You can install Net-SNMP in Centos with the command:
sudo yum install net-snmp-utils net-snmp
In Ubuntu / Debian like this:
sudo apt install snmp snmpd
Make a copy of the standard configuration file just in case:
sudo mv /etc/snmp/snmpd.conf /etc/snmp/snmpd.conf.default
Next, for example, in the nano text editor open the configuration (Ctrl+X to exit, y/n to save or cancel changes):
sudo nano /etc/snmp/snmpd.conf
And open access to snmp for localhost and the specified subnet (where public is a community, rocommunity defines read-only access, rwcommunity reads and writes):
rocommunity public localhost
rocommunity public 192.168.1.0/24
Restart snmpd to apply the configuration changes:
sudo service snmpd restart
Run the test from the local server or the above subnet:
snmpwalk -v 1 -c public 127.0.0.1
See also my articles:
Installing MIB in Ubuntu and Solving the Error “SNMP Cannot Find Module …”
Linux snmp OIDs