为什么 pysnmp“get next 或 nextcmd”只显示两个接口？

Question

在我的虚拟盒子中有四个接口，环回接口如下。 eth0、eth1、eth2、eth3、lo。

VirtualBox:~/pysnmp# ip link
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 08:00:27:e1:eb:b9 brd ff:ff:ff:ff:ff:ff
3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 08:00:27:10:b8:4b brd ff:ff:ff:ff:ff:ff
4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 08:00:27:94:00:83 brd ff:ff:ff:ff:ff:ff
5: eth3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 08:00:27:62:2b:9f brd ff:ff:ff:ff:ff:ff

当我尝试使用 pysnmp nextcmd 获取接口信息时，它总是仅显示两个接口 eth0，lo。

使用这个例子：

from pysnmp.hlapi import *

for (errorIndication,
     errorStatus,
     errorIndex,
     varBinds) in nextCmd(SnmpEngine(),
                          CommunityData('public', mpModel=0),
                          UdpTransportTarget(('demo.xxxx.com', 161)),
                          ContextData(),
                          ObjectType(ObjectIdentity('IF-MIB', 'ifDescr')),
                          ObjectType(ObjectIdentity('IF-MIB', 'ifType')),
                          ObjectType(ObjectIdentity('IF-MIB', 'ifMtu')),
                          ObjectType(ObjectIdentity('IF-MIB', 'ifSpeed')),
                          ObjectType(ObjectIdentity('IF-MIB', 'ifPhysAddress')),
                          ObjectType(ObjectIdentity('IF-MIB', 'ifType')),
                          lexicographicMode=False):

    if errorIndication:
        print(errorIndication)
        break
    elif errorStatus:
        print('%s at %s' % (errorStatus.prettyPrint(),
                            errorIndex and varBinds[int(errorIndex)-1][0] or '?'))
        break
    else:
        for varBind in varBinds:
            print(' = '.join([x.prettyPrint() for x in varBind]))

输出：

root@VirtualBox:~/pysnmp# python tutorial.py 
IF-MIB::ifDescr.1 = lo
IF-MIB::ifType.1 = softwareLoopback
IF-MIB::ifMtu.1 = 16436
IF-MIB::ifSpeed.1 = 10000000
IF-MIB::ifPhysAddress.1 = 
IF-MIB::ifType.1 = softwareLoopback
IF-MIB::ifDescr.2 = eth0
IF-MIB::ifType.2 = ethernetCsmacd
IF-MIB::ifMtu.2 = 1500
IF-MIB::ifSpeed.2 = 100000000
IF-MIB::ifPhysAddress.2 = 00:12:79:62:f9:40
IF-MIB::ifType.2 = ethernetCsmacd

剩下的接口怎么样？是不是没有显示出来？有什么想法吗？

Answer 1

要获取本地机器（虚拟盒子）中的接口，请修改如下逻辑。

CommunityData('public', mpModel=0),   < "Community string is what you configured in your local machine refer snmd.conf file">



UdpTransportTarget(('localhost', 161)).    <Target IP address is our local host>

Answer 2

UdpTransportTarget(('demo.xxxx.com', 161))

。目标IP地址是demo.xxxx.com。它正在从此 IP 地址获取接口名称。