Re: Net-SNMP Python bindings

On Mon, Oct 13, 2014 at 5:53 PM, Eduardo Bragatto <[email protected]>
wrote:

> Hi,
>
> I just started experimenting with the Python bindings and I noticed a
> behaviour that looks like a bug when I’m using snmpwalk().
>
> This is under Net-SNMP 5.5.2 on CentOS 6, 64 bits and python 2.7.
>
> First I’ll show an example of everything working as expected:
>
>
> If I “walk” through an index, for example: IF-MIB::ifIndex
>
> — begins —
> import netsnmp
>
> oid = netsnmp.VarList(netsnmp.Varbind('IF-MIB::ifIndex'))
> s = netsnmp.Session(DestHost=‘myhost', Community=‘mycommunity', Version=2)
> s.walk(oid)
> — ends —
>
> I get the following output (debug enabled):
>
> $ python2.7 test.py
> netsnmp_walk: filling request: IF-MIB::ifIndex::10:0
> netsnmp_walk: filling response: ifIndex:1
> netsnmp_walk: filling response: ifIndex:2
> netsnmp_walk: filling response: ifIndex:3
> netsnmp_walk: filling response: ifIndex:4
> netsnmp_walk: filling response: ifIndex:5
>
> In that case, I get “tag” is the same for all returned OIDs, and “iid” is
> incrementing. The same behaviour happens if I use “UseNumeric” and
> “UseLongNames”:
>
> — begins —
> import netsnmp
>
> oid = netsnmp.VarList(netsnmp.Varbind('IF-MIB::ifIndex'))
> s = netsnmp.Session(DestHost=‘myhost', Community=‘mycommunity', Version=2)
> s.UseLongNames = 1
> s.UseNumeric = 1
> s.walk(oid)
> — ends —
>
> The output is:
>
> $ python2.7 test.py
> netsnmp_walk: filling request: IF-MIB::ifIndex::10:0
> netsnmp_walk: filling response: .1.3.6.1.2.1.2.2.1.1:1
> netsnmp_walk: filling response: .1.3.6.1.2.1.2.2.1.1:2
> netsnmp_walk: filling response: .1.3.6.1.2.1.2.2.1.1:3
> netsnmp_walk: filling response: .1.3.6.1.2.1.2.2.1.1:4
> netsnmp_walk: filling response: .1.3.6.1.2.1.2.2.1.1:5
>
>
>
> However, if instead of IF-MIB, I use Dell’s "MIB-Dell-10892” (without the
> MIB actually being installed, using numeric OID), here’s what I get:
>
> First, without “UseLongNames” and “UseNumeric”:
>
> — begins —
> import netsnmp
>
> oid =
> netsnmp.VarList(netsnmp.Varbind('.1.3.6.1.4.1.674.10892.1.1100.30.1.1.1'))
> s = netsnmp.Session(DestHost=‘myhost', Community=‘mycommunity', Version=2)
> s.walk(oid)
> — ends —
>
> Output:
>
> $ python2.7 test.py
> netsnmp_walk: filling request: .1.3.6.1.4.1.674.10892.1.1100.30.1.1.1::14:0
> __get_type_str:FAILURE(0)
> __get_type_str:FAILURE(0)
> netsnmp_walk: filling response: enterprises.674.10892.1.1100.30.1.1.1.1:
> __get_type_str:FAILURE(0)
> __get_type_str:FAILURE(0)
> netsnmp_walk: filling response: enterprises.674.10892.1.1100.30.1.1.1.2:
>
> Note that in this case, “tag” was merged with “iid” and “iid” was left
> blank, however, if I use “UseNumeric” and “UseLongNames”, it works as
> expected:
>
> — begins —
> import netsnmp
>
> oid =
> netsnmp.VarList(netsnmp.Varbind('.1.3.6.1.4.1.674.10892.1.1100.30.1.1.1'))
> s = netsnmp.Session(DestHost=‘myhost', Community=‘mycommunity', Version=2)
> s.UseLongNames = 1
> s.UseNumeric = 1
> s.walk(oid)
> — ends —
>
> $ python2.7 test.py
> netsnmp_walk: filling request: .1.3.6.1.4.1.674.10892.1.1100.30.1.1.1::14:0
> __get_type_str:FAILURE(0)
> __get_type_str:FAILURE(0)
> netsnmp_walk: filling response: .1.3.6.1.4.1.674.10892.1.1100.30.1.1.1:1
> __get_type_str:FAILURE(0)
> __get_type_str:FAILURE(0)
> netsnmp_walk: filling response: .1.3.6.1.4.1.674.10892.1.1100.30.1.1.1:2
>
>
> Has anyone else encountered this kind of behaviour? I’m willing to go
> through the “client_intf.c” and try to fix this, but I’d like to hear from
> people with a similar setup and/or more experience with the python bindings.
>

Without the MIB being loaded, how can you expect the manager to know what
is the object and what is the iid?  If anything, it sounds like it's a bug
that the iid is filled in in any scenario without a MIB to support it.

  Bill

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