ufw logging LEVEL

LOGGING

ufw supports multiple logging levels. ufw defaults to a loglevel of
’low’ when a loglevel is not specified. Users may specify a loglevel
with:

ufw logging LEVEL

LEVEL may be ’off’, ’low’, ’medium’, ’high’ and full. Log levels are
defined as:

off disables ufw managed logging

low logs all blocked packets not matching the default policy (with
rate limiting), as well as packets matching logged rules

medium log level low, plus all allowed packets not matching the default
policy, all INVALID packets, and all new connections. All
logging is done with rate limiting.

high log level medium (without rate limiting), plus all packets with
rate limiting

full log level high without rate limiting

Loglevels above medium generate a lot of logging output, and may
quickly fill up your disk. Loglevel medium may generate a lot of
logging output on a busy system.

Specifying ’on’ simply enables logging at log level ’low’ if logging is
currently not enabled.

Reference : http://manpages.ubuntu.com/manpages/lucid/en/man8/ufw.8.html