Setting up SNMP V3 on CentOS

Install SNMP.

yum install net-snmp net-snmp-utils

Configure the SNMP V3 user by running the following command and then following the prompts it gives you.

net-snmp-create-v3-user

Example: The username is “snmpadmin” and the password is”r123456″

[root@localhost ~]# net-snmp-create-v3-user
Enter a SNMPv3 user name to create:
snmpadmin
Enter authentication pass-phrase:
r123456
Enter encryption pass-phrase:
  [press return to reuse the authentication pass-phrase]

adding the following line to /var/lib/net-snmp/snmpd.conf:
   createUser snmpadmin MD5 "r123456" DES
adding the following line to /etc/snmp/snmpd.conf:
   rwuser snmpadmin
[root@localhost ~]#

Change the syslocation and syscontact in the /etc/snmp/snmpd.conf file.

vi /etc/snmp/snmpd.conf

Start snmpd service

service snmpd start

Configure snmp to start on system boot.

chkconfig snmpd on

Test and make sure snmp is working

replace “password” and “username” with the ones you setup when you created the SNMP V3 user.

snmpwalk -v3 -a MD5 -A password -x DES -X password -l authPriv -u privuser localhost

If you receive something like “snmpwalk: Timeout” then something is not working correctly.  Check to make sure the service is started, and make sure that your firewall is not blocking SNMP.

If you are running a firewall, run the following commands to allow it through.

firewall-cmd --zone=public --add-port=161/udp --permanent
semanage port -a -t snmp_port_t -p udp 161
firewall-cmd --reload

On iptables you should be able to do

 iptables -A INPUT -p tcp -m state --state NEW -m tcp --dport 161 -j ACCEPT

or add it to /etc/sysconfig/iptables and then restart iptables

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