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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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