1. GNU/Linux Fundamentals Part 3
TO DO:
More slides for permissions (
Network sections should be upended
Software management should be updated and size increased
by Aliaksandr Stelmachonak, Dzmitry Kuchko 1 1

2. Network Configuration2 2

3. ifconfig – configure and control TCP/IP network interfaces
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 3

4. Network interface configurator
display all interfaces which are currently available, even if down
ifconfig –a
ifconfig eth0
ifconfig eth0 up
ifconfig eth0 down
ifconfig eth0 inet netmask
displaying the current state of eth0 interface
Activating and deactivating eth0 interface
Setting configuration for eth0 interface 4

5. $ traceroute google.com $ tracepath ya.ru
Network commands
$ ping google.com
$ ping –c 5 google.com
$ traceroute google.com
$ tracepath ya.ru
$ host ya.ru
$ host
$ dig ya.ru
$ dig –x
sending a ping request
show the network route for a given host
translate ip address to hostname or vice versa
Another method 5

6. Linux distros hierarchy
Slamd64
MOPSLinux
Zenwalk
SUSE Linux
OpenSUSE
Yellow Dog – для PowerPC компьютеров, в частности для Sony Play Station 3!
Red Flag - ведущий дистрибутив в Китае и азиатском регионе.
Red Flag
Yellow Dog
CentOS
Mandrake/Mandriva
Fedora
Knoppix
Xandros
Lindows/Linspire/Freespire
SimplyMEPIS
Ubuntu Family

7. Differences between distros
Debian based
Red Hat based
/etc/sysconfig/network
/etc/sysconfig/network -scripts/ifcfg-ethX
/etc/sysconfig/network
/etc/resolv.conf
/etc/network/interf aces
/etc/hostname
/etc/resolv.conf

8. [root@rhel ~]# cat /etc/sysconfig/network- scripts/ifcfg-eth0
Main Settings
~]# cat /etc/sysconfig/network- scripts/ifcfg-eth0
cat /etc/network/interfa ces
DEVICE=eth0
IPADDR=
NETMASK=
NETWORK=
BROADCAST=
ONBOOT=yes
auto lo eth0
iface eth0 inet static
address
netmask
gateway
dhcp
BOOTPROTO=dhcp

9. [root@rhel ~]# cat /etc/sysconfig/network
Host name
~]# cat /etc/sysconfig/network
cat /etc/hostname
NETWORKING=yes
FORWARD_IPV4=yes
HOSTNAME=myhost.local
GATEWAY=
myhost.local
;-)

10. root@generic-linux:~# cat /etc/resolv.conf
DNS and search domains
cat /etc/resolv.conf
domain minsk.epam.com
search epam.com. minsk.epam.com.
nameserver
nameserver
domain имя - Задает локальное доменное имя в качестве стандарного домена.
search список_поиска - Задает список поиска для имен хостов.
В файле resolv.conf можно указывать до MAXNS (в настоящее время - трех) серверов имен, по одному в строке.

11. root@ubuntu:~# /etc/init.d/networking restart
Restarting network
/etc/init.d/networking restart
* Reconfiguring network interfaces [ OK ]
service network restart
Shutting down interface eth0: [ OK ]
Bringing up interface eth0:
Determining IP information for eth0... done [ OK ]
domain имя - Задает локальное доменное имя в качестве стандарного домена.
search список_поиска - Задает список поиска для имен хостов.
В файле resolv.conf можно указывать до MAXNS (в настоящее время - трех) серверов имен, по одному в строке.

12. Software management (yum & apt)12 12

13. Linux distros hierarchy
Slamd64
MOPSLinux
Zenwalk
SUSE Linux
OpenSUSE
Yellow Dog – для PowerPC компьютеров, в частности для Sony Play Station 3!
Red Flag - ведущий дистрибутив в Китае и азиатском регионе.
Red Flag
Yellow Dog
CentOS
Mandrake/Mandriva
Fedora
Knoppix
Xandros
Lindows/Linspire/Freespire
SimplyMEPIS
Ubuntu Family

14. 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. 14

15. Red Hat based Debian based RPM rpm yum DEB dpkg apt
General Differences between distros
Red Hat based
Debian based
RPM
rpm
yum
DEB
dpkg
apt

16. 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. 16

17. YUM: configuration and usage
/etc/yum.conf
main configuration file
yum –h
Viewing yum options
yum list |more
Listing installed packages
yum info firefox
Getting package descriptions
yum search firefox
Searching for packages
yum deplist firefox
Viewing package dependencies
yum install mc
Install package
yum remove mc
Remove package
mc check-update
Check for update for particular package
yum update
Update all of the outdated packages
yum clean all
Cleaning up the yum cache 17

18. [root@centos ~]# ls /etc/yum.repos.d/
YUM: repositories
~]# ls /etc/yum.repos.d/
CentOS-Base.repo CentOS-Media.repo
~]# cat /etc/yum.repos.d/CentOS-Base.repo
[base]
name=CentOS-$releasever – Base
baseurl=
gpgcheck=0
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-CentOS-5
[updates]
name=CentOS-$releasever – Updates
baseurl=
gpgcheck=1
User friendly name of repo
Name of repo
url to repos
activity flag 18

19. apt - Advanced Package Tool
apt-get
apt-cache
apt-cdrom
aptitude 19

20. 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

21. 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

22. 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

23. Synaptic Package Manager
aptitude
Synaptic is high-level interface to the package manager

24. aptitude
aptitude
aptitude is high-level interface to the package manager

25. 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 universe
deb ftp://mirror.minsk.epam.com/pub/Ubuntu/ubuntu/ karmic-security main
deb ftp://mirror.minsk.epam.com/pub/Ubuntu/ubuntu/ karmic-security restricted
deb ftp://mirror.minsk.epam.com/pub/Ubuntu/ubuntu/ karmic-updates main
deb ftp://mirror.minsk.epam.com/pub/Ubuntu/ubuntu/ karmic-updates restricted
type
url to repos
name of distr
types of repos 25

26. Samba client 26 26

27. root@ubuntu:~# apt-get install smbclient
Kickstart
apt-get install smbclient
apt-get install smbfs
smbclient -U name_surname -W minsk.epam.com -L
smbclient -U name_surname -W minsk.epam.com //EPBYMINW0777/upload
mkdir /media/1/
smbmount //EPBYMINW0934.minsk.epam.com/upload /media/1/ -o user=name_surname,dom=minsk.epam.com
ls /media/1/
you must specify existing share!!! 27

28. Linux boot process 28 28

29. LILO or GRUB (boot loader) Kernel (+ initrd) init Run Levels
Boot sequence summary
BIOS
LILO or GRUB (boot loader)
Kernel (+ initrd)
init
Run Levels
BIOS
Master Boot Record (MBR)
LILO or GRUB
Kernel
init
Run Levels 29

30. 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.
BIOS
Master Boot Record (MBR)
LILO or GRUB
Kernel
init
Run Levels 30

31. GRUB (GRand Unified Bootloader)
Boot sequence summary: LILO or GRUB
Lilo (Linux loader)
GRUB (GRand Unified Bootloader)
does not understand filesystems
More advanced and commonly used
uses the BIOS routines to load
Loading sequence
Understands file systems
load menu code, typically /boot/boot.b
config lives in /boot/grub/menu.lst or /boot/boot/menu.lst
prompt for (or timeout to default) partition or kernel
for "image=" option load kernel image
BIOS
Master Boot Record (MBR)
LILO or GRUB
Kernel
init
Run Levels 31

32. Boot sequence summary: kernel
initialize devices
(optionally loads initrd)
mounts root filesystem
runs /sbin/init which is process number 1 (PID=1)
BIOS
Master Boot Record (MBR)
LILO or GRUB
Kernel
init
Run Levels 32

33. Boot sequence summary: 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
The complete linux driver set, covering every interface and file system that might be required, runs to many megabytes of object code. It is undesirable to waste memory on drivers for hardware that the system doesn't have, and so many drivers are provided as kernel modules, that are loaded only when they're needed, instead of monolithically compiled into the kernel itself. This saves memory, as it is not possible to unload drivers that are "monolithically" compiled into the kernel.
A system can only boot if it has drivers for the boot hardware. In principle this could include any extant network or storage device, yet if every driver were pre-loaded "just in case" it was needed, the kernel would become infeasibly large.
This problem is solved by storing the modules in a ramdisk, which is loaded into memory along side the kernel during the operating system boot process. As all the modules are available in memory, they can then be copied into the kernel without resorting to other drivers. Once the kernel has loaded all the drivers it needs for the available hardware, the ramdisk can be released, and the "real" root file system mounted. Hence initrd, the INITial RamDisk was created. 33

34. 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
BIOS
Master Boot Record (MBR)
LILO or GRUB
Kernel
init
Run Levels 34

35. Red Hat Linux/Fedora runlevels
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
The term runlevel refers to a mode of operation in one of the computer operating systems that implement Unix System V-style initialization. Conventionally, seven runlevels exist, numbered from zero to six; though up to ten, from zero to nine, may be used. S is sometimes used as a synonym for one of the levels.
In standard practice, when a computer enters runlevel zero, it halts, and when it enters runlevel six, it reboots. The intermediate runlevels (1-5) differ in terms of which drives are mounted, and which network services are started. Lower run levels are useful for maintenance or emergency repairs, since they usually don't offer any network services at all. The particular details of runlevel configuration differ widely among operating systems, and slightly among system administrators.
The runlevel system replaced the traditional /etc/rc script used in Version 7 Unix. 35

36. root@ubuntu:~# telinit 5 root@ubuntu:~# runlevel 3 5
Managing init levels
init 3
telinit 5
runlevel
3 5
current
previous
The term runlevel refers to a mode of operation in one of the computer operating systems that implement Unix System V-style initialization. Conventionally, seven runlevels exist, numbered from zero to six; though up to ten, from zero to nine, may be used. S is sometimes used as a synonym for one of the levels.
In standard practice, when a computer enters runlevel zero, it halts, and when it enters runlevel six, it reboots. The intermediate runlevels (1-5) differ in terms of which drives are mounted, and which network services are started. Lower run levels are useful for maintenance or emergency repairs, since they usually don't offer any network services at all. The particular details of runlevel configuration differ widely among operating systems, and slightly among system administrators.
The runlevel system replaced the traditional /etc/rc script used in Version 7 Unix. 36

37. Questions? 