SNMP Oddity

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CentOS 2 Comments

Hi all,

Not sure if this is on topic or not.

I’m trying to query an SNMP value from CentOS 6 and I get a bad response if I don’t specify the MIB to use:

0 digimer@pulsar:~/anvil/striker$ snmpget -v2c -c public -m
/home/digimer/Downloads/APC/AP7900/MIB/powernet421.mib 10.255.2.1
.1.3.6.1.2.1.2.2.1.6.2
RFC1213-MIB::ifPhysAddress.2 = Hex-STRING: 00 C0 B7 5F 8A 85

0 digimer@pulsar:~/anvil/striker$ snmpget -v2c -c public 10.255.2.1
.1.3.6.1.2.1.2.2.1.6.2
IF-MIB::ifPhysAddress.2 = STRING: 0:c0:b7:5f:8a:85

Note the second reply is not returning the first character (should be
’00:’, returning ‘0:’.

Trying to request Hex doesn’t seem to help, either:

0 digimer@pulsar:~/anvil/striker$ snmpget -v2c -c public -Ox
10.255.2.1 .1.3.6.1.2.1.2.2.1.6.2
IF-MIB::ifPhysAddress.2 = STRING: 0:c0:b7:5f:8a:85

Any SNMP folks know what I might be doing wrong?

Thanks!


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2 thoughts on - SNMP Oddity

  • use

    net-snmp-config –default-mibdirs

    to locate where the mib file can be dropped so that snmp can use them. copy the mib file to one of the paths returned. mine usually end up in:

    /usr/share/snmp/mibs

    net-snmp-config –snmpconfpath

    To find the snmp config files

    Add the mib to the snmp.conf file. Mine looks like this:

    mibs +ALL
    mibs +ASTERISK-MIB
    mibs /usr/share/snmp/mibs/powernet419.mib

    you can simplify the line by looking at the mib file for this:

    PowerNet-MIB DEFINITIONS ::= BEGIN

    and then the config file can be this:

    mibs +ALL
    mibs +ASTERISK-MIB
    mibs +PowerNet-MIB

    To use the form above, the file has to be like this

    /usr/share/snmp/mibs/powernet419-mib.txt

    You can also use the MIBS environment variable to specify things:

    MIBS=+CISCO-RHINO-MIB:SOME-OTHER-SPIFFY-MIB
    export MIBS

  • I’d guess this is the raw string transported over the wire. The MIB likely translates to proper MAC formatting. `tcpdump’ should uncover this.

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