SNMP

SNMP is among the blackest of magical arts.

Changes to the configs are not committed until clean restart or SIGHUP!

v3 User Management

Create

net-snmp-create-v3-user -a <authmode> -A <authpass> -x <encrmode> -X <encrpass> <firstuser>
net-snmp-create-v3-user -a SHA-512 -A 12345678 -x AES128 -X 12345678 default

Clone

snmpusm -v3 -l priv -u <firstuser> -a <authmode> -A <authpass> -x <encrmode> -X <encrpass> localhost create <template>
snmpusm -v3 -l priv -u default -x SHA-512 -X 12345678 -a AES128 -A 12345678 localhost create template

snmpusm -v3 -l priv -u <template> -a <authmode> -A <authpass> -x <encrmode> -X <encrpass> localhost create <newuser> <clonefrom>
snmpusm -v3 -l priv -u template -x SHA-512 -X 12345678 -a AES128 -A 12345678 localhost create newuser template

Test

Add new users to /etc/snmp/snmpd.conf:
rouser <username>
rwuser <username>
snmpstatus -v3 -l priv -u <username> -a <authmode> -A <authpass> -x <encrmode> -X <encrpass> localhost

Change Passwords

Auth:
snmpusm -v3 -l priv -u <user> -a <authmode> -A <authpass> -x <encrmode> -X <encrpass> -Ca localhost passwd <oldauthpass> <newauthpass> <user>
Encr:
snmpusm -v3 -l priv -u <user> -a <authmode> -A <authpass> -x <encrmode> -X <encrpass> -Cx localhost passwd <oldencrpass> <newencrpass> <user>

Delete

snmpusm [auth options] localhost delete <targetuser>

v2c Communities

/etc/snmp/snmpd.conf:
rocommunity PASSPHRASE [SOURCE_IP]
rwcommunity PASSPHRASE [SOURCE_IP]

Take a Walk

snmpwalk -v2c -c PASSPHRASE TARGET_IP
snmpwalk -v3 -l priv -u <user> -a <authmode> -A <authpass> -x <encrmode> -X <encrpass> TARGET_IP

Custom Scripts

/etc/snmp/snmpd.conf

pass .1.3.6.1.2.1.25.1.10.4 /bin/sh /opt/snmp-smart-status_sda.sh
agentuser root

Debians: /lib/systemd/system/snmpd.service

ExecStart=-u root

/opt/snmp-smart-status_sda.sh

#!/bin/bash
if [ "$1" = "-g" ]
then
        echo .1.3.6.1.2.1.25.1.10.4
        echo string
        smartctl -H /dev/sda | grep "OK" | awk '{print $4}'
fi