如何使用python从SNMP获取数据？

Question

如何从fdb表获取值mac和vlan使用python？
在bash snmpwalk工作正常:

snmpwalk -v2c -c pub 192.168.0.100 1.3.6.1.2.1.17.7.1.2.2.1.2

pysnmp:

import os, sys
import socket
import random
from struct import pack, unpack
from datetime import datetime as dt

from pysnmp.entity.rfc3413.oneliner import cmdgen
from pysnmp.proto.rfc1902 import Integer, IpAddress, OctetString

ip='192.168.0.100'
community='pub'
value=(1,3,6,1,2,1,17,7,1,2,2,1,2)

generator = cmdgen.CommandGenerator()
comm_data = cmdgen.CommunityData('server', community, 1) # 1 means version SNMP v2c
transport = cmdgen.UdpTransportTarget((ip, 161))

real_fun = getattr(generator, 'getCmd')
res = (errorIndication, errorStatus, errorIndex, varBinds)\
    = real_fun(comm_data, transport, value)

if not errorIndication is None  or errorStatus is True:
       print "Error: %s %s %s %s" % res
else:
       print "%s" % varBinds

输出:[(ObjectName(1.3.6.1.2.1.17.7.1.2.2.1.2),NoSuchInstance(''))]

import netsnmp

def getmac():
    oid = netsnmp.VarList(netsnmp.Varbind('.1.3.6.1.2.1.17.7.1.2.2.1.2'))
    res = netsnmp.snmpgetbulk(oid, Version = 2, DestHost='192.168.0.100',
                           Community='pub')
    return res

print getmac()

输出:('27','27','25','27','27','27','24','27','25','18','4','27' ,'25','27','27','25','27','27','27','27','27','27','27','27',' 27','27','27','27','27','27','27','27','23','25','27','27','27' ,'25','27','25','27','27','25','27','27','27','27','27','27',' 27','27','27','25','27','27','27','27','27','27','27','27','27' ,'27','27','27','25','25','25','7','27','27','9','25','27',' 20','19','27','27','27','27','27','27','27','27','27','27','27' ,'27','27','27','11','25','27','27','27','27','27','27','27',' 27','27','27','27','27','27','27','25','27','27','27','27','27' ,'27','27','27','27','2','27','5','27','0','27','27','27',' 27','27')

第一个脚本(pysnmp)返回NoSuchInstance.第二个脚本(netsnmp)返回端口列表但没有mac和vlan.怎么了？

Answer 1

在pysnmp示例中,您正在执行SNMPGET(snmpget),而不是GETNEXT(snmpwalk).如果你改变了,

real_fun = getattr(generator, 'getCmd')

至

real_fun = getattr(generator, 'nextCmd')

你会开始看到有用的结果.

至于你在结果snmpwalk和python net-snmp绑定结果中看到的差异:snmpwalk并且snmpbulkget表现不同.如果你snmpbulkget从命令行执行一个与snmpwalk你的python net-snmp示例相同的选项的选项.

如果你在python net-snmp示例中更新以下行,

res = netsnmp.snmpgetbulk(oid, Version=2, DestHost='192.168.0.100', 
                          Community='pub')

至

res = netsnmp.snmpwalk(oid, Version=2, DestHost='192.168.0.100', 
                       Community='pub')

那么你应该从net-snmp你snmpwalk在命令行上看到的python 示例中获得相同的结果列表.