurator))]
+        public async Task TestUnknownCommands(Type hostConfiguratorType)
+        {
+            var hostConfigurator = CreateObject<IHostConfigurator>(hostConfiguratorType);
+            using (var server = CreateSocketServerBuilder<StringPackageInfo, CommandLinePipelineFilter>(hostConfigurator)
+                .UseCommand(commandOptions =>
+                {
+                    // register commands one by one
+                    commandOptions.AddCommand<ADD>();
+                    commandOptions.RegisterUnknownPackageHandler<StringPackageInfo>(async (session, package, cancellationToken) =>
+                    {
+                        await session.SendAsync(Encoding.UTF8.GetBytes("X\r\n"));
+                    });
+
+                    // register all commands in one assembly
+                    //commandOptions.AddCommandAssembly(typeof(SUB).GetTypeInfo().Assembly);
+                })
+                .BuildAsServer())
+            {
+
+                Assert.Equal("TestServer", server.Name);
+
+                Assert.True(await server.StartAsync());
+                OutputHelper.WriteLine("Server started.");
+
+
+                var client = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
+                await client.ConnectAsync(hostConfigurator.GetServerEndPoint());
+                OutputHelper.WriteLine("Connected.");
+
+                using (var stream = await hostConfigurator.GetClientStream(client))
+                using (var streamReader = new StreamReader(stream, Utf8Encoding, true))
+                using (var streamWriter = new StreamWriter(stream, Utf8Encoding, 1024 * 1024 * 4))
+                {
+                    await streamWriter.WriteAsync("ADD 1 2 3\r\n");
+                    await streamWriter.FlushAsync();
+                    var line = await streamReader.ReadLineAsync();
+                    Assert.Equal("6", line);
+
+                    await streamWriter.WriteAsync("MULT 2 5\r\n");
+                    await streamWriter.FlushAsync();
+                    line = await streamReader.ReadLineAsync();
+                    Assert.Equal("X", line);
+                }
+
+                await server.StopAsync();
+            }
+        }
+
         [Theory]
         [InlineData(typeof(RegularHostConfigurator))]
         [InlineData(typeof(SecureHostConfigurator))]