Index

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# Index: U

U.S. Department of Energy : F.3.4.12. France: universities, Ministry of Research and Education in France, CNRS, CEA, INRIA, CNES, INRA, IFREMER, and EDF
U.S. Department of the Navy : F.3.4.44. U.S. Department of the Navy
U.S. law : (see laws)
U.S. Secret Service
  26.2.2. Federal Jurisdiction
  F.3.3. U.S. Secret Service (USSS)
UDP (User Datagram Protocol)
  16.2.4.3. UDP
  17.1.3. The /etc/inetd Program
  (see also network services)
  packet relayer : E.4.15. UDP Packet Relayer
ufsdump : (see dump/restore program)
UIDs (user identifiers)
  4.1. Users and Groups
  4.1.2. Multiple Accounts with the Same UID
  real versus effective
    4.3.1. Real and Effective UIDs
    C.1.3.2. Process real and effective UID
  RPC requests and : 19.2.2.2. AUTH_UNIX
  su command and : 10.1.2.1. su command and /etc/utmp and /var/adm/wtmp files
  of web servers : 18.2.1. The Server's UID
  zero : (see root account; superuser)
UK Defense Research Agency : F.3.4.37. UK: Defense Research Agency
ulimit command : 25.2.5. Soft Process Limits: Preventing Accidental Denial of Service
Ultrix : 1.3. History of UNIX
  trusted path : 8.5.3.1. Trusted path
  UUCP : 15.4.1.3. Format of USERFILE entry without system name
umask
  5.3. The umask
  5.3.2. Common umask Values
  8.4.3. Finding Dormant Accounts
unattended terminals
  12.3.5. Unattended Terminals
  12.3.5.2. X screen savers
uninterruptable power supply (UPS)
  2.2. Risk Assessment
  12.2.1.1. Fire
Unisys : F.3.4.39. UK: other government departments and agencies
universes : 5.9.1. Dual Universes
UNIX : 1. Introduction
  add-on functionality of : 1.4.3. Add-On Functionality Breeds Problems
  conventional passwords : 3.2.6. Conventional UNIX Passwords
  DAC (Discretionary Access Controls) : 4.1.3. Groups and Group Identifiers (GIDs)
  DNS under : 16.2.6.1. DNS under UNIX
  encryption programs for
    6.6. Encryption Programs Available for UNIX
    6.6.3.6. PGP detached signatures
  filesystem
    5. The UNIX Filesystem
    5.10. Summary
  history of : 1.3. History of UNIX
  modems and
    14.5. Modems and UNIX
    14.5.3.3. Privilege testing
  networking and : 16.1.2. Networking and UNIX
  operating systems : (see operating systems)
  primary network services
    17.3. Primary UNIX Network Services
    17.3.23. Other TCP Ports: MUDs and Internet Relay Chat (IRC)
  process scheduler : C.1.3.3. Process priority and niceness
  processes : (see processes)
  programming references : D.1.11. UNIX Programming and System Administration
  published resources for : D.1. UNIX Security References
  security and
    1.4. Security and UNIX
    1.4.3. Add-On Functionality Breeds Problems
  signals : C.3. Signals
  starting up
    C.5. Starting Up UNIX and Logging In
    C.5.3. Running the User's Shell
  Version 6 : 1.3. History of UNIX
  viruses : (see viruses)
  web server on : 18.2. Running a Secure Server
unlinked files : 25.2.2.7. Hidden space
unowned files : 24.4.1.8. Unowned files
unplugging connections : 24.2.5. Getting Rid of the Intruder
unpredictability of randomness : 23.6. Tips on Generating Random Numbers
upgrades, logging : 10.7.2.1. Exception and activity reports
uploading stored information : 12.3.4. Protecting Local Storage
UPS (uninterruptable power supply)
  2.2. Risk Assessment
  12.2.1.1. Fire
uptime command : 8.1.3. Accounts That Run a Single Command
urandom device : 23.7.4. Other random number generators
Usenet
  17.3.13. Network News Transport Protocol (NNTP) (TCP Port 119)
  E.2. Usenet Groups
  (see also NNTP)
  cleanup scripts : 11.5.3. Abusing Automatic Mechanisms
  encryption for : (see ROT13 algorithm)
  posting breakins to : 24.6. Resuming Operation
  reporting security holes on : 2.5.1. Going Public
User Datagram Protocol (UDP) : 16.2.4.3. UDP
user error : 7.1.1.1. A taxonomy of computer failures
user IDs : (see UIDs)
USERFILE file (UUCP)
  15.4.1. USERFILE: Providing Remote File Access
  15.4.2.1. Some bad examples
usermod command
  -e option : 8.4.3. Finding Dormant Accounts
  -f option : 8.4.3. Finding Dormant Accounts
  -s option : 8.3. Restricting Logins
usernames : 3.1. Usernames
  aliases for : 8.8.9. Account Names Revisited: Using Aliases for Increased Security
  doubling as passwords (Joes) : 3.6.2. Smoking Joes
  last command and : 10.1.3. last Program
  as passwords : 8.8.3.1. Joetest: a simple password cracker
  special
    4.2. Special Usernames
    4.2.3. Impact of the /etc/passwd and /etc/group Files on Security
  using someone else's
    4.3. su: Changing Who You Claim to Be
    4.3.8. Other Uses of su
users
  4. Users, Groups, and the Superuser
  4.1. Users and Groups
  4.1.2. Multiple Accounts with the Same UID
  (see also groups; su command)
  assigning passwords to : 8.8.1. Assigning Passwords to Users
  auditing who is logged in
    10.1.2. utmp and wtmp Files
    10.1.2.1. su command and /etc/utmp and /var/adm/wtmp files
  authentication for Web : 18.3.3. Setting Up Web Users and Passwords
  becoming other
    4.3. su: Changing Who You Claim to Be
    4.3.8. Other Uses of su
  checklist for : A.1.1.2. Chapter 3: Users and Passwords
  dormant accounts and
    8.4. Managing Dormant Accounts
    8.4.3. Finding Dormant Accounts
  identifiers for : (see UIDs)
  importing to NIS server
    19.4.1. Including or excluding specific accounts:
    19.4.4.2. Using netgroups to limit the importing of accounts
  letting in threats : 11.4. Entry
  limited : 8.1.5.1. Limited users
  logging
    10.4. Per-User Trails in the Filesystem
    10.4.3. Network Setup
  NIS passwords for : 19.3.2.1. Creating passwords for users
  nobody (Secure RPC) : 19.3.2.1. Creating passwords for users
  notifying about monitoring : 26.2.6. Other Tips
  proving identity of : 19.3.1.1. Proving your identity
  recognizing as intruders
    24.2. Discovering an Intruder
    24.2.6. Anatomy of a Break-in
  restricting certain : 18.3. Controlling Access to Files on Your Server
  root : (see root account; superuser)
  sending messages to : 10.5.1. The syslog.conf Configuration File
  summarizing system usage by : 25.2.2.2. quot command
  tainting : 18.2.3.4. Tainting with Perl
  training : 13.2.1. Initial Training
  UIDs : (see UIDs)
  unattended terminals
    12.3.5. Unattended Terminals
    12.3.5.2. X screen savers
  USERFILE entries for : 15.4.1.2. USERFILE entries for local users
  www : 18.2.2. Understand Your Server's Directory Structure
users command
  10.1.2. utmp and wtmp Files
  24.2.1. Catching One in the Act
USG (UNIX Support Group) : 1.3. History of UNIX
/usr directory
  4.3.7. The Bad su Log
  (see also /var directory)
  backing up /usr/bin : 7.1.2. What Should You Back Up?
  /usr/adm directory : 11.5.3.6. Other files
  /usr/adm/lastlog file : 10.1.1. lastlog File
  /usr/adm/messages file : 10.2.3. messages Log File
  /usr/bin directory
    11.1.5. Viruses
    11.5.1.1. PATH attacks
  /usr/bin/uudecode : (see uudecode program)
  /usr/etc/yp/makedbm program : 19.4.4.1. Setting up netgroups
  /usr/lib/aliases file : 11.5.3.3. /usr/lib/aliases, /etc/aliases, /etc/sendmail/aliases, aliases.dir, or aliases.pag
  /usr/lib directory : 11.5.3.6. Other files
    in restricted filesystems : 8.1.5. Restricted Filesystem
  /usr/lib/preserve program : 5.5.3.2. Another SUID example: IFS and the /usr/lib/preserve hole
  /usr/lib/sendmail : (see sendmail)
  /usr/lib/uucp/Devices file : 14.5.1. Hooking Up a Modem to Your Computer
  /usr/lib/uucp directory
    15.4.2.1. Some bad examples
    15.5.2. Permissions Commands
  /usr/lib/uucp/L-devices file : 14.5.1. Hooking Up a Modem to Your Computer
  /usr/lib/uucp/L.cmds file : (see L.cmds file)
  /usr/lib/uucp/L.sys file : 15.3.3. Security of L.sys and Systems Files
  /usr/lib/uucp/Permissions file : (see Permissions file)
  /usr/lib/uucp/Systems file : 15.3.3. Security of L.sys and Systems Files
  /usr/lib/uucp/USERFILE file
    15.4.1. USERFILE: Providing Remote File Access
    15.4.2.1. Some bad examples
  /usr/local/bin : 1.1. What Is Computer Security?
  /usr/local/bin directory : 11.5.1.1. PATH attacks
  /usr/local/etc/http/logs directory : 10.3.5. access_log Log File
  /usr/local/lib directory : 11.5.3.6. Other files
  /usr/sbin/rexecd : (see rexec service)
  /usr/spool/cron/crontabs directory : 15.6.2. Automatic Execution of Cleanup Scripts
  /usr/spool/uucp directory : 15.1.4. How the UUCP Commands Work
  /usr/spool/uucppublic : (see uucppublic directory)
  /usr/ucb directory : 11.1.5. Viruses
utility programs : 1.2. What Is an Operating System?
utimes commandn : 24.5.1. Never Trust Anything Except Hardcopy
utmp file
  10.1.2. utmp and wtmp Files
  10.1.2.1. su command and /etc/utmp and /var/adm/wtmp files
  24.2.1. Catching One in the Act
  24.2.4. Tracing a Connection
uucheck program : 15.5.3. uucheck: Checking Your Permissions File
uucico program
  15.1.4. How the UUCP Commands Work
  15.3. UUCP and Security
  15.5.1.1. Starting up
uucp (user)
  4.1. Users and Groups
  4.2.2. Other Special Users
uucp command : 15.1.1. uucp Command
UUCP system
  4.1.2. Multiple Accounts with the Same UID
  14.5. Modems and UNIX
  15. UUCP
  15.9. Summary
  additional logins : 15.3.1. Assigning Additional UUCP Logins
  BNU
    15.2. Versions of UUCP
    15.5. Security in BNU UUCP
    15.5.3. uucheck: Checking Your Permissions File
  checklist for : A.1.1.14. Chapter 15: UUCP
  cleanup scripts
    11.5.3. Abusing Automatic Mechanisms
    15.6.2. Automatic Execution of Cleanup Scripts
  early security problems : 15.7. Early Security Problems with UUCP
  HoneyDanBer (HDB) : 15.2. Versions of UUCP
  logging : 10.3.4. uucp Log Files
  mail forwarding : 15.6.1. Mail Forwarding for UUCP
  naming computer : 15.5.2. Permissions Commands
  over networks : 15.8. UUCP Over Networks
  NFS server and : 15.3. UUCP and Security
  passwords for : 15.3.2. Establishing UUCP Passwords
  Taylor : 15.2. Versions of UUCP
  over TCP : 17.3.20. UUCP over TCP (TCP Port 540)
  Version 2
    15.2. Versions of UUCP
    15.4. Security in Version 2 UUCP
    15.4.3. L.cmds: Providing Remote Command Execution
uucpa account : 15.3.1. Assigning Additional UUCP Logins
uucpd program : 15.8. UUCP Over Networks
uucppublic directory
  15.1.1. uucp Command
  15.4.1.3. Format of USERFILE entry without system name
  15.5.2. Permissions Commands
uudecode program : 17.3.4.2. Using sendmail to receive email
uuencode program : 6.6.1.2. Ways of improving the security of crypt
uux command : 15.1.2. uux Command
  - (hyphen) option : 15.1.2. uux Command
  -r option : 15.1.4. How the UUCP Commands Work
uuxqt program : 15.4.1.3. Format of USERFILE entry without system name
uuxqtcmds files : 15.4.3. L.cmds: Providing Remote Command Execution

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