[SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [Q] [R] [S] [T] [U] [V] [W] [X] ! (exclamation point) escaping for shells excluding commands in sudoers file preventing file inclusion in Tripwire database "" (quotes, double), empty "any" interface "ring buffer" mode (for tethereal) $! variable (Perl), for system error messages %m format specifier to syslog to include system error messages 2nd . (period), in search path .gpg suffix (binary encrypted files) .shosts file / (slash), beginning absolute directory names /dev directory /dev/null, redirecting standard input from /proc files filesystems networking, important files for (/proc/net/tcp and /proc/net/udp) /sbin/ifconfig /sbin/ifdown /sbin/ifup /tmp/ls (malicious program) /usr/share/ssl/cert.pem file /var/account/pacct /var/log/lastlog /var/log/messages /var/log/secure unauthorized sudo attempts, listing /var/log/utmp /var/log/wtmp : (colons), current directory in empty search path element @ character, redirecting log messages to another machine @otherhost syntax, syslog.conf ~/.ssh directory, creating and setting mode ~/.ssh/config file |