using System.Text.RegularExpressions; using System.Diagnostics; public class test {         public test         {}         public static string GetCustomerMac(string IP) //para IP is the clients IP         {                string dirResults="";                ProcessStartInfo psi  = new ProcessStartInfo();                Process proc = new Process();                psi.FileName = "nbtstat";                psi.RedirectStandardInput = false;                psi.RedirectStandardOutput = true;                psi.Arguments = "-A " + IP;                psi.UseShellExecute = false;                proc = Process.Start(psi);                dirResults = proc.StandardOutput.ReadToEnd();                proc.WaitForExit();                dirResults=dirResults.Replace(" ","").Replace(" ","").Replace(" ","");               Regex reg=new Regex("Mac[ ]{0,}Address[ ]{0,}=[ ]{0,}(?<key>((.)*?)) __MAC",RegexOptions.IgnoreCase|RegexOptions.Compiled);                Match mc=reg.Match(dirResults+"__MAC");            if(mc.Success)             {                 return mc.Groups["key"].Value;            }             else            {                 reg=new Regex("Host not found",RegexOptions.IgnoreCase|RegexOptions.Compiled);                 mc=reg.Match(dirResults);             if(mc.Success)             {                  return "Host not found!";             }             else             {                  return "";             }        }   } }