why pysnmp "get next or nextcmd" showing only two interfaces?

In my virtual box there are four interfaces and loopback interface are present as below. 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

When i am trying to get the interfaces info using pysnmp nextcmd, it always shows only two interfaces eth0, lo.

Using this example:

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]))

Output:

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

How about the remaining interfaces? It is not been displayed? Any ideas?

To fetch the interfaces in your local machine(virtual box), Modify the logic as below.

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>