• http://www.linuxquestions.org/questions/linux-security-4/var-log-wtmp-72976/
• https://linux.die.net/man/5/wtmp

strings /var/log/wtmp | egrep -vi "^pts\/|^ts\/" | grep -P "[0-9_\-]+\.[0-9_\-]+\.[0-9_\-]+\.[0-9_\-]+" | sort | uniq
utmpdump /var/log/wtmp | less
/usr/lib/acct/fwtmp < /var/adm/wtmp > /tmp/abc.out # AIX

~~DISCUSSION~~