All explained here:<br> http://www.debian-administration.org/articles/117 <br>

All Default Logs are configured via this Conf file:<br> /etc/syslog.conf

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:

http://www.aboutdebian.com/syslog.htm