All explained here:
All Default Logs are configured via this Conf file:
A Special Log File called admin.log is setup to catch Important information such as Failed Logins etc.
Edit /etc/syslog.conf and include:
*.emerg /var/log/admin.log *.alert /var/log/admin.log *.crit /var/log/admin.log *.err /var/log/admin.log *.warn /var/log/admin.log
Information got from: