Re: running snmpwalk on all MIB tree

[Magnus F. <ma...@ly...>]

On Wed, 2009-09-16 at 21:25 -0500, EYRE Bernadette wrote:
> 
> Hello Dave and net-snmp Coders,
> 
> 
> I was under the impression that the snmpwalk command, given the root
> oid, it will walk entire tree.
> Is this true?

No, as you have noticed.

> I'm running snmpwalk from a specfied MIB root node, say system.
> 
> I'm running net-snmp 5.4.2.1 version for Linux my snmpwalk command is:
> snmpwalk -Os -v 1 -c public localhost system
> and the result are:
> 
> 
> sysDescr.0 = STRING: "Linux cmm 2.6.29.6 #9 Thu Sep 10 11:44:52 PDT
> 2009 i686"
...
> sysORUpTime.8 = Timeticks: (1) 0:00:00.01
> 
> 
> I'm running the command from the same machine where the snmpd is
> running and MIBS and MIBDIRS env are set.
> 
> I started the snmpd with -f, -Dsnmp_agent and Lo options set to
> observe the behaviour.
> Here is my snmpd command:
> 
> /sbin/snmpd -f -Dsnmp_agent -V -a -c /usr/local/etc/snmp/snmpd.conf
> -x /var/agentx/master -Lo
> 
> Studying the trace it seems that snmpd stops when the start oid
> changes from what it was set before.

It is not snmpd who stops, it is snmpwalk that stop asking.

> Here is the tail end of the trace:
> 

> Received SNMP packet(s) from UDP: [127.0.0.1]->[127.0.0.1]:-13692
>   GETNEXT message
>     -- SNMPv2-MIB::sysORUpTime.8
> snmp_agent: agent_sesion 0x84b1ae8 created
> snmp_agent: add_vb_to_cache(0x84b1ae8, 1, SNMPv2-MIB::sysORUpTime.8, 0x805b478)
> snmp_agent: tp->start SNMPv2-MIB::sysORUpTime, tp->end SNMPv2-MIB::sysOREntry.5,
> snmp_agent: add_vb_to_cache(0x84b1ae8, 1, SNMPv2-MIB::sysORUpTime.8, 0x805b550)
> snmp_agent: tp->start SNMPv2-MIB::sysOREntry.5, tp->end IF-MIB::ifNumber,
> snmp_agent: add_vb_to_cache(0x84b1ae8, 1, SNMPv2-MIB::sysORUpTime.8, 0x80be228)
> snmp_agent: tp->start IF-MIB::ifNumber, tp->end IF-MIB::ifTable,
> snmp_agent: REMOVE session == 0x84b1ae8
> snmp_agent: agent_session 0x84b1ae8 released
> snmp_agent: end of handle_snmp_packet, asp = 0x84b1ae8

When snmpwalk get a return value that fails to match the original walue
it stops. This is what most snmpwalk programs do.

In the case of Net-SNMP you can, with a sufficiently new snmpwalk, give
the -CE <oid> option to explicitly give the oid after the last one that
interests you.

/MF