snmp陷阱特定的陷阱代码

Question

我正在构建SNMP代理，现在正在处理陷阱消息。在开始编写陷阱消息的代码之前，我有一个问题：
在SNMPv1中，具体的陷阱代码是什么？我到处搜索的内容都只是表面上的定义，而我想获得一个深层的定义，其中包含它的可能。

Answer 1

An SNMPv1 trap PDU contains the following items:

1. Object Type generating the trap (this is an OID of type NOTIFICATION-TYPE)
2. Address of generating object (an IP address)
3. Generic Trap Data - one of the enumerations listed (0==coldStart, 1==warmStart ... 6==Enterprise)
4. Enterprise Trap Data - 0 or the specified enterprise trap data
5. Timestamp - timestamp trap was generated
6. Variable Bindings.

The generic trap data items 0-5 are defined explicitly in the spec as to what they mean, once you hit 6 (enterprise), then it is completely up to the definition supplied in the enterprise MIB. Unless you're actually loading and interpreting the content of the MIB that defines what the value means you can't actually understand what it means. If we look at the UCD-SNMP-MIB, it defines two trap types:

ucdTraps OBJECT IDENTIFIER ::= { ucdavis 251 }

ucdStart NOTIFICATION-TYPE
    STATUS  current
    DESCRIPTION
    "This trap could in principle be sent when the agent start"
    ::= { ucdTraps 1 }

ucdShutdown NOTIFICATION-TYPE
    STATUS current
    DESCRIPTION
    "This trap is sent when the agent terminates"
    ::= { ucdTraps 2 }

These correspond to OIDs .1.3.6.1.4.1.2021.251.1 and .1.3.6.1.4.1.2021.251.2 respectively.

The OID is interpreted as .1.3.6.1.4.1 == enterprises base, 2021 == UC Davis, 251 == ucdTraps and the trailing 1 or 2 is for usdStartup and usdShutdown respectively.

These traps would set the trap data type to 6 and, as they don't specify any content of the enterprise data field, it would not be interpretable.

Finally for variable data, it's a sequence of OID, value pairs, and needs to be unwrapped as specified ASN.1 data.

The coldStart OID is .1.3.6.1.6.3.1.1.5.1 - the base definitions are in the SNMPv2 MIB file for coldStart, warmStart and authenticationFailure, the definitions of linkDown and linkUp can be found in RFC2863.

to be honest, I wouldn't bother trying to interpret the data unless I was armed with the spec for the trap as without it you would have no way of understanding what it means.