Linux Security Cookbook
| [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] UDP blocking packets on privileged ports probing ports, difficulties of stateful firewall, necessity for testing for open port umask Linux chmod and umask commands preventing files from being world-writable setting as group writable unicast packets unique identifier for GnuPG keys unsecured IMAP connections unshadow command urlsnarf command Usenet news, tunneling NNTP connections through SSH user (inetd.conf file) user accounts allowing one account to access another with ksu multiple root accounts without a password, finding restricting access to SSH server by restricting hostbased authentication to for SMTP authentication superuser, finding suspicious use, checking for on multiple systems usernames in remote file copying usernames in trusted-host authentication user facility, system messages user ID of zero (0) (superuser) users administration of their own machines authorizing to restart sshd changes since last Tripwire check Kerberos credentials for login information about, printing script forcing sudo to prompt for password |