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SocketType Enumeration

Specifies the type of socket that an instance of the Socket class represents.

Namespace:  System.Net.Sockets
Assembly:  System (in System.dll)

Public Enumeration SocketType

Member nameDescription
StreamSupports reliable, two-way, connection-based byte streams without the duplication of data and without preservation of boundaries. A Socket of this type communicates with a single peer and requires a remote host connection before communication can begin. Stream uses the Transmission Control Protocol (Tcp) ProtocolType and the InterNetwork AddressFamily.
DgramSupports datagrams, which are connectionless, unreliable messages of a fixed (typically small) maximum length. Messages might be lost or duplicated and might arrive out of order. A Socket of type Dgram requires no connection prior to sending and receiving data, and can communicate with multiple peers. Dgram uses the Datagram Protocol (Udp) and the InterNetwork AddressFamily.
RawSupports access to the underlying transport protocol. Using the SocketType Raw, you can communicate using protocols like Internet Control Message Protocol (Icmp) and Internet Group Management Protocol (Igmp). Your application must provide a complete IP header when sending. Received datagrams return with the IP header and options intact.
RdmSupports connectionless, message-oriented, reliably delivered messages, and preserves message boundaries in data. Rdm (Reliably Delivered Messages) messages arrive unduplicated and in order. Furthermore, the sender is notified if messages are lost. If you initialize a Socket using Rdm, you do not require a remote host connection before sending and receiving data. With Rdm, you can communicate with multiple peers.
SeqpacketProvides connection-oriented and reliable two-way transfer of ordered byte streams across a network. Seqpacket does not duplicate data, and it preserves boundaries within the data stream. A Socket of type Seqpacket communicates with a single peer and requires a remote host connection before communication can begin.
UnknownSpecifies an unknown Socket type.

Before a Socket can send and receive data, it must first be created using an AddressFamily, a SocketType, and a ProtocolType. The SocketType enumeration provides several options for defining the type of Socket that you intend to open.


SocketType will sometimes implicitly indicate which ProtocolType will be used within an AddressFamily. For example when the SocketType is Dgram, the ProtocolType is always Udp.When the SocketType is Stream, the ProtocolType is always Tcp. If you try to create a Socket with an incompatible combination, Socket will throw a SocketException.

The following example uses the Stream enumerated member as a parameter to the Socket constructor.

'Creates the Socket for sending data over TCP.
Dim s As New Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp)

' Connects to host using IPEndPoint.
If Not s.Connected Then
   strRetPage = "Unable to connect to host"
End If
' Use the SelectWrite enumeration to obtain Socket status.
If s.Poll(- 1, SelectMode.SelectWrite) Then
   Console.WriteLine("This Socket is writable.")
   If s.Poll(- 1, SelectMode.SelectRead) Then
      Console.WriteLine(("This Socket is readable. "))
      If s.Poll(- 1, SelectMode.SelectError) Then
         Console.WriteLine("This Socket has an error.")
      End If
   End If 
End If 

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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