A number of customers want to have some kind of external monitoring system for our appliances. SNMP is a fine choice, except that we do not enable it by default on our appliances, and we do not have a custom MIB. However, the SNMP daemon is installed, so if the customer knows what they're doing, it's just a matter of eenabling it.
 

SNMP is not included by default in App Layering (or Unidesk version 2 or 3).  For the rest of this article, whenever we say App Layering ELM, the same information also applies to the Unidesk MA and CachePoints.

To get it installed, your ELM will need Internet access.  Run this to download and install the package:

# yum install net-snmp
# yum install net-snmp-utils

If you have other mechanisms for downloading and installing net-snmp and net-snmp-utils, those are also acceptable, but see below for specifics.  "yum" is simply the most convenient method.

There is no App L ayering MIB, so all you can get from SNMP is the standard Linux performance counters.  Also, the default configuration does not contain security, so you ned to make sure you at least provide a community string to minimally secure the server.  All of the normal SNMP configuration options are available on the ELM, so you can configure and secure your instance however you need to.

Here's a recipe from a customer for installing SNMP on the ELM, where you have to download and configure SNMP yourself:

SSH via putty or another tool to the ELM.  

Login as: root
Password: set during initial configuration

# yum install net-snmp
answer Y to all questions
# yum install net-snmp-utils
answer Y to all questions

# snmpconf -g basic_setup
Select 1 or corresponding # to use this template: 1: /etc/snmp/snmpd.conf

Answer remaining questions as they pertain to your environment until complete.

Once you finish this run the following command to copy the snmpd.conf to the running location:

# cp ./snmpd.conf /etc/snmp/snmpd.conf
Select Y to overwrite

Then Run
# chkconfig snmpd on
# service snmpd start

Or reboot the ELM.

You may need to configure the firewall rules to allow traffic on ports 161 and 162 as well.  In the ELM, the commands are as follows (they are unnecessary on Unidesk V2/V3):

firewall-cmd --zone=public --add-port=161/udp --permanent
firewall-cmd --zone=public --add-port=161/tcp --permanent
firewall-cmd --zone=public --add-port=162/udp --permanent
firewall-cmd --zone=public --add-port=162/tcp --permanent
firewall-cmd --reload

Now you should be able to setup SNMP Monitoring as long as you filled out the configuration correctly.

If you do not have Internet access from the ELM or cannot run Yum in your environment, you will need to manually download and install the applicable RPM packages before starting the configuration above.  You will need the following four packages:

net-snmp-libs
net-snmp-agent-libs
net-snmp
net-snmp-utils

You can get them from any RedHat RPM mirror site, like http://mirror.as24220.net/pub/centos/7/updates/x86_64/Packages/.  Get those downloaded and copied into the ELM, using any SCP tool.  Then login as root, CD to the folder where you put the RPM files, and run the following (the exact package names may differ):

rpm -Uvh net-snmp-libs-5.7.2-33.el7_5.2.x86_64.rpm
rpm -Uvh net-snmp-agent-libs-5.7.2-33.el7_5.2.x86_64.rpm
rpm -Uvh net-snmp-5.7.2-33.el7_5.2.x86_64.rpm
rpm -Uvh net-snmp-utils-5.7.2-33.el7_5.2.x86_64.rpm

Then proceed with snmpconf as above.

Please note that net-snmp may state that it requires mysql-libs.  Although the exact package mysql-libs is not installed, the contents and capabilities of it are installed with the MySQL packages on the ELM.  If you are prompted by "yum" to install mysql-libs or mariadb-libs, say no.  You will then need to manually downlodad the RPM packages and proceed as below.  Unfortunately, yum does not have the ability to ignore a dependency.

If you are manually installing net-snmp from a downloaded RPM and it complains about needing mysql-libs, add the "--nodeps" parameter to the beginning of the rpm command line.

To test SNMP after installing and configuring it, assuming youcreated a read-only community string called "public", you can run this command:

snmpwalk -c public -localhost -v2c

If the SNMP daemon is running, you will get output.