C#

#if !NET11 && !NET20
#error "Missing version of .NET Framework (define one of NET11, NET20)"
#endif

using System;
using System.DirectoryServices;			// DirectoryEntry
using System.Management;
using System.Net;						// DNS
using System.Runtime.InteropServices;	// DllImport
using System.Threading;

using LP_Core;

namespace LP_Platform {
	/// <summary>
	/// LP_Workgroup scans the network for machines in a workgroup.
	/// It uses Active Directory on the host machine.
	/// </summary>
	public class LP_Workgroup {
		//====================================================================================
		// class constants
		//====================================================================================
		/// <summary>logging object</summary>
		protected static ILP_Environment env=LP_Environment.GetEnvironment();

		//====================================================================================
		// object variables
		//====================================================================================
		protected string name;

		public LP_Workgroup() : this(null) {}

		public LP_Workgroup(string name) {
			if (name==null) {
				name="<unknown>";
				IntPtr buf;
				int result=NetWkstaGetInfo(null, 100, out buf);
				env.log(0,"NetWkstaGetInfo result="+result);
				if (result==0) {
					WKSTA_INFO_100 info=(WKSTA_INFO_100)Marshal.PtrToStructure(buf, typeof(WKSTA_INFO_100));
					name=info.wki100_langroup;
					env.log(0,"LP_Workgroup: workgroup="+name);
				}
				if (buf!=IntPtr.Zero) NetApiBufferFree(buf);
				result=NetWkstaUserGetInfo(null, 1, out buf);
				env.log(0,"NetWkstaUserGetInfo result="+result);
				if (result==0) {
					WKSTA_USER_INFO_1 info=(WKSTA_USER_INFO_1)Marshal.PtrToStructure(buf, typeof(WKSTA_USER_INFO_1));
					string s1=info.wkui1_username;
					env.log(0,"LP_Workgroup: username="+s1);
					string s2=info.wkui1_logon_domain;
					env.log(0,"LP_Workgroup: logon domain="+s2);
					string s3=info.wkui1_oth_domains;
					env.log(0,"LP_Workgroup: other domains="+s3);
					string s4=info.wkui1_logon_server;
					env.log(0,"LP_Workgroup: logon server="+s4);
				}
				if (buf!=IntPtr.Zero) NetApiBufferFree(buf);
			}
			this.name=name;
		}

		public string Name {get {return name;}}

		public void Scan(LPW_ProgressMessage msg) {
			msg.Title="Searching machines in workgroup "+name;
			env.alert(msg);
			env.outputBegin();
			LP_CancellableThread thread=new LP_CancellableThread(msg);
			thread.Start(new LP_ObjectHandler(scanner), msg);
		}

		// Scan the active directory to find all computers in the workgroup,
		// and to identify their IP address(es) and MAC address(es).
		// inspired by http://www.codeproject.com/cs/internet/host_info_within_network.asp
		private void scanner(object arg) {
			LPW_ProgressMessage msg=arg as LPW_ProgressMessage;
			env.output("Searching machines in workgroup "+name);
			DirectoryEntry domainEntry=new DirectoryEntry("WinNT://"+name);
			domainEntry.Children.SchemaFilter.Add("computer");
			int NAMELEN=0;
			foreach(DirectoryEntry machine in domainEntry.Children) {
				int i=machine.Name.Length+1;
				if (i>NAMELEN) NAMELEN=i;
			}
			foreach(DirectoryEntry machine in domainEntry.Children) {
				msg.Progress(1);
				string machineName=machine.Name;
				string longname=machineName.PadRight(NAMELEN);
				env.log(0,"machineName="+machineName);
				IPHostEntry hostEntry=null;
				try {
#if NET11
					hostEntry=Dns.GetHostByName(machineName);
#elif NET20
					hostEntry=Dns.GetHostEntry(machineName);
#endif
				} catch(Exception exc) {
					env.output("    "+longname+" unable to connect ("+exc.Message+")");
				}
				if (hostEntry!=null) {
					IPAddress[] IPAS=hostEntry.AddressList;
					foreach(IPAddress IPA in IPAS) {
						msg.Progress(1);
						string IP=" IP="+IPA.ToString().PadRight(16);
						env.log(0, IP);
						byte[] ab=new byte[6];
						int len=ab.Length;
						// now get Physical Address; the simple way would be
						//int r=SendARP((int)IPA.Address, 0, ab, ref len);
						// but this is obsolete since .NET 2.0; hence:
						byte[] b=IPA.GetAddressBytes();
						int IPAadr=(((((b[0]<<8)|b[1])<<8)|b[2])<<8)|b[3];
						int r=SendARP(IPAadr, 0, ab, ref len);
						string MAC=" MAC="+BitConverter.ToString(ab, 0, 6);
						env.log(0, MAC);
						env.output("    "+longname+IP+MAC);
						longname=" ".PadRight(NAMELEN);
					}			
				}
			}
#if true
			env.output("All entries");
			domainEntry=new DirectoryEntry("WinNT://"+name);
			//domainEntry=new DirectoryEntry("WinNT://");
			//domainEntry.Children.SchemaFilter.Add("WLAN");
			DirectoryEntries children=domainEntry.Children;
			foreach(DirectoryEntry entry in domainEntry.Children) {
				try {
					env.output("    properties of "+entry.Name);
					// this code fails when NETDISK300 is switched on
					PropertyCollection props=entry.Properties;
					foreach(string s in props.PropertyNames) {
						object obj=props[s].Value;
						env.output("        "+s+"="+obj.ToString());
					}
				} catch(Exception exc) {
					env.output("        Exception: "+exc.Message);
				}
			}
#endif
			aha();
			env.outputEnd();
			//Thread.Sleep(5000);
			msg.Done(true);
		}

		public void aha() {
			env.output("PRINTERS");
			ManagementScope mgmtscope=new ManagementScope(@"\root\cimv2");
			mgmtscope.Connect();
			ManagementObjectSearcher objsearcher=new ManagementObjectSearcher(
				"Select * from Win32_Printer");
			foreach(ManagementObject printer in objsearcher.Get()) {
				//if(printer["WorkOffline"].ToString().Equals("true"))
				string printername=printer["Name"].ToString();
				env.output("    "+printername);
				foreach(PropertyData pd in printer.Properties) {
					env.output("        "+pd.Name+"="+pd.Value);
				}
			}
		}

		[DllImport("Netapi32.dll", ExactSpelling=true)]
		public static extern int NetWkstaGetInfo(
			string servername,			// LPWSTR
			int level,					// DWORD
			out IntPtr buf				// WKSTA_INFO_100 wksta	// LPBYTE*
			);

		[DllImport("Netapi32.dll", ExactSpelling=true)]
		public static extern int NetWkstaUserGetInfo(
			string reserved,			// LPWSTR
			int level,					// DWORD
			out IntPtr buf				// WKSTA_USER_INFO_1101 wksta	// LPBYTE*
			);

		[DllImport("Netapi32.dll", ExactSpelling=true)]
		public static extern int NetApiBufferFree(IntPtr buf);

		[DllImport("iphlpapi.dll", ExactSpelling=true)]
		public static extern int SendARP( int DestIP, int SrcIP, [Out] byte[] pMacAddr, ref int PhyAddrLen);

		[StructLayout(LayoutKind.Sequential)]
			public struct WKSTA_INFO_100 {
			public int wki100_platform_id;			// DWORD
			[MarshalAs(System.Runtime.InteropServices.UnmanagedType.LPWStr)]
			public string wki100_computername;		// LPWSTR
			[MarshalAs(System.Runtime.InteropServices.UnmanagedType.LPWStr)]
			public string wki100_langroup;			// LPWSTR
			public int wki100_ver_major;			// DWORD
			public int wki100_ver_minor;			// DWORD
		}

		[StructLayout(LayoutKind.Sequential)]
			public struct WKSTA_USER_INFO_1 {
			[MarshalAs(System.Runtime.InteropServices.UnmanagedType.LPWStr)]
			public string wkui1_username;
			[MarshalAs(System.Runtime.InteropServices.UnmanagedType.LPWStr)]
			public string wkui1_logon_domain;
			[MarshalAs(System.Runtime.InteropServices.UnmanagedType.LPWStr)]
			public string wkui1_logon_server;
			[MarshalAs(System.Runtime.InteropServices.UnmanagedType.LPWStr)]
			public string wkui1_oth_domains;
		}
	}
}

int count=SecurityGroups.Items.Count;
byte[] aGroup = new byte[(count+7)/8]; // exact number of bytes needed in hex string
for (int index = 0; index < count; index++) {
    if (SecurityGroups.Items[index].Selected)
        aGroup[index/8] |= 1<<(index%8); // OR one of the numbers 1,2,4,8,16,32,64,128
}

aGroup[index/8] |= (byte)(1<<(index%8)); // OR one of the numbers 1,2,4,8,16,...