Enhanced SNMP WALK

By Lex Li

This page shows you information about how to utilize MIB documents to enhance SNMP WALK operations.

In this article:

Background

#SNMP Library has a sample project snmpd that can work as a test agent.

If we use snmpwalk sample to query all objects from this agent, the following information can be seen,

> ./snmpwalk.exe -c=public -v=1 -m=subtree localhost 1.3.6
Variable: Id: 1.3.6.1.2.1.1.1.0; Data: #SNMP Agent on .NET Standard
Variable: Id: 1.3.6.1.2.1.1.2.0; Data: 1.3.6.1
Variable: Id: 1.3.6.1.2.1.1.3.0; Data: 00:04:20.9500000
Variable: Id: 1.3.6.1.2.1.1.4.0; Data: UNKNOWN
Variable: Id: 1.3.6.1.2.1.1.5.0; Data: UNKNOWN
Variable: Id: 1.3.6.1.2.1.1.6.0; Data:
Variable: Id: 1.3.6.1.2.1.1.7.0; Data: 72
Variable: Id: 1.3.6.1.2.1.1.8.0; Data: 00:00:00
Variable: Id: 1.3.6.1.2.1.1.9.1.1.1; Data: 1
Variable: Id: 1.3.6.1.2.1.1.9.1.1.2; Data: 2
Variable: Id: 1.3.6.1.2.1.1.9.1.2.1; Data: 1.3
Variable: Id: 1.3.6.1.2.1.1.9.1.2.2; Data: 1.4
Variable: Id: 1.3.6.1.2.1.1.9.1.3.1; Data: Test1
Variable: Id: 1.3.6.1.2.1.1.9.1.3.2; Data: Test2
Variable: Id: 1.3.6.1.2.1.1.9.1.4.1; Data: 00:00:00.0100000
Variable: Id: 1.3.6.1.2.1.1.9.1.4.2; Data: 00:00:00.0200000
Variable: Id: 1.3.6.1.2.1.2.1.0; Data: 3
Variable: Id: 1.3.6.1.2.1.2.2.1.1.1; Data: 1
Variable: Id: 1.3.6.1.2.1.2.2.1.1.2; Data: 2
Variable: Id: 1.3.6.1.2.1.2.2.1.1.3; Data: 3
Variable: Id: 1.3.6.1.2.1.2.2.1.2.1; Data: Microsoft Hyper-V Network Adapter
Variable: Id: 1.3.6.1.2.1.2.2.1.2.2; Data: Microsoft Hyper-V Network Adapter #2
Variable: Id: 1.3.6.1.2.1.2.2.1.2.3; Data: Software Loopback Interface 1
Variable: Id: 1.3.6.1.2.1.2.2.1.3.1; Data: 6
Variable: Id: 1.3.6.1.2.1.2.2.1.3.2; Data: 6
Variable: Id: 1.3.6.1.2.1.2.2.1.3.3; Data: 24
Variable: Id: 1.3.6.1.2.1.2.2.1.4.1; Data: 1500
Variable: Id: 1.3.6.1.2.1.2.2.1.4.2; Data: 1500
Variable: Id: 1.3.6.1.2.1.2.2.1.4.3; Data: -1
Variable: Id: 1.3.6.1.2.1.2.2.1.5.1; Data: 1410065408
Variable: Id: 1.3.6.1.2.1.2.2.1.5.2; Data: 866700000
Variable: Id: 1.3.6.1.2.1.2.2.1.5.3; Data: 1073741824
Variable: Id: 1.3.6.1.2.1.2.2.1.6.1; Data:  §☺☺
Variable: Id: 1.3.6.1.2.1.2.2.1.6.2; Data:  §☻☺
Variable: Id: 1.3.6.1.2.1.2.2.1.6.3; Data:
Variable: Id: 1.3.6.1.2.1.2.2.1.7.1; Data: 1
Variable: Id: 1.3.6.1.2.1.2.2.1.7.2; Data: 1
Variable: Id: 1.3.6.1.2.1.2.2.1.7.3; Data: 1
Variable: Id: 1.3.6.1.2.1.2.2.1.8.1; Data: 1
Variable: Id: 1.3.6.1.2.1.2.2.1.8.2; Data: 1
Variable: Id: 1.3.6.1.2.1.2.2.1.8.3; Data: 1
Variable: Id: 1.3.6.1.2.1.2.2.1.9.1; Data: 00:00:00
Variable: Id: 1.3.6.1.2.1.2.2.1.9.2; Data: 00:00:00
Variable: Id: 1.3.6.1.2.1.2.2.1.9.3; Data: 00:00:00
Variable: Id: 1.3.6.1.2.1.2.2.1.10.1; Data: 7168160
Variable: Id: 1.3.6.1.2.1.2.2.1.10.2; Data: 49028
Variable: Id: 1.3.6.1.2.1.2.2.1.10.3; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.11.1; Data: 6362
Variable: Id: 1.3.6.1.2.1.2.2.1.11.2; Data: 208
Variable: Id: 1.3.6.1.2.1.2.2.1.11.3; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.12.1; Data: 92
Variable: Id: 1.3.6.1.2.1.2.2.1.12.2; Data: 104
Variable: Id: 1.3.6.1.2.1.2.2.1.12.3; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.13.1; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.13.2; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.13.3; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.14.1; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.14.2; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.14.3; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.15.1; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.15.2; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.15.3; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.16.1; Data: 1131548
Variable: Id: 1.3.6.1.2.1.2.2.1.16.2; Data: 32719
Variable: Id: 1.3.6.1.2.1.2.2.1.16.3; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.17.1; Data: 4480
Variable: Id: 1.3.6.1.2.1.2.2.1.17.2; Data: 203
Variable: Id: 1.3.6.1.2.1.2.2.1.17.3; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.18.1; Data: 213
Variable: Id: 1.3.6.1.2.1.2.2.1.18.2; Data: 156
Variable: Id: 1.3.6.1.2.1.2.2.1.18.3; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.19.1; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.19.2; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.19.3; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.20.1; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.20.2; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.20.3; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.21.1; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.21.2; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.21.3; Data: 0
Variable: Id: 1.3.6.1.2.1.2.2.1.22.1; Data: 0.0
Variable: Id: 1.3.6.1.2.1.2.2.1.22.2; Data: 0.0
Variable: Id: 1.3.6.1.2.1.2.2.1.22.3; Data: 0.0

The output has several issues that you can easily identify,

  • All OIDs are in numeric form.

  • Special encoded data such as MAC addresses (like 1.3.6.1.2.1.2.2.1.6.1), bits (such as 1.3.6.1.2.1.2.2.1.7.1) are displayed in raw format.

Utilizing MIB Documents

If we switch to an enhanced version of snmpwalk, then the output looks like this,

> ./snmpwalk.exe -c=public -v=1 -m=subtree localhost 1.3.6
Variable: Id: SNMPv2-MIB::sysDescr.0; Data: #SNMP Agent on .NET Standard
Variable: Id: SNMPv2-MIB::sysObjectID.0; Data: 1.3.6.1
Variable: Id: SNMPv2-MIB::sysUpTime.0; Data: 00:10:54
Variable: Id: SNMPv2-MIB::sysContact.0; Data: UNKNOWN
Variable: Id: SNMPv2-MIB::sysName.0; Data: UNKNOWN
Variable: Id: SNMPv2-MIB::sysLocation.0; Data:
Variable: Id: SNMPv2-MIB::sysServices.0; Data: 72
Variable: Id: SNMPv2-MIB::sysORLastChange.0; Data: 00:00:00
Variable: Id: SNMPv2-MIB::sysORIndex.1; Data: 1
Variable: Id: SNMPv2-MIB::sysORIndex.2; Data: 2
Variable: Id: SNMPv2-MIB::sysORID.1; Data: 1.3
Variable: Id: SNMPv2-MIB::sysORID.2; Data: 1.4
Variable: Id: SNMPv2-MIB::sysORDescr.1; Data: Test1
Variable: Id: SNMPv2-MIB::sysORDescr.2; Data: Test2
Variable: Id: SNMPv2-MIB::sysORUpTime.1; Data: 00:00:00.0100000
Variable: Id: SNMPv2-MIB::sysORUpTime.2; Data: 00:00:00.0200000
Variable: Id: IF-MIB::ifNumber.0; Data: 3
Variable: Id: IF-MIB::ifIndex.1; Data: 1
Variable: Id: IF-MIB::ifIndex.2; Data: 2
Variable: Id: IF-MIB::ifIndex.3; Data: 3
Variable: Id: IF-MIB::ifDescr.1; Data: Microsoft Hyper-V Network Adapter
Variable: Id: IF-MIB::ifDescr.2; Data: Microsoft Hyper-V Network Adapter #2
Variable: Id: IF-MIB::ifDescr.3; Data: Software Loopback Interface 1
Variable: Id: IF-MIB::ifType.1; Data: ethernetCsmacd(6)
Variable: Id: IF-MIB::ifType.2; Data: ethernetCsmacd(6)
Variable: Id: IF-MIB::ifType.3; Data: softwareLoopback(24)
Variable: Id: IF-MIB::ifMtu.1; Data: 1500
Variable: Id: IF-MIB::ifMtu.2; Data: 1500
Variable: Id: IF-MIB::ifMtu.3; Data: -1
Variable: Id: IF-MIB::ifSpeed.1; Data: 1410065408
Variable: Id: IF-MIB::ifSpeed.2; Data: 866700000
Variable: Id: IF-MIB::ifSpeed.3; Data: 1073741824
Variable: Id: IF-MIB::ifPhysAddress.1; Data: 00-15-5D-01-08-01
Variable: Id: IF-MIB::ifPhysAddress.2; Data: 00-15-5D-01-08-02
Variable: Id: IF-MIB::ifPhysAddress.3; Data:
Variable: Id: IF-MIB::ifAdminStatus.1; Data: up(1)
Variable: Id: IF-MIB::ifAdminStatus.2; Data: up(1)
Variable: Id: IF-MIB::ifAdminStatus.3; Data: up(1)
Variable: Id: IF-MIB::ifOperStatus.1; Data: up(1)
Variable: Id: IF-MIB::ifOperStatus.2; Data: up(1)
Variable: Id: IF-MIB::ifOperStatus.3; Data: up(1)
Variable: Id: IF-MIB::ifLastChange.1; Data: 00:00:00
Variable: Id: IF-MIB::ifLastChange.2; Data: 00:00:00
Variable: Id: IF-MIB::ifLastChange.3; Data: 00:00:00
Variable: Id: IF-MIB::ifInOctets.1; Data: 10431787
Variable: Id: IF-MIB::ifInOctets.2; Data: 60373
Variable: Id: IF-MIB::ifInOctets.3; Data: 0
Variable: Id: IF-MIB::ifInUcastPkts.1; Data: 8868
Variable: Id: IF-MIB::ifInUcastPkts.2; Data: 277
Variable: Id: IF-MIB::ifInUcastPkts.3; Data: 0
Variable: Id: IF-MIB::ifInNUcastPkts.1; Data: 93
Variable: Id: IF-MIB::ifInNUcastPkts.2; Data: 139
Variable: Id: IF-MIB::ifInNUcastPkts.3; Data: 0
Variable: Id: IF-MIB::ifInDiscards.1; Data: 0
Variable: Id: IF-MIB::ifInDiscards.2; Data: 0
Variable: Id: IF-MIB::ifInDiscards.3; Data: 0
Variable: Id: IF-MIB::ifInErrors.1; Data: 0
Variable: Id: IF-MIB::ifInErrors.2; Data: 0
Variable: Id: IF-MIB::ifInErrors.3; Data: 0
Variable: Id: IF-MIB::ifInUnknownProtos.1; Data: 0
Variable: Id: IF-MIB::ifInUnknownProtos.2; Data: 0
Variable: Id: IF-MIB::ifInUnknownProtos.3; Data: 0
Variable: Id: IF-MIB::ifOutOctets.1; Data: 1341284
Variable: Id: IF-MIB::ifOutOctets.2; Data: 37650
Variable: Id: IF-MIB::ifOutOctets.3; Data: 0
Variable: Id: IF-MIB::ifOutUcastPkts.1; Data: 6057
Variable: Id: IF-MIB::ifOutUcastPkts.2; Data: 272
Variable: Id: IF-MIB::ifOutUcastPkts.3; Data: 0
Variable: Id: IF-MIB::ifOutNUcastPkts.1; Data: 213
Variable: Id: IF-MIB::ifOutNUcastPkts.2; Data: 156
Variable: Id: IF-MIB::ifOutNUcastPkts.3; Data: 0
Variable: Id: IF-MIB::ifOutDiscards.1; Data: 0
Variable: Id: IF-MIB::ifOutDiscards.2; Data: 0
Variable: Id: IF-MIB::ifOutDiscards.3; Data: 0
Variable: Id: IF-MIB::ifOutErrors.1; Data: 0
Variable: Id: IF-MIB::ifOutErrors.2; Data: 0
Variable: Id: IF-MIB::ifOutErrors.3; Data: 0
Variable: Id: IF-MIB::ifOutQLen.1; Data: 0
Variable: Id: IF-MIB::ifOutQLen.2; Data: 0
Variable: Id: IF-MIB::ifOutQLen.3; Data: 0
Variable: Id: IF-MIB::ifSpecific.1; Data: 0.0
Variable: Id: IF-MIB::ifSpecific.2; Data: 0.0
Variable: Id: IF-MIB::ifSpecific.3; Data: 0.0

Not only all OIDs are displayed in textual form, but also we see MAC addresses and bits in correct format (like 00-15-5D-01-08-01 and up(1)).

You can find the sample code at GitHub.