c# network discovery

Question

I'm developing a C# application and I need to discover computers and printers in the LAN. How can I do this from .NET? Is there any class in .NET framework I can use. Thanks for answers.

score 3 · Accepted Answer · answered Mar 28 '13 at 17:02

You can use DirectoryServices to get computers.

    System.DirectoryServices.DirectoryEntry winNtDirectoryEntries = new System.DirectoryServices.DirectoryEntry("WinNT:");
    List<String> computerNames = (from DirectoryEntry availDomains in winNtDirectoryEntries.Children 
                                  from DirectoryEntry pcNameEntry in availDomains.Children 
                                  where pcNameEntry.SchemaClassName.ToLower().Contains("computer") 
                                  select pcNameEntry.Name).ToList();

score 0 · Answer 2 · answered Mar 28 '13 at 16:56

This might help you: http://www.codeproject.com/Articles/16113/Retreiving-a-list-of-network-computer-names-using

using System;
using System.Runtime.InteropServices;
using System.Security;
using System.Collections;

namespace ListNetworkComputers
{
    #region NetworkBrowser CLASS
    /// <summary>
    /// Provides a mechanism for supplying
    // a list of all PC names in the local network.
    /// This collection of PC names is used in the form 
    /// 


    /// This class makes use of a DllImport instruction.
    /// The purpose of which is as follows:
    /// When a DllImport declaration is made
    /// in managed code (C#) it is a call to a legacy
    /// unmanaged code module, normally
    /// a C++ Dynamic Link Library. These C++ Dll's are
    /// usually part of the operating system API,
    /// or some other vendors API, and must be 
    /// used to carry out operations that are not
    /// native within the managed code C# framework. 
    /// This is fairly normal within the windows world.
    /// The only thing that needs careful consideration
    /// is the construction of the correct type of STRUCTS,
    /// object pointers, and attribute markers,
    /// which all contribute to making the link
    /// between managed (C#) and unmanaged code (C++)
    /// more seamless
    /// 

    /// This class makes use of the following Dll calls
    /// <list type="bullet">
    /// <item>
    /// <description> Netapi32.dll : NetServerEnum,
    /// The NetServerEnum function lists all servers
    /// of the specified type that are visible in
    /// a domain. For example, an application can call 
    /// NetServerEnum to list all domain controllers
    /// only or all SQL servers only.
    /// You can combine bit masks to list several
    /// types. For example, a value of 0x00000003 
    /// combines the bit masks for SV_TYPE_WORKSTATION
    /// (0x00000001) and SV_TYPE_SERVER (0x00000002).
    /// </description>
    /// </item>
    /// <item>
    /// <description> Netapi32.dll : NetApiBufferFree,
    /// The NetApiBufferFree function frees 
    /// the memory that the NetApiBufferAllocate
    /// function allocates. Call NetApiBufferFree 
    /// to free the memory that other network
    /// management functions return.</description>
    /// </item>
    /// </list>
    /// </summary>
    public sealed class NetworkBrowser
    {
        #region Dll Imports

        //declare the Netapi32 : NetServerEnum method import
        [DllImport("Netapi32", CharSet = CharSet.Auto,
        SetLastError = true),
        SuppressUnmanagedCodeSecurityAttribute]

        /// <summary>
        /// Netapi32.dll : The NetServerEnum function lists all servers
        /// of the specified type that are
        /// visible in a domain. For example, an 
        /// application can call NetServerEnum
        /// to list all domain controllers only
        /// or all SQL servers only.
        /// You can combine bit masks to list
        /// several types. For example, a value 
        /// of 0x00000003  combines the bit
        /// masks for SV_TYPE_WORKSTATION 
        /// (0x00000001) and SV_TYPE_SERVER (0x00000002)
        /// </summary>
        public static extern int NetServerEnum(
            string ServerNane, // must be null
            int dwLevel,
            ref IntPtr pBuf,
            int dwPrefMaxLen,
            out int dwEntriesRead,
            out int dwTotalEntries,
            int dwServerType,
            string domain, // null for login domain
            out int dwResumeHandle
            );

        //declare the Netapi32 : NetApiBufferFree method import
        [DllImport("Netapi32", SetLastError = true),
        SuppressUnmanagedCodeSecurityAttribute]

        /// <summary>
        /// Netapi32.dll : The NetApiBufferFree function frees 
        /// the memory that the NetApiBufferAllocate function allocates. 
        /// Call NetApiBufferFree to free
        /// the memory that other network 
        /// management functions return.
        /// </summary>
        public static extern int NetApiBufferFree(
            IntPtr pBuf);

        //create a _SERVER_INFO_100 STRUCTURE
        [StructLayout(LayoutKind.Sequential)]
        public struct _SERVER_INFO_100
        {
            internal int sv100_platform_id;
            [MarshalAs(UnmanagedType.LPWStr)]
            internal string sv100_name;
        }
        #endregion
        #region Public Constructor
        /// <SUMMARY>
        /// Constructor, simply creates a new NetworkBrowser object
        /// </SUMMARY>
        public NetworkBrowser()
        {

        }
        #endregion
        #region Public Methods
        /// <summary>
        /// Uses the DllImport : NetServerEnum
        /// with all its required parameters
        /// (see http://msdn.microsoft.com/library/default.asp?
        ///      url=/library/en-us/netmgmt/netmgmt/netserverenum.asp
        /// for full details or method signature) to
        /// retrieve a list of domain SV_TYPE_WORKSTATION
        /// and SV_TYPE_SERVER PC's
        /// </summary>
        /// <returns>Arraylist that represents
        /// all the SV_TYPE_WORKSTATION and SV_TYPE_SERVER
        /// PC's in the Domain</returns>
        public ArrayList getNetworkComputers()
        {
            //local fields
            ArrayList networkComputers = new ArrayList();
            const int MAX_PREFERRED_LENGTH = -1;
            int SV_TYPE_WORKSTATION = 1;
            int SV_TYPE_SERVER = 2;
            IntPtr buffer = IntPtr.Zero;
            IntPtr tmpBuffer = IntPtr.Zero;
            int entriesRead = 0;
            int totalEntries = 0;
            int resHandle = 0;
            int sizeofINFO = Marshal.SizeOf(typeof(_SERVER_INFO_100));


            try
            {
                //call the DllImport : NetServerEnum 
                //with all its required parameters
                //see http://msdn.microsoft.com/library/
                //default.asp?url=/library/en-us/netmgmt/netmgmt/netserverenum.asp
                //for full details of method signature
                int ret = NetServerEnum(null, 100, ref buffer,
                    MAX_PREFERRED_LENGTH,
                    out entriesRead,
                    out totalEntries, SV_TYPE_WORKSTATION |
                    SV_TYPE_SERVER, null, out 
                    resHandle);
                //if the returned with a NERR_Success 
                //(C++ term), =0 for C#
                if (ret == 0)
                {
                    //loop through all SV_TYPE_WORKSTATION 
                    //and SV_TYPE_SERVER PC's
                    for (int i = 0; i < totalEntries; i++)
                    {
                        //get pointer to, Pointer to the 
                        //buffer that received the data from
                        //the call to NetServerEnum. 
                        //Must ensure to use correct size of 
                        //STRUCTURE to ensure correct 
                        //location in memory is pointed to
                        tmpBuffer = new IntPtr((int)buffer +
                                   (i * sizeofINFO));
                        //Have now got a pointer to the list 
                        //of SV_TYPE_WORKSTATION and 
                        //SV_TYPE_SERVER PC's, which is unmanaged memory
                        //Needs to Marshal data from an 
                        //unmanaged block of memory to a 
                        //managed object, again using 
                        //STRUCTURE to ensure the correct data
                        //is marshalled 
                        _SERVER_INFO_100 svrInfo = (_SERVER_INFO_100)
                            Marshal.PtrToStructure(tmpBuffer,
                                    typeof(_SERVER_INFO_100));

                        //add the PC names to the ArrayList
                        networkComputers.Add(svrInfo.sv100_name);
                    }
                }
            }
            catch (Exception ex)
            {
                return null;
            }
            finally
            {
                //The NetApiBufferFree function frees 
                //the memory that the 
                //NetApiBufferAllocate function allocates
                NetApiBufferFree(buffer);
            }
            //return entries found
            return networkComputers;

        }
        #endregion
    }
    #endregion
}

Usage:

static void Main(string[] args)
{
    ListNetworkComputers.NetworkBrowser browser = new ListNetworkComputers.NetworkBrowser();
    ArrayList networks = browser.getNetworkComputers();
    foreach(object item in networks)
    {
        Console.WriteLine(item.ToString());
    }
    Console.Read();
}

This could help, but I was expecting a cleaner solution, something inside .NET. There really isn't a solution for this inside .NET framework? — user2220535, Mar 28 '13 at 17:52

score 0 · Answer 3 · answered Mar 28 '13 at 17:02

I'm not sure what you have tried; nor what your goal is. You can accomplish it within the following:

Launch a Process that will invoke a batch file, or powershell script.
Implement DirectoryServices.dll.

If you implemented the above, against a Workgroup

using (DirectoryEntry workgroup = new DirectoryEntry("WinNT://Workgroup"))
{
    foreach (DirectoryEntry childEntry in workgroup.Children)
    {
         Console.WriteLine(child.Name);
    }
}

That will allow you to test against a particular Workgroup. An example where it test against an entire Domain could be as follows:

using (DirectoryEntry domain = new DirectoryENtry("LDAP://" + domainName))
{
     domain.Children.SchemaFilter.Add("computer");
     foreach (DirectoryEntry d in domain.Childern)
     {
          Console.WriteLine(d.Name);
     }
}

As you can see you have quite a bit of flexibility here. Obviously you can implement a Process for a batch file that does Netview. That is very basic.

The other choice is Powershell. It has access to WMI so you'll be able to pull a lot of information. Plus with the large amount of IT Community Relying on it there are a lot of scripts available to accomplish this task.

Hopefully that helps.

c# network discovery

3 Answers3