C#简单实现SNMP的方法

2019-10-29 21:41:07

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这篇文章主要介绍了C#简单实现SNMP的方法,通过一个简单的自定义类分析了C#实现SNMP的相关技巧,具有一定参考借鉴价值,需要的朋友可以参考下

本文实例讲述了C#简单实现SNMP的方法。分享给大家供大家参考。具体如下：

/**

C# Network Programming

by Richard Blum

Publisher: Sybex

ISBN: 0782141765

*/

using System;

using System.Text;

using System.Net;

using System.Net.Sockets;

public class SimpleSNMP

{

public static void Main(string[] argv)

{

int commlength, miblength, datatype, datalength, datastart;

int uptime = 0;

string output;

SNMP conn = new SNMP();

byte[] response = new byte[1024];

Console.WriteLine("Device SNMP information:");

// Send sysName SNMP request

response = conn.get("get", argv[0], argv[1], "1.3.6.1.2.1.1.5.0");

if (response[0] == 0xff)

{

Console.WriteLine("No response from {0}", argv[0]);

return;

}

// If response, get the community name and MIB lengths

commlength = Convert.ToInt16(response[6]);

miblength = Convert.ToInt16(response[23 + commlength]);

// Extract the MIB data from the SNMP response

datatype = Convert.ToInt16(response[24 + commlength + miblength]);

datalength = Convert.ToInt16(response[25 + commlength + miblength]);

datastart = 26 + commlength + miblength;

output = Encoding.ASCII.GetString(response, datastart, datalength);

Console.WriteLine(" sysName - Datatype: {0}, Value: {1}",

datatype, output);

// Send a sysLocation SNMP request

response = conn.get("get", argv[0], argv[1], "1.3.6.1.2.1.1.6.0");

if (response[0] == 0xff)

{

Console.WriteLine("No response from {0}", argv[0]);

return;

}

// If response, get the community name and MIB lengths

commlength = Convert.ToInt16(response[6]);

miblength = Convert.ToInt16(response[23 + commlength]);

// Extract the MIB data from the SNMP response

datatype = Convert.ToInt16(response[24 + commlength + miblength]);

datalength = Convert.ToInt16(response[25 + commlength + miblength]);

datastart = 26 + commlength + miblength;

output = Encoding.ASCII.GetString(response, datastart, datalength);

Console.WriteLine(" sysLocation - Datatype: {0}, Value: {1}", datatype, output);

// Send a sysContact SNMP request

response = conn.get("get", argv[0], argv[1], "1.3.6.1.2.1.1.4.0");

if (response[0] == 0xff)

{

Console.WriteLine("No response from {0}", argv[0]);

return;

}

// Get the community and MIB lengths

commlength = Convert.ToInt16(response[6]);

miblength = Convert.ToInt16(response[23 + commlength]);

// Extract the MIB data from the SNMP response

datatype = Convert.ToInt16(response[24 + commlength + miblength]);

datalength = Convert.ToInt16(response[25 + commlength + miblength]);

datastart = 26 + commlength + miblength;

output = Encoding.ASCII.GetString(response, datastart, datalength);

Console.WriteLine(" sysContact - Datatype: {0}, Value: {1}",

datatype, output);

// Send a SysUptime SNMP request

response = conn.get("get", argv[0], argv[1], "1.3.6.1.2.1.1.3.0");

if (response[0] == 0xff)

{

Console.WriteLine("No response from {0}", argv[0]);

return;

}

// Get the community and MIB lengths of the response

commlength = Convert.ToInt16(response[6]);

miblength = Convert.ToInt16(response[23 + commlength]);

// Extract the MIB data from the SNMp response

datatype = Convert.ToInt16(response[24 + commlength + miblength]);

datalength = Convert.ToInt16(response[25 + commlength + miblength]);

datastart = 26 + commlength + miblength;

// The sysUptime value may by a multi-byte integer

// Each byte read must be shifted to the higher byte order

while(datalength > 0)

{

uptime = (uptime << 8) + response[datastart++];

datalength--;

}

Console.WriteLine(" sysUptime - Datatype: {0}, Value: {1}",

datatype, uptime);

}

}

class SNMP

{

public SNMP()

{

}

public byte[] get(string request, string host, string community, string mibstring)

{

byte[] packet = new byte[1024];

byte[] mib = new byte[1024];

int snmplen;

int comlen = community.Length;

string[] mibvals = mibstring.Split('.');

int miblen = mibvals.Length;

int cnt = 0, temp, i;

int orgmiblen = miblen;

int pos = 0;

// Convert the string MIB into a byte array of integer values

// Unfortunately, values over 128 require multiple bytes

// which also increases the MIB length

for (i = 0; i < orgmiblen; i++)

{

temp = Convert.ToInt16(mibvals[i]);

if (temp > 127)

{

mib[cnt] = Convert.ToByte(128 + (temp / 128));

mib[cnt + 1] = Convert.ToByte(temp - ((temp / 128) * 128));

cnt += 2;

miblen++;

} else

{

mib[cnt] = Convert.ToByte(temp);

cnt++;

}

}

snmplen = 29 + comlen + miblen - 1; //Length of entire SNMP packet

//The SNMP sequence start

packet[pos++] = 0x30; //Sequence start

packet[pos++] = Convert.ToByte(snmplen - 2); //sequence size

//SNMP version

packet[pos++] = 0x02; //Integer type

packet[pos++] = 0x01; //length

packet[pos++] = 0x00; //SNMP version 1

//Community name

packet[pos++] = 0x04; // String type

packet[pos++] = Convert.ToByte(comlen); //length

//Convert community name to byte array

byte[] data = Encoding.ASCII.GetBytes(community);

for (i = 0; i < data.Length; i++)

{

packet[pos++] = data[i];

}

//Add GetRequest or GetNextRequest value

if (request == "get")

packet[pos++] = 0xA0;

else

packet[pos++] = 0xA1;

packet[pos++] = Convert.ToByte(20 + miblen - 1); //Size of total MIB

//Request ID

packet[pos++] = 0x02; //Integer type

packet[pos++] = 0x04; //length

packet[pos++] = 0x00; //SNMP request ID

packet[pos++] = 0x00;

packet[pos++] = 0x00;

packet[pos++] = 0x01;

//Error status

packet[pos++] = 0x02; //Integer type

packet[pos++] = 0x01; //length

packet[pos++] = 0x00; //SNMP error status

//Error index

packet[pos++] = 0x02; //Integer type

packet[pos++] = 0x01; //length

packet[pos++] = 0x00; //SNMP error index

//Start of variable bindings

packet[pos++] = 0x30; //Start of variable bindings sequence

packet[pos++] = Convert.ToByte(6 + miblen - 1); // Size of variable binding

packet[pos++] = 0x30; //Start of first variable bindings sequence

packet[pos++] = Convert.ToByte(6 + miblen - 1 - 2); // size

packet[pos++] = 0x06; //Object type

packet[pos++] = Convert.ToByte(miblen - 1); //length

//Start of MIB

packet[pos++] = 0x2b;

//Place MIB array in packet

for(i = 2; i < miblen; i++)

packet[pos++] = Convert.ToByte(mib[i]);

packet[pos++] = 0x05; //Null object value

packet[pos++] = 0x00; //Null

//Send packet to destination

Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram,

ProtocolType.Udp);

sock.SetSocketOption(SocketOptionLevel.Socket,

SocketOptionName.ReceiveTimeout, 5000);

IPHostEntry ihe = Dns.Resolve(host);

IPEndPoint iep = new IPEndPoint(ihe.AddressList[0], 161);

EndPoint ep = (EndPoint)iep;

sock.SendTo(packet, snmplen, SocketFlags.None, iep);

//Receive response from packet

try

{

int recv = sock.ReceiveFrom(packet, ref ep);

} catch (SocketException)

{

packet[0] = 0xff;

}

return packet;

}

public string getnextMIB(byte[] mibin)

{

string output = "1.3";

int commlength = mibin[6];

int mibstart = 6 + commlength + 17; //find the start of the mib section

//The MIB length is the length defined in the SNMP packet

// minus 1 to remove the ending .0, which is not used

int miblength = mibin[mibstart] - 1;

mibstart += 2; //skip over the length and 0x2b values

int mibvalue;

for(int i = mibstart; i < mibstart + miblength; i++)

{

mibvalue = Convert.ToInt16(mibin[i]);

if (mibvalue > 128)

{

mibvalue = (mibvalue/128)*128 + Convert.ToInt16(mibin[i+1]);

//ERROR here, it should be mibvalue = (mibvalue-128)*128 + Convert.ToInt16(mibin[i+1]);

//for mib values greater than 128, the math is not adding up correctly

i++;

}

output += "." + mibvalue;

}

return output;

}

}