一个SNMP类!
  1using System;
  2using System.Net;
  3using System.Net.Sockets;
  4using System.Text;
  5class SNMP
  6{
  7  public SNMP()
  8  {
  9  }
 10  public byte[] get(string request, string host, string community, string_  mibstring)
 11  {
 12   byte[] packet = new byte[1024];
 13   byte[] mib = new byte[1024];
 14   int snmplen;
 15   int comlen = community.Length;
 16   string[] mibvals = mibstring.Split('.');
 17   int miblen = mibvals.Length;
 18   int cnt = 0, temp, i;
 19   int orgmiblen = miblen;
 20   int pos = 0;
 21   // Convert the string MIB into a byte array of integer values
 22   // Unfortunately, values over 128 require multiple bytes
 23   // which also increases the MIB length
 24   for (i = 0; i < orgmiblen; i++)
 25   {
 26     temp = Convert.ToInt16(mibvals[i]);
 27     if (temp > 127)
 28     {
 29      mib[cnt] = Convert.ToByte(128 + (temp / 128));
 30      mib[cnt + 1] = Convert.ToByte(temp - ((temp / 128) * 128));
 31      cnt += 2;
 32      miblen++;
 33     } else
 34     {
 35      mib[cnt] = Convert.ToByte(temp);
 36      cnt++;
 37     }
 38   }
 39   snmplen = 29 + comlen + miblen - 1; //Length of entire SNMP packet
 40   //The SNMP sequence start
 41   packet[pos++] = 0x30; //Sequence start
 42   packet[pos++] = Convert.ToByte(snmplen - 2); //sequence size
 43   //SNMP version
 44   packet[pos++] = 0x02; //Integer type
 45   packet[pos++] = 0x01; //length
 46   packet[pos++] = 0x00; //SNMP version 1
 47   //Community name
 48   packet[pos++] = 0x04; // String type
 49   packet[pos++] = Convert.ToByte(comlen); //length
 50   //Convert community name to byte array
 51   byte[] data = Encoding.ASCII.GetBytes(community);
 52   for (i = 0; i < data.Length; i++)
 53   {
 54     packet[pos++] = data[i];
 55   }
 56   //Add GetRequest or GetNextRequest value
 57   if (request == "get")
 58     packet[pos++] = 0xA0;
 59   else
 60     packet[pos++] = 0xA1;
 61   packet[pos++] = Convert.ToByte(20 + miblen - 1); //Size of total MIB
 62   //Request ID
 63   packet[pos++] = 0x02; //Integer type
 64   packet[pos++] = 0x04; //length
 65   packet[pos++] = 0x00; //SNMP request ID
 66   packet[pos++] = 0x00;
 67   packet[pos++] = 0x00;
 68   packet[pos++] = 0x01;
 69   //Error status
 70   packet[pos++] = 0x02; //Integer type
 71   packet[pos++] = 0x01; //length
 72   packet[pos++] = 0x00; //SNMP error status
 73   //Error index
 74   packet[pos++] = 0x02; //Integer type
 75   packet[pos++] = 0x01; //length
 76   packet[pos++] = 0x00; //SNMP error index
 77   //Start of variable bindings
 78   packet[pos++] = 0x30; //Start of variable bindings sequence
 79   packet[pos++] = Convert.ToByte(6 + miblen - 1); // Size of variable binding
 80   packet[pos++] = 0x30; //Start of first variable bindings sequence
 81   packet[pos++] = Convert.ToByte(6 + miblen - 1 - 2); // size
 82   packet[pos++] = 0x06; //Object type
 83   packet[pos++] = Convert.ToByte(miblen - 1); //length
 84   //Start of MIB
 85   packet[pos++] = 0x2b;
 86   //Place MIB array in packet
 87   for(i = 2; i < miblen; i++)
 88     packet[pos++] = Convert.ToByte(mib[i]);
 89   packet[pos++] = 0x05; //Null object value
 90   packet[pos++] = 0x00; //Null
 91   //Send packet to destination
 92   Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram,
 93            ProtocolType.Udp);
 94   sock.SetSocketOption(SocketOptionLevel.Socket,
 95           SocketOptionName.ReceiveTimeout, 5000);
 96   IPHostEntry ihe = Dns.Resolve(host);
 97   IPEndPoint iep = new IPEndPoint(ihe.AddressList[0], 161);
 98   EndPoint ep = (EndPoint)iep;
 99   sock.SendTo(packet, snmplen, SocketFlags.None, iep);
100   //Receive response from packet
101   try
102   {
103     int recv = sock.ReceiveFrom(packet, ref ep);
104   } catch (SocketException)
105   {
106     packet[0] = 0xff;
107   }
108   return packet;
109  }
110}
111