pyagentx snmp，代码如何链接到 MIB？

Question

我正在通过 python 查看 pyagentx（扩展 snmp 代理）。 https://github.com/rayed/pyagentx

我不明白示例代码是如何链接到 MIB 的。这里的示例是 class NetSnmpTestMibTable 从 NET-SNMP-EXAMPLES-MIB.txt http://www.net-snmp.org/docs/mibs/NET-SNMP-EXAMPLES-MIB.txt

链接到 netSnmpIETFWGTable

#!/usr/bin/env python
# -*- coding: utf-8 -*-

'''
Rayed Alrashed 2015-06-14
AgentX sub agent that implement some parts of NET-SNMP-EXAMPLES-MIB:
<http://www.net-snmp.org/docs/mibs/NET-SNMP-EXAMPLES-MIB.txt>
snmpwalk -v 2c -c public localhost NET-SNMP-EXAMPLES-MIB::netSnmpExampleScalars
snmptable -v 2c -c public -Ci localhost NET-SNMP-EXAMPLES-MIB::netSnmpIETFWGTable 
Try snmpset:
snmpset -v 2c -c public localhost NET-SNMP-EXAMPLES-MIB::netSnmpExampleInteger.0 i 10
snmpset -v 2c -c public localhost NET-SNMP-EXAMPLES-MIB::netSnmpExampleInteger.0 i 200
snmpset -v 2c -c public localhost NET-SNMP-EXAMPLES-MIB::netSnmpExampleString.0 s "Test"
'''

import time
import random
import pyagentx

def str_to_oid(data):
    length = len(data)
    oid_int = [str(ord(i)) for i in data]
    return str(length) + '.' + '.'.join(oid_int)


class NetSnmpTestMibScalar(pyagentx.Updater):

    def update(self):
        self.set_INTEGER('1.0', 1000)
        self.set_OCTETSTRING('3.0', 'String for NET-SNMP-EXAMPLES-MIB')
        self.set_OBJECTIDENTIFIER('4.0', '1.2')
        self.set_IPADDRESS('5.0', '127.0.0.1')
        self.set_COUNTER32('6.0', 2000)
        self.set_GAUGE32('7.0', 2000)
        self.set_TIMETICKS('8.0', 1000000)
        self.set_OPAQUE('9.0', 'Test')
        self.set_COUNTER64('10.0', 2000)


class NetSnmpTestMibTable(pyagentx.Updater):

    def update(self):
        # implement netSnmpIETFWGTable from NET-SNMP-EXAMPLES-MIB.txt
        # Number of entries in table is random to show that MIB is reset
        # on every update
        for i in range(random.randint(3, 5)):
            idx = str_to_oid('group%s' % (i+1))
            self.set_OCTETSTRING('1.1.2.' + idx, 'member 1')
            self.set_OCTETSTRING('1.1.3.' + idx, 'member 2')


class NetSnmpIntegerSet(pyagentx.SetHandler):

    def test(self, oid, data):
        if int(data) > 100:
            raise pyagentx.SetHandlerError()

    def commit(self, oid, data):
        print "COMMIT CALLED: %s = %s" % (oid, data)


class MyAgent(pyagentx.Agent):

    def setup(self):
        self.register('1.3.6.1.4.1.8072.2.1', NetSnmpTestMibScalar)
        self.register('1.3.6.1.4.1.8072.2.2', NetSnmpTestMibTable)
        self.register_set('1.3.6.1.4.1.8072.2.1.1.0', NetSnmpIntegerSet)


def main():
    pyagentx.setup_logging()
    try:
        a = MyAgent()
        a.start()
    except Exception as e:
        print "Unhandled exception:", e
        a.stop()
    except KeyboardInterrupt:
        a.stop()

if __name__=="__main__":
    main()

如果我运行一个命令，我得到了预期的输出，但我不确定它是如何工作的，代码如何知道更新netSnmpIETFWGTable？如您所见，我可以从中读取此示例代码设置的值：

snmptable -v 2c -c public -Ci localhost NET-SNMP-EXAMPLES-MIB::netSnmpIETFWGTable 
SNMP table: NET-SNMP-EXAMPLES-MIB::netSnmpIETFWGTable

   index nsIETFWGChair1 nsIETFWGChair2
"group1"     "member 1"     "member 2"
"group2"     "member 1"     "member 2"
"group3"     "member 1"     "member 2"

Answer 1

后台 MIB are like a DNS entry, they're just pointing to an ugly number 中的对象名称。

正在查找 NET-SNMP-EXAMPLES-MIB you can see netSnmpIETFWGTable defined as netSnmpExamples 2. Scrolling up a couple of lines shows netSnmpExamples defined as netSnmp 2. This is declared in the IMPORTS section as coming from NET-SNMP-MIB, so you'd need to look there to see what netSnmp is, etc. The SNMPv2-SMI MIB 是 SNMP 链的顶端。

你最终得到的是 netSnmpIETFWGTable 转换为 1.3.6.1.4.1.8072.2.2.1。查看文件底部的初始化代码，您可以看到此 OID 的父级链接到 class:

self.register('1.3.6.1.4.1.8072.2.2', NetSnmpTestMibTable)

希望能回答您的问题，"how does the code know to update netSnmpIETFWGTable."

您还可以试用 snmptranslate 实用程序，它比查看 MIB 文件更容易！

$ snmptranslate -On NET-SNMP-EXAMPLES-MIB::netSnmpIETFWGTable
.1.3.6.1.4.1.8072.2.2.1
$ snmptranslate -Of NET-SNMP-EXAMPLES-MIB::netSnmpIETFWGTable
.iso.org.dod.internet.private.enterprises.netSnmp.netSnmpExamples.netSnmpExampleTables.netSnmpIETFWGTable
$ snmptranslate 1.3.6.1.4.1.8072.2.2.1
NET-SNMP-EXAMPLES-MIB::netSnmpIETFWGTable
$ snmptranslate -Of 1.3.6.1.4.1.8072.2.2.1
.iso.org.dod.internet.private.enterprises.netSnmp.netSnmpExamples.netSnmpExampleTables.netSnmpIETFWGTable

pyagentx snmp，代码如何链接到 MIB？

pyagentx snmp, how is the code linked to the MIB?

python

snmp