Advanced Unix

1
Advanced Unix 25 Aug 05

• Understanding System Administration
• Chapter 10

2
Contents

• Root Login
• Admin Cmds
• Config Log Files
• GUI Admin Tools
• File System
• Monitoring
• Updates

3
Time Permitting

• File System
• Monitoring
• Updates

4
Definition of root su

• root (1) a file system term describing the top
  level directory of a drive or storage volume.
• root (2), or root access authorization within
  Unix-based operating systems that allows a user
  to make system-wide changes. This includes the
  ability to open and modify files that are
  off-limits to normal users, such as system files
  and and files within other users' home
  directories.
• super user (su) a user who has been given root
  access.

5
The root account

• Never login in as root
• It is dangerous
• There is no audit trail
• Always login with your personal account
• The su to root
• Disable root logins from the network
• Change the root password frequently
• Every 90 or 180 days for production servers

6
The Shell Prompt

• The command line prompt will indicate if you are
  logged in as root by displaying a before the
  cursor
• For System-V derivatives of UNIX you will see a
  if you are logged in as a normal user, if your
  are on a Berkeley derivative of UNIX

7
Examples that require root

• Adding, modifying deleting users from the
  system
• Changing and overriding user passwords
• Installing new programs and utilities
• Starting and stopping system services
• Setting up boot managers, such as GRUB and LILO
• Hardware and device driver configuration
• Mounting file systems
• Modifying system-level properties, such as
  network settings, web services, and e-mail
  configurations
• Performing remote reboots (may vary from system
  to system)

8
Changing a Password

• To Change the password of the account youre
  logged in as type the following
• passwd ltentergt
• To change the password of another user type the
  following
• passwd ltuseridgt
• For class you should change your password

9
Using the su command

• The su command allows one to become another user
  without logging off or to assume a role. The
  default user name is root (super user).
• To su to root type the following
• su
• To su to another user type the following
• su ltuseridgt

10
Administration Tools

• With FC3 the Sys Admin tools have the following
  syntax
• system-config-xxxx
• GUI Admin Tools
• Vary from Windows Manager
• Gnome
• KDE
• Etc

11
Sidebar Windows Mangers

• A window manager manages the different windows
  that appear on your screen
• Windows Placement
• Gidgets and Gadgets
• The overall Look and Feel of X-Windows
• Linux popular/common WMs
• Gnome
• KDE
• Fvwm
• AfterStep
• WindowMaker

12
Administration Commands

• Most system administration commands are locate in
  sbin directories such as
• /sbin
• /usr/sbin
• /usr/local/sbin

13
Administrative Config Files

• Most configuration files are located in the /etc
  directory
• /etc/passwd
• /etc/shadow
• /etc/mail/
• /etc/hosts
• /etc/fstab
• Etc/resolv.conf
• See pages 367-371

14
Administrative Log Files

• Most logs are located in /var/log directory
• /var/log/messages
• /var/log/lp
• /var/log/mail or /var/log/maillog
• /var/log/cron
• /var/log/wtmp

15
Limited root Access With sudo

• You can grant access to root commands to specific
  users using the sudo command
• Key files are
• /etc/sudoers
• /usr/sbin/visudo
• visudo - edits the sudoers file

16
(No Transcript)