CODEWITHSUNDEEP
c#udpsnmppacketpdu
user1333218
user1333218

Reputation: 9

Variable binding in SNMP PDU

I am developing a SNMP utility in C# which can fetch data from a specified device OID using the SNMP version 1 packet format.

I have almost completed it but their is a problem that I am not able to resolve.

I am successfully querying one variable by sending a single "Get" packet but I need to query multiple variables by sending a single packet.

I tried it in this way:

//variable bindings
p[bytepos++] = 0x30; //variable bindings sequence
p[bytepos++] = Convert.ToByte(6 + oid_len - 1 + 6 + oid_len2 - 1); // Size of variable binding
p[bytepos++] = 0x30; //first variable bindings sequence
p[bytepos++] = Convert.ToByte(4 + oid_len - 1); // size
p[bytepos++] = 0x06; //Object type
p[bytepos++] = Convert.ToByte(oid_len - 1 ); //length

//Start of MIB
p[bytepos++] = 0x2b;

for (i = 2; i < oid_len; i++)
    p[bytepos++] = Convert.ToByte(oid[i]);

p[bytepos++] = 0x05; //Null object value
p[bytepos++] = 0x00; //Null

//start of second variable bindings sequence
p[bytepos++] = 0x30; //Second variable bindings sequence
p[bytepos++] = Convert.ToByte(4 + oid_len2 - 1); // size
p[bytepos++] = 0x06; //Object type
p[bytepos++] = Convert.ToByte(oid_len2 - 1); //length

//Start of MIB
p[bytepos++] = 0x2b;

//Place MIB array in packet
for (i2 = 2; i2 < oid_len2; i2++)
    p[bytepos++] = Convert.ToByte(oid2[i2]);

p[bytepos++] = 0x05; //Null object value
p[bytepos++] = 0x00; //Null

I googled a lot but could not find any thing relevant.

Upvotes: 0

Views: 1787

Answers (1)

Lex Li
Lex Li

Reputation: 63264

Parsing SNMP PDU from raw bytes, is never as simple as the code segment you pasted.

To seriously use SNMP in C#, you need to consider one of the following libraries,

https://docs.lextudio.com/blog/product-review-snmp-libraries-for-net-evaluation-report-e13f25991cad

Upvotes: 3

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