by Aliaksandr Stelmachonak, Dzmitry Kuchko

® 2007. EPAM Systems. All rights reserved.

Delivering Excellence in Software Engineering


by Aliaksandr Stelmachonak, Dzmitry Kuchko

GNU/Linux FundamentalsPart 3

® 2007. EPAM Systems. All rights reserved. 2

Network Configuration


Network interface configurator

ifconfig – configure and control TCP/IP

network interfaces

Example:

Common uses for ifconfig include

• setting an interface's IP address and netmask

• and disabling or enabling a given interface

ifconfig

displaying the current state of network interfaces


Network interface configurator

ifconfig –a

ifconfig eth0

ifconfig eth0 up

ifconfig eth0 down

ifconfig eth0 inet 192.168.1.13 netmask 255.255.255.0

displaying the current state of eth0 interface

Setting configuration for eth0 interface

display all interfaces which are currently available, even if down

Activating and deactivating eth0 interface


Network commands

$ ping google.com

$ ping –c 5 google.com

$ traceroute google.com

$ tracepath ya.ru

$ host ya.ru

$ host 213.180.204.8

$ dig ya.ru

$ dig –x 213.180.204.8

sending a ping request

show the network route for a given host

translate ip address to hostname or vice versa

Another method


Slamd64MOPSLinuxZenwalkSUSE LinuxOpenSUSE Knoppix

XandrosLindows/Linspire/FreespireSimplyMEPISUbuntu Family

Red FlagYellow DogCentOSMandrake/MandrivaFedora

Linux distros hierarchy


/etc/sysconfig/network• /etc/sysconfig/

network-scripts/ifcfg-ethX

• /etc/sysconfig/network

• /etc/resolv.conf

Debian based

• /etc/network/interfaces

• /etc/hostname

• /etc/resolv.conf

Differences between distros

Red Hat based


[root@rhel ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0• DEVICE=eth0

• IPADDR=208.164.186.1

• NETMASK=255.255.255.0

• NETWORK=208.164.186.0

• BROADCAST=208.164.186.255

• ONBOOT=yes

•

root@ubuntu:~# cat /etc/network/interfaces

• auto lo eth0

• iface eth0 inet static

• address 192.168.0.10

• netmask 255.255.255.0

• gateway 192.168.0.1

Main Settings

BOOTPROTO=dhcp

dhcp


[root@rhel ~]# cat /etc/sysconfig/network• NETWORKING=yes

• FORWARD_IPV4=yes

• HOSTNAME=myhost.local

• GATEWAY=192.168.0.1

root@ubuntu:~# cat /etc/hostname• myhost.local

• ;-)

Host name


root@generic-linux:~# cat /etc/resolv.conf• domain minsk.epam.com

• search epam.com. minsk.epam.com.

• nameserver 10.6.0.6

• nameserver 10.6.0.16

DNS and search domains


root@ubuntu:~# /etc/init.d/networking restart

* Reconfiguring network interfaces... [ OK ]

Restarting network

root@rhel:~# service network restart

Shutting down interface eth0: [ OK ]

Bringing up interface eth0:

Determining IP information for eth0... done. [ OK ]


Software management (yum & apt)


Slamd64MOPSLinuxZenwalkSUSE LinuxOpenSUSE Knoppix

XandrosLindows/Linspire/FreespireSimplyMEPISUbuntu Family

Red FlagYellow DogCentOSMandrake/MandrivaFedora

Linux distros hierarchy


Some definitions

A software package refers to computer software packaged in an archive format to be installed by a package management system or a self-sufficient installer.

A package management system is a collection of tools to automate the process of installing, upgrading, configuring, and removing software packages from a computer.


Red Hat based

• RPM

• rpm

• yum

Debian based

• DEB

• dpkg

• apt

General Differences between distros


Some definitions

RPM (Red Hat Package Manager) is a package management system. Originally developed by Red Hat for Red Hat Linux, RPM is now used by many Linux distributions.

YUM (The Yellow dog Updater, Modified) is an open source command line package management utility for RPM-compatible Linux operating systems and has been released under the GNU GPL.

deb is the extension of the Debian software package format and the most often used name for such binary packages. Like the "Deb" part of the term Debian, it originates from the name of Debra, then girlfriend and now ex-wife of Debian's founder Ian Murdock

APT, or The Advanced Packaging Tool, is a free user interface that works with core libraries to handle the installation and removal of software on the Debian GNU/Linux distribution and its variants.


YUM: configuration and usage

/etc/yum.conf

yum –hyum list |more yum info firefoxyum search firefoxyum deplist firefoxyum install mcyum remove mcmc check-update

yum update

yum clean all

main configuration file

Viewing yum optionsListing installed packagesGetting package descriptionsSearching for packagesViewing package

dependenciesInstall packageRemove packageCheck for update for

particular packageUpdate all of the outdated

packagesCleaning up the yum cache


YUM: repositories

[root@centos ~]# ls /etc/yum.repos.d/CentOS-Base.repo CentOS-Media.repo

[root@centos ~]# cat /etc/yum.repos.d/CentOS-Base.repo[base]name=CentOS-$releasever – Basebaseurl=http://mirror.yandex.ru/centos/5.4/os/x86_64/gpgcheck=0enabled=1gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5

[updates]name=CentOS-$releasever – Updatesbaseurl=http://mirror.centos.org/centos/$releasever/updates/

$basearch/gpgcheck=1gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5

Name of repo

User friendly name of repo

url to repos

activity flag


apt - Advanced Package Tool

•apt-get•apt-cache•apt-cdrom•aptitude


apt-get

apt-get is a simple command line interface for downloading and installing packages. The most frequently used commands are update and install.

• update - Retrieve new lists of packages• upgrade - Perform an upgrade• install - Install new packages (pkg is libc6 not libc6.deb)

• remove - Remove packages• purge - Remove packages and config files• check - Verify that there are no broken dependencies


apt-cache

apt-cache is a low-level tool used to manipulate APT's binary cache files, and query information from them.

• showpkg - Show some general information for a single package

• search - Search the package list for a regex pattern

• show - Show a readable record for the package• depends - Show raw dependency information for a package

• pkgnames – show all installed packages


apt-cdrom

apt-cdrom is a tool to add CDROM's to APT's source list. The CDROM mount point and device information is taken from apt.conf and etc/fstab.• add - Add a CDROM• ident - Report the identity of a CDROM


aptitude

Synaptic is high-level interface to the package manager

Synaptic Package Manager


aptitude

aptitude is high-level interface to the package manager

aptitude


apt: repositories

root@host-93:~# cat /etc/apt/sources.list

deb ftp://mirror.minsk.epam.com/pub/Ubuntu/ubuntu/ karmic main restricted

deb-src ftp://mirror.minsk.epam.com/pub/Ubuntu/ubuntu/ karmic main restricted

deb ftp://mirror.minsk.epam.com/pub/Ubuntu/ubuntu/ karmic universedeb ftp://mirror.minsk.epam.com/pub/Ubuntu/ubuntu/ karmic-security

maindeb ftp://mirror.minsk.epam.com/pub/Ubuntu/ubuntu/ karmic-security

restricteddeb ftp://mirror.minsk.epam.com/pub/Ubuntu/ubuntu/ karmic-updates

maindeb ftp://mirror.minsk.epam.com/pub/Ubuntu/ubuntu/ karmic-updates

restricted

name of distr

type url to repos types of repos


Samba client


Kickstart

root@ubuntu:~# apt-get install smbclientroot@ubuntu:~# apt-get install smbfs

root@ubuntu:~# smbclient -U name_surname -W minsk.epam.com -L 10.6.5.70

root@ubuntu:~# smbclient -U name_surname -W minsk.epam.com //EPBYMINW0777/upload

root@ubuntu:~# mkdir /media/1/root@ubuntu:~# smbmount

//EPBYMINW0934.minsk.epam.com/upload /media/1/ -o user=name_surname,dom=minsk.epam.com

root@ubuntu:~# ls /media/1/

you must specify existing share!!!


Linux boot process


Boot sequence summary

• BIOS

• LILO or GRUB (boot loader)

• Kernel (+ initrd)

• init

• Run Levels


Boot sequence summary: BIOS

Load boot sector from one of:

• Floppy

• CDROM

• Hard drive

The boot order can be changed from within the BIOS settings.


Boot sequence summary: LILO or GRUB

Lilo (Linux loader)

• does not understand

filesystems

• uses the BIOS routines to load

Loading sequence

• load menu code, typically

/boot/boot.b

• prompt for (or timeout to

default) partition or kernel

• for "image=" option load

kernel image

GRUB (GRand Unified

Bootloader)

• More advanced and

commonly used

• Understands file systems

• config lives in

/boot/grub/menu.lst or

/boot/boot/menu.lst


Boot sequence summary: kernel

• initialize devices

• (optionally loads initrd)

• mounts root filesystem

• runs /sbin/init which is process number 1 (PID=1)


Boot sequence summary: initrd

initrd

• is a temporary file system used by the Linux kernel during

boot

• typically used for making preparations before the real root

file system can be mounted

initramfs – modern substitute for initrd


Boot sequence summary: /sbin/init

reads /etc/inittab (see man inittab)

• Run boot scripts, eg for redhat /etc/rc.d/rc.sysinit which:

• loads modules

• check root FS and mount RW

• mount local FS

• setup network

• mount remote FS

• Switches to default runlevel, eg 3 (defined in /etc/inittab,

eg: id:3:initdefault: )

• run scripts /etc/rc3.d/S*

• run programs specified in /etc/inittab


Boot sequence summary: runlevels

The term runlevel refers to a mode of operation in one of

the computer operating systems that implement Unix

System V-style initialization.

Differs for different UNIX systems and Linux distributives

Red Hat Linux/Fedora runlevels


Managing init levels

root@ubuntu:~# init 3

root@ubuntu:~# telinit 5

root@ubuntu:~# runlevel3 5

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by Aliaksandr Stelmachonak, Dzmitry Kuchko