Comment 20 for bug 1246347

I'm still seeing this issue in Cosmic 18.10. It seems that, by default, snmpd is set to log at the DEBUG level which seems too intensive.

To fix I had to run the following (where "LS4d" indicates LOG_WARNING) as per the snmpd man page info below. With the log level set at LOG_WARNING this also has the added bonus that the many "Connection from UDP: [IP]:PORT->[IP]:PORT" snmpd INFO messages are also not output to /var/log/syslog...

$ sudo sed -i "s|-Lsd|-LS4d|" /lib/systemd/system/snmpd.service
$ sudo systemctl daemon-reload
$ sudo systemctl restart snmpd.service

snmpd man page (https://linux.die.net/man/1/snmpcmd):
0 or ! for LOG_EMERG,
1 or a for LOG_ALERT,
2 or c for LOG_CRIT,
3 or e for LOG_ERR,
4 or w for LOG_WARNING,
5 or n for LOG_NOTICE,
6 or i for LOG_INFO, and
7 or d for LOG_DEBUG.