diff --git a/CMakeLists.txt b/CMakeLists.txt
index b632d5f..ff729d5 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -14,8 +14,8 @@ cmake_minimum_required(VERSION 3.2 FATAL_ERROR)
 
 # project name
 project(amqpcpp)
-set (VERSION_MAJOR 3)
-set (VERSION_MINOR 2)
+set (VERSION_MAJOR 4)
+set (VERSION_MINOR 0)
 set (VERSION_PATCH 0)
 set (SO_VERSION ${VERSION_MAJOR}.${VERSION_MINOR})
 
diff --git a/Makefile b/Makefile
index a5a9ca6..0ea9e6e 100644
--- a/Makefile
+++ b/Makefile
@@ -2,8 +2,8 @@ PREFIX                  ?= /usr
 INCLUDE_DIR             = ${PREFIX}/include
 LIBRARY_DIR             = ${PREFIX}/lib
 export LIBRARY_NAME		= amqpcpp
-export SONAME			= 3.2
-export VERSION			= 3.2.0
+export SONAME			= 4.0
+export VERSION			= 4.0.0
 
 all:
 		$(MAKE) -C src all
diff --git a/include/amqpcpp/linux_tcp/tcpconnection.h b/include/amqpcpp/linux_tcp/tcpconnection.h
index dd1aabd..2040793 100644
--- a/include/amqpcpp/linux_tcp/tcpconnection.h
+++ b/include/amqpcpp/linux_tcp/tcpconnection.h
@@ -238,6 +238,8 @@ public:
     
     /**
      *  Is the connection in a usable state / not yet closed or being closed
+     *  When a connection is usable, you can send further commands over it. When it is
+     *  unusable, it may still be connected and finished queued commands.
      *  @return bool
      */
     bool usable() const
@@ -245,6 +247,12 @@ public:
         return _connection.usable();
     }
     
+    /**
+     *  Is the connection closed and full dead? The entire TCP connection has been discarded.
+     *  @return bool
+     */
+    bool closed() const;
+    
     /**
      *  The max frame size. Useful if you set up a buffer to parse incoming data: it does not have to exceed this size.
      *  @return uint32_t
diff --git a/src/linux_tcp/tcpclosed.h b/src/linux_tcp/tcpclosed.h
index 90d5fd6..e33d4f8 100644
--- a/src/linux_tcp/tcpclosed.h
+++ b/src/linux_tcp/tcpclosed.h
@@ -41,6 +41,12 @@ public:
      *  Destructor
      */
     virtual ~TcpClosed() noexcept = default;
+
+    /**
+     *  Is this a closed / dead state?
+     *  @return bool
+     */
+    virtual bool closed() const override { return true; }
 };
     
 /**
diff --git a/src/linux_tcp/tcpconnection.cpp b/src/linux_tcp/tcpconnection.cpp
index d01792c..f4763d9 100644
--- a/src/linux_tcp/tcpconnection.cpp
+++ b/src/linux_tcp/tcpconnection.cpp
@@ -57,6 +57,15 @@ std::size_t TcpConnection::queued() const
     return _state->queued();
 }
 
+/**
+ *  Is the connection closed and full dead? The entire TCP connection has been discarded.
+ *  @return bool
+ */
+bool TcpConnection::closed() const
+{
+    return _state->closed();
+}
+
 /**
  *  Process the TCP connection
  *  This method should be called when the filedescriptor that is registered
diff --git a/src/linux_tcp/tcpstate.h b/src/linux_tcp/tcpstate.h
index 190091c..4699498 100644
--- a/src/linux_tcp/tcpstate.h
+++ b/src/linux_tcp/tcpstate.h
@@ -62,6 +62,12 @@ public:
      *  @return size_t
      */
     virtual std::size_t queued() const { return 0; }
+    
+    /**
+     *  Is this a closed / dead state?
+     *  @return bool
+     */
+    virtual bool closed() const { return false; }
 
     /**
      *  Process the filedescriptor in the object