[SOLVED] how to get modified output from 'snmpwalk' command

rohitchauhan · 02-11-2014, 02:08 AM

Hi guys,
I was trying SNMP monitoring in my linux system. I installed and configured the required package. Then I run the following command to get the memory status:

[root@nagios ~]# snmpwalk -c public -v 2c localhost memory
UCD-SNMP-MIB::memIndex.0 = INTEGER: 0
UCD-SNMP-MIB::memErrorName.0 = STRING: swap
UCD-SNMP-MIB::memTotalSwap.0 = INTEGER: 4030456 kB
UCD-SNMP-MIB::memAvailSwap.0 = INTEGER: 4030456 kB
UCD-SNMP-MIB::memTotalReal.0 = INTEGER: 3890484 kB
UCD-SNMP-MIB::memAvailReal.0 = INTEGER: 1750044 kB
UCD-SNMP-MIB::memTotalFree.0 = INTEGER: 5780500 kB
UCD-SNMP-MIB::memMinimumSwap.0 = INTEGER: 16000 kB
UCD-SNMP-MIB::memBuffer.0 = INTEGER: 128844 kB
UCD-SNMP-MIB::memCached.0 = INTEGER: 1038836 kB
UCD-SNMP-MIB::memSwapError.0 = INTEGER: noError(0)
UCD-SNMP-MIB::memSwapErrorMsg.0 = STRING:

Now, my requirement is that I want the SNMP output to show the figure "2850" from the second line. Or if possible some kind of edited (or tweaked) output i.e. (1710+125+1014=2849).

[root@nagios ~]# free -m
total used free shared buffers cached
Mem: 3799 2088 1710 0 125 1014
-/+ buffers/cache: 948 2850
Swap: 3935 0 3935

In a line, I want SNMP to reflect the output 2850 by command.

Is there a way to do this ?
Is there a way to tweak the output of snmpwalk command ?
Is there a way to achieve this in another fashion ?

Thanks in advance.

Note: Also please tell me best practices of posting a question here. I think there is a way of highlighting the command and output in my question.

Nephew · 02-11-2014, 06:00 AM

We do it like this:
Create a script that will be called by snmpd to get that value. Lets call it /usr/local/bin/getmem.sh

Code:

#!/bin/bash
free -m|egrep 'buffers\/cache' | awk '{print $4}'

Run this script manually to make sure it echo the value you are looking for.

Now change your snmpd.conf and add a entry like this:

Quote:

extend .1.3.6.1.4.1.12345.123.1 mem2 /usr/local/bin/getmem.sh

Restart snmpd
Now run snmpwalk with the oid to see which output is the one that is needed

Code:

snmpwalk -c public -v 2c localhost 1.3.6.1.4.1.12345.123.1

rohitchauhan · 02-15-2014, 06:17 AM

Hi,
Thanks for your solution. It worked for me perfectly.

NOW I have 1 more query. When I run the command:

Code:

# snmpwalk -c public -v 2c localhost 1.3.6.1.4.1.12345.123.1
# snmpwalk -c public -v 2c 127.0.0.1 1.3.6.1.4.1.12345.123.1

Both commands run successfully.

But when I run the command with IP address:

Code:

# snmpwalk -c public -v 2c 192.168.1.71 1.3.6.1.4.1.12345.123.1

It says:
Timeout: No Response from 192.168.1.71

I am not sure where should I look for it in configuration.

Can you please suggest something.

Thanks.

Nephew · 02-15-2014, 01:58 PM

SNMPD is probably not listening on all interfaces, just on localhost.

On my distro(Slackware) to listen on the interface and on localhost I can run it like this:

Quote:

/usr/sbin/snmpd -c /etc/snmp/snmpd.conf 127.0.0.1 192.168.1.71

Habitual · 02-15-2014, 02:18 PM

Linux SNMP OID’s for CPU,Memory and Disk Statistics

Hope that's helpful.

rohitchauhan · 02-18-2014, 01:37 AM

Hi Nephew,
I did run the command as you mentioned and here is what happened with me:

Code:

[root@client ~]# /usr/sbin/snmpd -c /etc/snmp/snmpd.conf 127.0.0.1 192.168.1.71
[root@client ~]# echo $?
1

Looks like something is wrong.

Well I will look into that as soon as I get sufficient time.

But meanwhile, can you please tell me one more thing, that How can I get the OID of any of the below parameter (by using its name or string i.e. memTotalSwap.0) ?

Example:
"UCD-SNMP-MIB::memIndex.0 = INTEGER: 0
UCD-SNMP-MIB::memErrorName.0 = STRING: swap
UCD-SNMP-MIB::memTotalSwap.0 = INTEGER: 4030456 kB
UCD-SNMP-MIB::memAvailSwap.0 = INTEGER: 4030456 kB
UCD-SNMP-MIB::memTotalReal.0 = INTEGER: 3890484 kB"

To find the OID, I used run the command:

Code:

# snmptranslate -Td -IR memTotalSwap.0

UCD-SNMP-MIB::memTotalSwap.0
memTotalSwap OBJECT-TYPE
  -- FROM       UCD-SNMP-MIB
  SYNTAX        Integer32
  UNITS         "kB"
  MAX-ACCESS    read-only
  STATUS        current
  DESCRIPTION   "The total amount of swap space configured for this host."
::= { iso(1) org(3) dod(6) internet(1) private(4) enterprises(1) ucdavis(2021) memory(4) memTotalSwap(3) 0 }

So this is not showing OID actually. Only some information.

Thanks.