SNMPD spamming /var/log/messages is a pet hate of mine. It causes so much rubbish to be sat in the logs. I had a hard time looking for how to do this on centos 7. I eventually managed to work it so im adding it here as i wasnt able to find the relevant resource online.
CD into the relevant directory
[root@home-server ~]# cd /etc/systemd/system/multi-user.target.wants
[root@home-server multi-user.target.wants]# vi snmpd.service
Change the Environment variable as so:
Restart the service
[root@home-server multi-user.target.wants]# systemctl restart snmpd.service
Say good bye to all these messages!
Apr 19 03:25:41 home-server snmpd: Connection from UDP: [192.168.*.*]:39604->[192.168.*.*]:161