Table of Contents for

Practical UNIX and Internet Security, 3rd Edition

U

U.S. Secret Service (USSS), U.S. Secret Service (USSS)

UDP (User Datagram Protocol), Packets and Protocols, UDP–UDP, The inetd Program, The TCP Wrappers configuration language, Domain Name System (DNS) (TCP and UDP Port 53), The NFS Protocol

(see also network services)

DNS and, Domain Name System (DNS) (TCP and UDP Port 53)

NFS protocol built on, The NFS Protocol

TCP Wrappers support for, The TCP Wrappers configuration language

UDP socket, Unix syslog

UFS (Unix File System), UFS and the Fast File System–Directories and links, The Virtual Filesystem Interface

ufsdump, Encrypting Your Backups (see dump program)

UIDs (user identifiers), Add-on Functionality Breeds Problems, Logging in with Usernames and Passwords, Users, Groups, and the Superuser, Users and Groups, User Identifiers (UIDs), User Identifiers (UIDs), The su Command: Changing Who You Claim to Be–sudo: A More Restrictive su, Real and Effective UIDs with the su Command, Inodes, SUID and SGID, The inetd Program, AUTH_UNIX, The su command and the utmp and wtmp files, Process real and effective UIDs

(see also SUID programs)

for superuser, User Identifiers (UIDs)

real versus effective, Real and Effective UIDs with the su Command, Process real and effective UIDs

and RPC requests, AUTH_UNIX

for server process, The inetd Program

stored in inodes, Inodes

su command and, The su command and the utmp and wtmp files

switching temporarily, The su Command: Changing Who You Claim to Be–sudo: A More Restrictive su

zero, Users, Groups, and the Superuser (see root account superuser)

ulimit command, Soft Process Limits: Preventing Accidental Denial of Service

Ultrix, The Unix Wars: Why Berkeley 4.2 over System V, Trusted path

umask, The umask–Common umask Values, Finding Dormant Accounts

UMNT request, The MOUNT Protocol

UMNTALL request, The MOUNT Protocol

unattended terminals, Unattended Terminals

Underground (Dreyfus, Suelette), Understanding the Computer Security “Culture”

underscore (_), in hostnames, Format of the hostname

Unicode, Directory Permissions

unintended disclosure and, Unintended Disclosure of Site Information with NIS

uninterruptable power supply, Fire (see UPS)

unison program, Network Backup Systems

United States, Federal jurisdiction, Federal Computer Crime Laws

federal computer crime laws, Federal Computer Crime Laws

federal jurisdiction, Federal jurisdiction

Universal Coordinated Time (UTC), NTP: Network Time Protocol (UDP Port 123)

Unix, Preface–Unix “Security”?, Preface–Unix “Security”?, Which Unix System?, Which Unix System?–“Secure” Versions of Unix, Which Unix System?, Versions Covered in This Book, Versions Covered in This Book, “Secure” Versions of Unix, Introduction: Some Fundamental Questions, What Is an Operating System?, What Is an Operating System?, What Is an Operating System?, What Is an Operating System?, What Is an Operating System?, What Is a Deployment Environment?–What Is a Deployment Environment?, What Is a Deployment Environment?, What Is a Deployment Environment?, What Is a Deployment Environment?, History of Unix–What the Future Holds, Free Unix–Businesses adopt Unix, What the Future Holds, Security and Unix–The Failed P1003.1e/2c Unix Security Standard, Add-on Functionality Breeds Problems–Add-on Functionality Breeds Problems, An Empirical Study of the Reliability of Unix Utilities–Where’s the beef?, Updating System Software–Sensitive Upgrades, Updating System Software, Starting Up Unix and Logging In–Running the User’s Shell, Unix Security References

(see also specific operating systems)

add-on functionality of, Add-on Functionality Breeds Problems–Add-on Functionality Breeds Problems

current trends, What the Future Holds

deployment environments using, What Is a Deployment Environment?–What Is a Deployment Environment?

free versions of, Free Unix–Businesses adopt Unix

history of, Preface–Unix “Security”?, Which Unix System?, Introduction: Some Fundamental Questions, History of Unix–What the Future Holds

installing new system, Updating System Software

kernel, What Is an Operating System? (see kernel)

mobile versions of, What Is a Deployment Environment?

open source, Versions Covered in This Book

parts of, What Is an Operating System?

published resources for, Unix Security References

secure versions of, “Secure” Versions of Unix

security and, Preface–Unix “Security”?, Security and Unix–The Failed P1003.1e/2c Unix Security Standard

security policy, What Is an Operating System? (see policy, security)

servers, What Is a Deployment Environment?

starting up, Starting Up Unix and Logging In–Running the User’s Shell

system database files, What Is an Operating System?

system software, updating, Updating System Software–Sensitive Upgrades

thin-client systems, What Is a Deployment Environment?

utilities, What Is an Operating System?, An Empirical Study of the Reliability of Unix Utilities–Where’s the beef?

versions covered in this book, Versions Covered in This Book

versions of, Which Unix System?–“Secure” Versions of Unix

Unix domain socket, Unix syslog

Unix File System, UFS and the Fast File System (see UFS)

The UNIX Programming Environment (Kernighan, Brian; Ritchie, Dennis; Pike, Rob), Unix Programming and System Administration

Unix Support Group (USG), Unix goes commercial

UNIX System Administration Handbook (Nemeth, Evi; Snyder, Garth; Seebass, Scott; Hein, Trent R.), Unix Programming and System Administration

UNIX System Security (Wood, Patrick H. and Kochan, Stephen G.), Unix Security References

Unix-to-Unix Copy System (UUCP), Modems and Unix

unowned files, Unowned files

unsecure, Trust

unshare command, Exporting NFS directories under System V: share and dfstab

upgrades, Upgrading Distributed Applications–Sensitive Upgrades, Upgrading Distributed Applications, Sensitive Upgrades, Exception and activity reports

backing out of, Upgrading Distributed Applications

logging, Exception and activity reports

sensitive, Sensitive Upgrades

UPS (uninterruptable power supply), Risk Assessment, Fire

uptime account, Accounts That Run a Single Command

urandom device, Picking a Random Seed

Usenet, Responsible Disclosure, Users and Groups, NNTP: Network News Transport Protocol (TCP Port 119), Usenet Groups

(see also NNTP)

groups, security-related, Usenet Groups

news user, Users and Groups

reporting security holes on, Responsible Disclosure

USENIX/SAGE Association, USENIX/SAGE

User Datagram Protocol, UDP (see UDP)

user IDs, Add-on Functionality Breeds Problems (see UIDs)

usermod command, Restricting Logins, Finding Dormant Accounts, Finding Dormant Accounts

-e option, Finding Dormant Accounts

-f option, Finding Dormant Accounts

-s option, Restricting Logins

usernames, Logging in with Usernames and Passwords–Unix Usernames, Smoking Joes, Any Username Can Be a Superuser, The su Command: Changing Who You Claim to Be–sudo: A More Restrictive su, Joetest: a simple password cracker, Account Names Revisited: Using Aliases for Increased Security

aliases for, Account Names Revisited: Using Aliases for Increased Security

doubling as passwords (Joes), Smoking Joes, Joetest: a simple password cracker

for superuser, Any Username Can Be a Superuser

switching temporarily, The su Command: Changing Who You Claim to Be–sudo: A More Restrictive su

users, Add-on Functionality Breeds Problems, Policies and Guidelines, Types of Security, Steps in Risk Assessment, Identifying threats, Identifying threats, Convincing Management, Concentrate on education, Defend in depth, The Problem with Security Through Obscurity, Authenticating Users–Entering your password, Users and Groups–User Identifiers (UIDs), Users and Groups, Users and Groups, The su Command: Changing Who You Claim to Be–sudo: A More Restrictive su, Personnel Security–Summary, Ongoing Training and Awareness, Auditing Access, Trusted hosts and users, Creating passwords for users, Creating passwords for users, Including or excluding specific accounts, Using netgroups to limit the importing of accounts, The Role of Backups, Replace tapes as needed, Assigning Passwords to Users–Assigning Passwords to Users, The syslog.conf configuration file, Unix Forensics–Network Setup, Discovering an Intruder–Getting Rid of the Intruder, Monitoring commands, Authors, quot command, Chapter 4: Users, Passwords, and Authentication, Chapter 5: Users, Groups, and the Superuser

(see also employees; groups; superuser)

accidentally deleting files, The Role of Backups

assigning passwords to, Assigning Passwords to Users–Assigning Passwords to Users

auditing equipment access of, Auditing Access

auditing system activity of, Types of Security

authenticating, Authenticating Users–Entering your password

backup errors of, Replace tapes as needed

effects of obscurity on, The Problem with Security Through Obscurity

identifiers for, Add-on Functionality Breeds Problems (see UIDs)

importing to NIS server, Including or excluding specific accounts, Using netgroups to limit the importing of accounts

as intruders, Discovering an Intruder–Getting Rid of the Intruder

logging, Unix Forensics–Network Setup

monitoring, Monitoring commands

NIS passwords for, Creating passwords for users

nobody, Users and Groups, Creating passwords for users

participation in security policy, Steps in Risk Assessment

power users, Convincing Management

security awareness of, Policies and Guidelines, Concentrate on education, Defend in depth, Ongoing Training and Awareness

security checklist for, Chapter 4: Users, Passwords, and Authentication, Chapter 5: Users, Groups, and the Superuser

security regarding, Personnel Security–Summary

security threats caused by, Identifying threats, Authors

sending messages to, The syslog.conf configuration file

summarizing filesystem usage by, quot command

switching temporarily, The su Command: Changing Who You Claim to Be–sudo: A More Restrictive su

system, Users and Groups

trusted, Trusted hosts and users

users command, Examining the utmp and wtmp files, Monitoring commands

USG (Unix Support Group), Unix goes commercial

/usr directory, The su Log, An example of a SUID attack: IFS and the /usr/lib/preserve hole, Connecting a Modem to Your Computer, Connecting a Modem to Your Computer, SMTP: Simple Mail Transfer Protocol (TCP Port 25), Delivery to programs, rexec (TCP Port 512), Setting up netgroups, Viruses, Viruses, Other files, Other files, Other files

(see also /var directory)

/usr/adm directory, Other files

/usr/bin directory, Viruses

/usr/bin/uudecode, Delivery to programs (see uudecode program)

/usr/etc/yp/makedbm program, Setting up netgroups

/usr/lib directory, Other files

/usr/lib/preserve program, An example of a SUID attack: IFS and the /usr/lib/preserve hole

/usr/lib/sendmail, SMTP: Simple Mail Transfer Protocol (TCP Port 25) (see sendmail program)

/usr/lib/uucp/Devices file, Connecting a Modem to Your Computer

/usr/lib/uucp/L-devices file, Connecting a Modem to Your Computer

/usr/local/lib directory, Other files

/usr/sbin/rexecd, rexec (TCP Port 512) (see rexec service)

/usr/ucb directory, Viruses

USSS (U.S. Secret Service), U.S. Secret Service (USSS)

UTC (Universal Coordinated Time), NTP: Network Time Protocol (UDP Port 123)

utilities, Unix, What Is an Operating System?, An Empirical Study of the Reliability of Unix Utilities–Where’s the beef?

security vulnerabilities with, An Empirical Study of the Reliability of Unix Utilities–Where’s the beef?

standard, What Is an Operating System?

utimes() system call, Never Trust Anything Except Hardcopy

utmp file, Essential Log Files, utmp and wtmp Files–Pruning the wtmp file, Monitoring commands, Tracing a Connection

utmpx file, Essential Log Files

UUCP (Unix-to-Unix Copy System), Modems and Unix

uucp user, Users and Groups

uudecode program, Delivery to programs