encrypted password good passwords s group logins group permissions local area networks local machine ~zen local machine bad passwords login name login time passwd c password file permission bits physical disk remote execution remote machine restricted shell special file su c super-user privileges system administrator user education s .profile files f /bin c /bin/su c /dev/kmem c /dev/mem c /usr/bin c /usr/spool/uucppublic c chmod c chown c crypt c ct c cu c ls c mail c mode ~modern pack S super-user s ps c root set-userid facility sulog c umask c uucp C uux c %put c %take c System Security g Password Security Files And File Systems SUID Programs Trojan Horses Networking Encrypted File Misguided Efforts Logging su activity Password aging Recording unsuccessful login attempts Disabling accounts based on unsuccessful logins People s Users' Concerns s PATH variables s