Linux Administration

1
Linux Administration
2
Pre-Install

• Different distributions
• Redhat, Caldera, mandrake, SuSE, FreeBSD
• Redhat Server Install
• Check HCL
• Significant issues
• Stability, availability and performance
• Avoid games, casual users, anonymous ftp, telnet
• Allow access via secure shell, secure ftp and
  firewall policies
• Avoid Xwindows unless needed by user at console
• Watch out - runaway daemons will eat your cpu

3
More pre-install options

• Dual-booting
• Need separate partitions for all OS you plan to
  run
• Fips.exe for repartitioning FAT
• Install windows First, Linux afterwards
• Install Options
• CDRom (boot.img) or over the net (bootnet.img)
• If install fails
• Kernel panic
• You dont need to panic !
• Its almost always Hardware issues.
• Check cdrom for CRC errors
• Check HCL

4
Installation

• Boot.img
• For CDROM install
• Type text for text based screen
• Hit enter for GUI based (If video card is pretty
  decent)
• Select language, keyboard and mouse
• To Reconfigure
• /usr/sbin/kbdconfig (keyboard) /usr/sbin/mouseconf
  ig (mouse)

5
Creating Partitions

• Partitions are mounted at boot time
• / is the root directory
• Common partitions
• /usr
• For program files
• /home
• Home directories for users
• /var
• Log files and system messages
• /tmp
• Temporary files. Monitor to avoid, filling up the
  entire hd
• Swap
• Not a file-system. Used as virtual storage and
  paging
• Double the RAM if less 128Mb or same as RAM is
  more than 128Mb.

6
Boot Manager

• Handles the actual load process of the OS
• Same as NTLDR (windows NT)
• LILO
• GRUB
• Where to setup the boot manager ?
• MBR (Master Boot Record)
• BIOS uses POST for hardware checking and passes
  control to MBR.
• The software in MBR is loaded
• First sector of the boot partition
• Select this if you are using another boot loader
• Preferred boot loader runs first and passes
  control to LILO/GRUB if you decide to start
  linux.
• LBA (Logical Block Addressing)
• Used by SCSI devices

7
Network Config and User List

• Ethernet cards are numbered
• eth0, eth1, eth2
• Configurable as DHCP or static
• User list
• /etc/passwd
• Cannot login unless the user has an entry
• NIS for remote user authentication
• /etc/shadow
• Encrypted passwd file
• Supports long passwords upto 256 char
• Supports different encryptions
• MD5, blowfish

8
Configuring X

• X Windows
• Basis of linux gui
• Communicates with the actual video hardware.
• Numerous programs that use X
• KDE, GNOME, Enlightenment, Sawfish
• Decoupled from the base OS
• Possible to load OS with out starting the GUI
• Saves memory and system resources
• Xorg
• Version of X used by linux.
• Xfree86 (older version)
• Auto detects video card and monitor
• Manual configuration if card is not identified
• Requires user to know frequency monitor, refresh
  rates, memory on video card.

9
Common Commands

• linuxconf
• For most administrative tasks
• Manage users, passwords, network configurations,
  devices
• ps ef grep more
• See all running processes.
• kill
• Kill a running process (kill -9 254)
• man
• Documentation (man ls)
• ls (folder, file listing)
• chgrp (change group)
• chown (change ownership)- p384 for permissions
• gzip, tar (to compress files)
• du (disk utilization)

10
Useful Commands

• Su (switch user)
• Change user
• Uptime
• Tells how long the system has been up.
• Xconfigurator (redhat 8 or lower)
• redhat-config-xfree86 (redhat 9)
• Configure display
• Mouseconfig
• Configure mouse
• Setup
• Fire wall, ports, display manager, audio