TcpClient.Connected Property

The Connected property gets the connection state of the Client socket as of the last I/O operation. When it returns false, the Client socket was either never connected, or is no longer connected.

Because the Connected property only reflects the state of the connection as of the most recent operation, you should attempt to send or receive a message to determine the current state. After the message send fails, this property no longer returns true. Note that this behavior is by design. You cannot reliably test the state of the connection because, in the time between the test and a send/receive, the connection could have been lost. Your code should assume the socket is connected, and gracefully handle failed transmissions.

The following code example connects to a remote endpoint and then verifies the connection.

static void GetConnected()
{
    // Find out whether the socket is connected to the remote  
    // host.
    Console.WriteLine("Connected value is {0}", t.Connected);
}

.NET Framework

.NET Framework Client Profile

Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference