The --short option limits the length of the log portion of barf's output, which can otherwise be extremely voluminous if debug logging is turned on.
Barf censors its output, replacing keys and secrets with brief checksums to avoid revealing sensitive information.
Beware that the output of both commands is aimed at humans, not programs, and the output format is subject to change without warning.
Barf has to figure out which files in /var/log contain the IPsec log messages. It looks for KLIPS and general log messages first in messages and syslog, and for Pluto messages first in secure, auth.log, and debug. In both cases, if it does not find what it is looking for in one of those ``likely'' places, it will resort to a brute-force search of most (non-compressed) files in /var/log.
/proc/net/* /var/log/* /etc/ipsec.conf /etc/ipsec.secrets
Finding updown scripts (so they can be included in output) is, in general, difficult. Barf uses a very simple heuristic that is easily fooled.
The brute-force search for the right log files can get expensive on systems with a lot of clutter in /var/log.