How To Configure SNMP Logging on RHEL 7

Overview

In this guide we will go over different SNMP logging facility configuration on a Linux based operating system.

We will also go over different SNMPD startup options as per the business / IT Operations requirements.

We will also get to know as to  how we can configure logging levels based on the "Logging Facility" and when to utilize it.

Applies To

• Ubuntu
• RHEL 6.5
• RHEL 7

Pre-Requisites

• Net-SNMP packages are installed on the server.

SNMP Daemon – Configuration File – Startup Options

Listed below is the configuration file “snmpd.conf” location on different operating systems.

Operating System	File Location
Ubuntu	/etc/default/snmpd
RHEL / CentOS	/etc/sysconfig/snmpd

SNMP Daemon – Configuration File – View

Once you configure the snmp daemon startup options you can also validate / view configuration by running the below command;

On Ubuntu – run the command;

lsb_release -d
cat /etc/default/snmpd | grep SNMPDOPTS

On RHEL / CentOS – run the command;

cat /etc/redhat-release
cat /etc/sysconfig/snmpd | grep OPTIONS

SNMP Daemon – Configuration File – Reconfiguration

In case the default / custom configuration file is missing or corrupted, you can recreate a new snmp.conf configuration file; to reconfigure / re-create run the command below;

snmpconf

With this command you can also reconfigure / create new configuration file(s); When you run the command, it will read the current configuration file;

1. /etc/snmp/snmp.conf
2. /etc/snmp/snmpd.conf
3. /etc/snmp/snmptrapd.conf

Upon re-configuring is done with “snmpconf” command; you can perform these actions;

• overwrite
• rename
• append
• skip

SNMP Daemon – Startup Options

By default, SNMP daemon is started with the configuration file “/etc/default/snmpd”, “/etc/sysconfig/snmp” in Ubuntu, RHEL OS respectively with startup options as below;

# RHEL OS

cat /etc/sysconfig/snmp
# OPTIONS="-LS0-6d"

# Ubuntu OS

cat /etc/default/snmpd
SNMPDOPTS='-Lsd -Lf /dev/null -u snmp -I -smux -p /var/run/snmpd.pid -g root 0.0.0.0'

Startup Options Purpose

SNMP daemon startup attribute(s) purpose are shown below table.

Options	Purpose
L	Logging
S	Syslog
D	Daemon
-Ls	Log messages via syslog
-Lf	Log messages to the specified file
U	User
I	Initialize
smux	SNMP Multiplexing Protocol (disabled by default)
P	Process ID
G	Group ID

Syslog Daemon Options

Syslog daemon startup can be configured with different options, few of them are listed in the below table;

Logging Options	Purpose
-Lsd	Log Syslog Daemon (default)
-Lsd	Log Syslog Warning Message
-LSwd or -Ls4d	Log Syslog Error Message
-Lf /dev/null	Redirect to Null file

Logging Facility Table

Table below gives logging facility that can be configured.

Numeric Value	Character Value	Log Type	Logging Scenario / Purpose
0	!	LOG_EMERG	Emergencies – System is unusable
1	a	LOG_ALERT	Alerts – Immediate action needed
2	b	LOG_CRIT	Critical – Critical conditions
3	c	LOG_ERR	Error – Error conditions
4	e	LOG_WARNING	Warnings – Warning conditions
5	n	LOG_NOTICE	Notifications – Informational messages
6	i	LOG_INFO	Informational – Normal but significant conditions
7	d	LOG_DEBUG	Debug – Debugging messages

SNMP Daemon Management

To manage snmpd daemon, run the command based on the SysVinit or Service Manager enabled on the server(s);

SysVinit Enabled OS	Systemd Enabled OS
service snmpd start	systemctl start snmpd
service snmpd stop	systemctl stop snmpd
service snmpd restart	systemctl restart snmpd
service snmpd status	systemctl status snmpd

Managing SNMPD Daemon

SNMP Daemon – Start

To start snmpd daemon, run the command;

systemctl start snmpd

SNMP Daemon – Stop

To stop snmpd daemon, run the command;

systemctl stop snmpd

SNMP Daemon – Restart

To restart snmpd daemon, run the command;

systemctl restart snmpd

SNMP Daemon – Status

To know the stuats of snmpd daemon, run the command;

systemctl status snmpd

Slideshare Info

A step by step guide with screenshots is uploaded to slideshare.

How To Configure SNMP Logging on RHEL 7 from VCP Muthukrishna