Redhat or Fedora Core:
/var/log/secure
# Mandrake, FreeBSD or OpenBSD:
/var/log/auth.log
# SuSE:
/var/log/messages
# Mac OS X (v10.4 or greater):
/private/var/log/asl.log
# Mac OS X (v10.3 or earlier):
/private/var/log/system.log
# Debian:
/var/log/auth.log