c# - Enumerating Network Sessions

Question

I wanted to pull data about the connected network users from the Computer Management -> Shared Folders -> Sessions tab into my c# application. Can anybody guide me on what namespaces have to be used along with some sample code to import username and ip address from Computer Management -> Shared Folders -> Sessions tab?

Regards

Answer 1

You want NetSessionEnum, which:

Provides information about sessions established on a server.

When passed a level of 502, it'll return an array of:

...the name of the computer; name of the user; open files, pipes, and devices on the computer; and the name of the transport the client is using.

Luckily for you, pinvoke.net has the necessary signatures and even some sample code. Here's a full featured sample:

public class Program {
    public void Main(string[] args) {
        IntPtr pSessionInfo;
        IntPtr pResumeHandle = IntPtr.Zero;
        UInt32 entriesRead, totalEntries;

        var netStatus = NativeMethods.NetSessionEnum(
            null, // local computer
            null, // client name
            null, // username
            502, // include all info
            out pSessionInfo, // pointer to SESSION_INFO_502[]
            NativeMethods.MAX_PREFERRED_LENGTH,
            out entriesRead,
            out totalEntries,
            ref pResumeHandle
        );

        try {
            if (netStatus != NativeMethods.NET_API_STATUS.NERR_Success) {
                throw new InvalidOperationException(netStatus.ToString());
            }
            Console.WriteLine("Read {0} of {1} entries", entriesRead, totalEntries);
            for (int i = 0; i < entriesRead; i++) {
                var pCurrentSessionInfo = new IntPtr(pSessionInfo.ToInt32() + (NativeMethods.SESSION_INFO_502.SIZE_OF * i));
                var s = (NativeMethods.SESSION_INFO_502)Marshal.PtrToStructure(pCurrentSessionInfo, typeof(NativeMethods.SESSION_INFO_502));
                Console.WriteLine(
                    "User: {0}, Computer: {1}, Type: {2}, # Open Files: {3}, Connected Time: {4}s, Idle Time: {5}s, Guest: {6}",
                    s.sesi502_username,
                    s.sesi502_cname,
                    s.sesi502_cltype_name,
                    s.sesi502_num_opens,
                    s.sesi502_time,
                    s.sesi502_idle_time,
                    s.sesi502_user_flags == NativeMethods.SESSION_INFO_502_USER_FLAGS.SESS_GUEST
                );
            }
        } finally {
            NativeMethods.NetApiBufferFree(pSessionInfo);
        }
    }
}

public sealed class NativeMethods {
    [DllImport("netapi32.dll", SetLastError=true)]
    public static extern NET_API_STATUS NetSessionEnum(
            string serverName,
            string uncClientName,
            string userName,
            UInt32 level,
            out IntPtr bufPtr,
            int prefMaxLen,
            out UInt32 entriesRead,
            out UInt32 totalEntries,
            ref IntPtr resume_handle
    );

    [DllImport("netapi32.dll")]
    public static extern uint NetApiBufferFree(IntPtr Buffer);

    public const int MAX_PREFERRED_LENGTH = -1;

    public enum NET_API_STATUS : uint {
        NERR_Success = 0,
        NERR_InvalidComputer = 2351,
        NERR_NotPrimary = 2226,
        NERR_SpeGroupOp = 2234,
        NERR_LastAdmin = 2452,
        NERR_BadPassword = 2203,
        NERR_PasswordTooShort = 2245,
        NERR_UserNotFound = 2221,
        ERROR_ACCESS_DENIED = 5,
        ERROR_NOT_ENOUGH_MEMORY = 8,
        ERROR_INVALID_PARAMETER = 87,
        ERROR_INVALID_NAME = 123,
        ERROR_INVALID_LEVEL = 124,
        ERROR_MORE_DATA = 234 ,
        ERROR_SESSION_CREDENTIAL_CONFLICT = 1219
    }

    [StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
    public struct SESSION_INFO_502 {
        public static readonly int SIZE_OF = Marshal.SizeOf(typeof(SESSION_INFO_502));
        public string sesi502_cname;
        public string sesi502_username;
        public uint sesi502_num_opens;
        public uint sesi502_time;
        public uint sesi502_idle_time;
        public SESSION_INFO_502_USER_FLAGS sesi502_user_flags;
        public string sesi502_cltype_name;
        public string sesi502_transport;
    }

    public enum SESSION_INFO_502_USER_FLAGS : uint {
        SESS_GUEST = 1,
        SESS_NOENCRYPTION = 2
    }
}