Which Pid Listens on a Given Port in C#

Which PID listens on a given port in c#

from win XP SP2 onwards you can P/Invoke to GetExtendedTcpTable

Using This person's kind work to flesh out the signature (the PInvoke.net spec is incomplete) here is a (rough and poor at error checking) example

using System;
using System.Runtime.InteropServices;

public enum TCP_TABLE_CLASS : int
{
    TCP_TABLE_BASIC_LISTENER,
    TCP_TABLE_BASIC_CONNECTIONS,
    TCP_TABLE_BASIC_ALL,
    TCP_TABLE_OWNER_PID_LISTENER,
    TCP_TABLE_OWNER_PID_CONNECTIONS,
    TCP_TABLE_OWNER_PID_ALL,
    TCP_TABLE_OWNER_MODULE_LISTENER,
    TCP_TABLE_OWNER_MODULE_CONNECTIONS,
    TCP_TABLE_OWNER_MODULE_ALL
} 

[StructLayout(LayoutKind.Sequential)]
public struct MIB_TCPROW_OWNER_PID
{
    public uint state;
    public uint localAddr;
    public byte localPort1;
    public byte localPort2;
    public byte localPort3;
    public byte localPort4;
    public uint remoteAddr;
    public byte remotePort1;
    public byte remotePort2;
    public byte remotePort3;
    public byte remotePort4;
    public int owningPid;

    public ushort LocalPort
{
        get
        {
            return BitConverter.ToUInt16(
                new byte[2] { localPort2, localPort1}, 0);
        }
    }

    public ushort RemotePort
    {
        get
        {
            return BitConverter.ToUInt16(
                new byte[2] { remotePort2, remotePort1}, 0);
        }
    }
}

[StructLayout(LayoutKind.Sequential)]
public struct MIB_TCPTABLE_OWNER_PID
{
    public uint dwNumEntries;
    MIB_TCPROW_OWNER_PID table;
}

[DllImport("iphlpapi.dll", SetLastError=true)]
static extern uint GetExtendedTcpTable(IntPtr pTcpTable, 
    ref int dwOutBufLen, 
    bool sort, 
    int ipVersion, 
    TCP_TABLE_CLASS tblClass,
    int reserved);

public static MIB_TCPROW_OWNER_PID[] GetAllTcpConnections()
{
    MIB_TCPROW_OWNER_PID[] tTable;
    int AF_INET = 2;    // IP_v4
    int buffSize = 0;

    // how much memory do we need?
    uint ret = GetExtendedTcpTable(IntPtr.Zero, 
        ref buffSize, 
        true, 
        AF_INET, 
        TCP_TABLE_CLASS.TCP_TABLE_OWNER_PID_ALL,
        0);        
    if (ret != 0 && ret != 122) // 122 insufficient buffer size
        throw new Exception("bad ret on check " + ret);
    IntPtr buffTable = Marshal.AllocHGlobal(buffSize);

    try
    {
        ret = GetExtendedTcpTable(buffTable, 
            ref buffSize, 
            true, 
            AF_INET, 
            TCP_TABLE_CLASS.TCP_TABLE_OWNER_PID_ALL, 
            0);
        if (ret != 0)
            throw new Exception("bad ret "+ ret);        

        // get the number of entries in the table
        MIB_TCPTABLE_OWNER_PID tab = 
            (MIB_TCPTABLE_OWNER_PID)Marshal.PtrToStructure(
                buffTable, 
                typeof(MIB_TCPTABLE_OWNER_PID));
         IntPtr rowPtr = (IntPtr)((long)buffTable + 
             Marshal.SizeOf(tab.dwNumEntries));
        tTable = new MIB_TCPROW_OWNER_PID[tab.dwNumEntries];

        for (int i = 0; i < tab.dwNumEntries; i++)
        {
            MIB_TCPROW_OWNER_PID tcpRow = (MIB_TCPROW_OWNER_PID)Marshal
                .PtrToStructure(rowPtr, typeof(MIB_TCPROW_OWNER_PID));
            tTable[i] = tcpRow;
            // next entry
            rowPtr = (IntPtr)((long)rowPtr + Marshal.SizeOf(tcpRow));   
        }
    }
    finally
    {
        // Free the Memory
        Marshal.FreeHGlobal(buffTable);
    }
    return tTable;
}

Why is WCF service listening as PID 4 (SYSTEM) and not as the PID of the process hosting it?

The Web API uses HTTP not TCP as its transport. By default only an administrator is allowed to start listening on HTTP endpoints. If you want another user to do so you need to use netsh on Windows 7/2008 or httpcfg on Windows XP/2003.

netsh http add urlacl url=http://+:80/MyUri user=DOMAIN\user

See Configuring HTTP and HTTPS

C# find process id (pid) of client making an UDP/TCP call

you can try this

netstat -a -n -o | find "1688"

You will get the exact output of the process

 UDP    10.4.112.77:55866      *:*                                    1688
 UDP    127.0.0.1:1900         *:*                                    1688
 UDP    127.0.0.1:55868        *:*                                    1688

Try this for complete process id port and process name.

1. Open a command prompt window (as Administrator) From "Start\Search box" Enter "cmd" then right-click on "cmd.exe" and select "Run as Administrator"
2. Enter: netstat -abno
3. Find the Port that you are listening on under "Local Address"
4. Look at the process name directly under that.

you can collect the information and then the parse the output

this one stack link might be helping you.
Which PID listens on a given port in c#

How to determine tcp port used by Windows process in C#

Except for PID, take a look this:

IPGlobalProperties ipProperties = IPGlobalProperties.GetIPGlobalProperties();

IPEndPoint[] endPoints = ipProperties.GetActiveTcpListeners();
TcpConnectionInformation[] tcpConnections = 
    ipProperties.GetActiveTcpConnections();

foreach (TcpConnectionInformation info in tcpConnections)
{
    Console.WriteLine("Local: {0}:{1}\nRemote: {2}:{3}\nState: {4}\n", 
        info.LocalEndPoint.Address, info.LocalEndPoint.Port,
        info.RemoteEndPoint.Address, info.RemoteEndPoint.Port,
        info.State.ToString());
}
Console.ReadLine();

Source: Netstat in C#

A bit more research bring this: Build your own netstat.exe with c#. This uses P/Invoke to call GetExtendedTcpTable and using same structure as netstat.

How do I get process name of an open port in C#?

http://www.codeproject.com/KB/IP/iphlpapi.aspx might also help

Determine if a server is listening on a given port

The process is actually very simple.

using (var socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
{
    try
    {
        socket.Connect(host, port);
    }
    catch (SocketException ex)
    {
        if (ex.SocketErrorCode == SocketError.ConnectionRefused) 
        {
            // ...
        }
    }
}

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