id -u is in the POSIX and LSB specs 1, while whoami is not.
Furthermore, the username of UID 0 can be changed (and is sometimes
recommended in a misguided attempt to increase security).
FreeBSD users logged in as toor would also slip through the cracks.
Replace "whoami" call with call to "id"
Log messages when a server connects or disconnects. Closes #781.