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  1. 1. Linux Networking <ul><li>Here, you’ll learn about: </li></ul><ul><li>Linux Basics </li></ul><ul><li>Installing Linux </li></ul><ul><li>The installation and configuration of Linux network services </li></ul>
  2. 2. Linux Basics
  3. 3. History of Linux <ul><li>Operating system initially created as a hobby by a young student, Linus Torvalds, at the University of Helsinki in Finland </li></ul><ul><li>Linus had an interest in Minix, a small UNIX system, and decided to develop a system that exceeded the Minix standards </li></ul><ul><li>He began his work in 1991 when he released version 0.02 and worked steadily until 1994 when version 1.0 of the Linux Kernel was released </li></ul>
  4. 4. What is Linux? <ul><li>A Unix clone written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the net </li></ul><ul><li>Not Unix due to the fact that its code was not derived in anyway from the original Unix </li></ul><ul><li>POSIX (Portable Operating System Interface) compliant </li></ul>
  5. 5. What is Linux? <ul><li>Has all the features you would expect in a modern full-fledged Unix, </li></ul><ul><ul><li>true multitasking </li></ul></ul><ul><ul><li>virtual memory </li></ul></ul><ul><ul><li>shared libraries </li></ul></ul><ul><ul><li>tandem and loading </li></ul></ul><ul><ul><li>shared copy-on-write executables </li></ul></ul><ul><ul><li>proper memory management </li></ul></ul><ul><ul><li>TCP/IP networking. </li></ul></ul>
  6. 6. What is Linux? <ul><li>Runs mainly on 386/486/586-based PCs, using the hardware facilities of the 386 processor family (TSS segments et al) to implement these feature </li></ul><ul><li>Ports to other architectures are also in development </li></ul><ul><li>It is extremely stable, as people who encounter bugs in Linux while writing their own programs can actually fix the Linux bugs and submit the fixes to distribution maintainers </li></ul>
  7. 7. How much does Linux Cost? <ul><li>Nothing. Yes, Linux cost absolutely nothing because it is under the GNU General Public License, which basically means that you may freely copy, change and distribute it, but that you may not impose any restrictions on further distribution, and that you must make the source code available. </li></ul>
  8. 8. Standards <ul><li>UNIX </li></ul><ul><ul><li>a trademark (owned by the Open Group) </li></ul></ul><ul><ul><li>systems must pass certification to use name </li></ul></ul><ul><li>Linux is not a funded operation. </li></ul><ul><ul><li>believed to conform to necessary standards </li></ul></ul><ul><ul><li>could pass certification such as POSIX </li></ul></ul><ul><ul><li>under the GNU GPL license </li></ul></ul>
  9. 9. Systems that Support Linux <ul><li>Intel 80x86 architecture </li></ul><ul><li>Motorola 68k - amigas, apples and ataris </li></ul><ul><li>Power pc - macintosh and apple PCs </li></ul><ul><li>The 64-bit DEC Alpha/AXP </li></ul><ul><li>MIPS - R4600 </li></ul><ul><li>ARM processors - A5000 and Acom RISC PC </li></ul><ul><li>Sparc - Sun Servers and Workstations </li></ul><ul><li>and many more </li></ul>
  10. 10. Linux Hardware Requirements <ul><li>Can run on much more modest hardware than most other modern operating systems require </li></ul><ul><li>An old 486 with 16 megabytes of ram and 500 megs of hard drive space has plenty of capacity to host an intranet, including duties as firewall and print/SMTP/POP server for dozens of other computers </li></ul><ul><li>Will boot and run (with full graphical user interface) in less than 4 megabytes of ram, and 8 megs of ram is plenty for web-surfing with Netscape. </li></ul>
  11. 11. Linux Distributions <ul><li>Contains the software you need to run Linux, ready to install and use </li></ul><ul><li>Installation HOWTO contains details on how to go about installing Slackware, Red Hat and Debian. Mandrake, SuSE, TurboLinux are more recent, and have more sophisticated installation schemes, but they are less widely used and don't contain quite as wide a range of software </li></ul><ul><li>All of those releases are available via anonymous FTP from various Linux archive sites. </li></ul>
  12. 12. Why Use Linux? <ul><li>Cheap, fast, flexible, efficient, stable, secure, reliable, legal, easy to install, requires low maintenance, thoroughly tested, and currently running somewhere around half the internet </li></ul><ul><li>Supports a wide range of hardware </li></ul><ul><li>There are dozens of public companies, educational institutions, government organizations, and individuals contributing device drivers to Linux </li></ul><ul><li>Almost all Linux distributions are available in their entirety as free downloads via FTP or CD-ROMs </li></ul>
  13. 13. Linux Features <ul><li>Component-based systems </li></ul><ul><li>Very popular with technically skilled </li></ul><ul><li>Not ‘solution’ oriented </li></ul><ul><li>Highly network-aware </li></ul><ul><li>Robust, powerful, reliable </li></ul>
  14. 14. Kernel of a System <ul><li>What is called Linux is actually a collection of components from many sources </li></ul><ul><li>Can be freely copied, under `open source' licenses </li></ul><ul><li>Linux is, strictly, just the kernel which provides: </li></ul><ul><ul><li>a common interface between user process and hardware </li></ul></ul><ul><ul><li>minimal functions to user applications, i.e. system calls </li></ul></ul>
  15. 15. Many Faces of a GNU/Linux System <ul><li>The user may see up to five aspects of Linux: </li></ul><ul><ul><li>the filesystem </li></ul></ul><ul><ul><li>processes </li></ul></ul><ul><ul><li>the shell </li></ul></ul><ul><ul><li>the X windowing system </li></ul></ul><ul><ul><li>Inter-Process Communication (IPC) </li></ul></ul><ul><li>The system is very highly configurable </li></ul>
  16. 16. Many Faces of a GNU/Linux System <ul><li>Different users may experience totally different views of the same system </li></ul><ul><li>Multiple simultaneous users are normal </li></ul><ul><li>Linux is designed from the ground up as a multi-user system , NOT a ‘personal’ system </li></ul>
  17. 17. Installing Linux
  18. 18. Choosing Your Distribution <ul><li>Obtain the distribution from one of the sources mentioned in the previous slides </li></ul><ul><li>If you want more control you can choose slackware </li></ul><ul><li>If you want ease of installation you can choose redhat or mandrake </li></ul><ul><li>Read the step by step instructions found on each distribution package </li></ul>
  19. 19. Readying your Hardware <ul><li>Determine your processor type and speed </li></ul><ul><li>Check out your available RAM </li></ul><ul><li>Determine your hard disk types and sizes </li></ul><ul><li>List down other drives in your system such as CDROM drives and floppy disk drives </li></ul><ul><li>List down all other expansion cards in your system such as sound cards, NICs, and etc. </li></ul><ul><li>Get a list of all the peripherals you have such as mouse, keyboard, monitor type </li></ul>
  20. 20. List what services you need <ul><li>Determine what services you would like to implement in your server? </li></ul><ul><li>Take into consideration what you would like your system to do such as email, ftp, web servers </li></ul><ul><li>In the other hand you can also check whether you would like a word processor, spreadsheet, browser </li></ul><ul><li>Never neglect the network and system management tools </li></ul>
  21. 21. List what services you need <ul><li>Also consider other services you might not need </li></ul><ul><ul><li>dependencies - if you want to compile a kernel in the future you must include the gnu c tools , the c development libraries and the kernel headers in order to compile one </li></ul></ul><ul><ul><li>future needs - something you might not need now but you might need later such as a database server </li></ul></ul>
  22. 22. Quick Installation Procedure <ul><li>Make your linux bootdisk. </li></ul><ul><ul><li>use the rawrite program contained in your linux distribution </li></ul></ul><ul><li>Partition your hard disk. </li></ul><ul><ul><li>make a main partition with at least 300MB </li></ul></ul><ul><ul><li>the next will be the swap partition that must be twice the amount of physical RAM you have </li></ul></ul><ul><li>Boot your linux boot disk </li></ul><ul><li>Follow the instructions of the installation program. </li></ul>
  23. 23. Installing Network Services to an Existing Linux System
  24. 24. Install <ul><li>Install the network card device drivers. </li></ul><ul><li>Run the command: netconf </li></ul><ul><li>Select Basic Host Configuration </li></ul><ul><li>The most important area in the configuration is the linux module. All network cards are supported through modules. The modules are found in the /lib/modules directory. </li></ul>
  25. 25. Install <ul><li>E.g. The 3com 3c509 card will have a module name 3c509.o However, the name entered in the netconf screen should only be 3c509 (no .o) </li></ul><ul><li>Each network card is denoted by ethx where x is the number of the network card. Linux counts starting from 0. For the first ethernet card, we have eth0. For the 2 nd ethernet card, we have eth1. And so on. </li></ul>
  26. 26. Inetd <ul><li>The Internet Service Super Daemon. </li></ul><ul><li>A daemon is a server in Linux. </li></ul><ul><li>Inetd server handles the activation of the following services: </li></ul><ul><ul><li>telnet </li></ul></ul><ul><ul><li>ftp </li></ul></ul><ul><ul><li>Pop </li></ul></ul><ul><ul><li>Imap </li></ul></ul><ul><ul><li>Linuxconf (web based) </li></ul></ul><ul><ul><li>Swat (SMB web interface) </li></ul></ul>
  27. 27. Notes <ul><li>All configuration files in linux is placed in the /etc directory. All the lines in the file are related to the configuration except for the lines that start with a # sign. The # sign signals a comment, the descriptions in the files. </li></ul><ul><li>Network services can be started, stopped, and restarted by accessing the right program in the /etc/rc.d/init.d directory. E.g. To restart inetd server, we type, /etc/rc.d/init.d/inetd restart No need to restart the whole machine. </li></ul>
  28. 28. Xinetd <ul><li>RedHat 7.x released a variation of inetd that instead of looks only at a file, it looks for a series of configuration files. They called the server xinetd. </li></ul><ul><li>The xinetd server is configured through the following files: </li></ul><ul><ul><li>/etc/xinetd.conf file </li></ul></ul><ul><ul><li>/etc/xinetd.d directory </li></ul></ul>
  29. 29. Xinetd <ul><li>Inside the /etc/xinetd.d directory, each file represents a network service that is either activated or deactivated by setting the disable=yes or disable=no value. </li></ul><ul><li>Exercise: Activate the Linuxconf web based access in xinetd. </li></ul>
  30. 30. Linuxconf <ul><li>Linuxconf is an integrated systems and network configuration tool for RedHat linux </li></ul><ul><li>It can be activated in three ways: </li></ul><ul><li>Command based (through the command line) </li></ul><ul><li>GUI based (through the X-windows screen) </li></ul><ul><li>Web based (through the browser) </li></ul>
  31. 31. Activate Linuxconf <ul><li>Open Config => Networking => Misc => Linuxconf network access </li></ul><ul><li>Enter the hostnames you want to give access to linuxconf </li></ul><ul><li>Click on the accept button </li></ul><ul><li>Also, verify that the disable line in the /etc/xinetd.d/linuxconf-web file reads disable=no </li></ul><ul><li>Reload the xinetd server </li></ul>
  32. 32. Activate Linuxconf <ul><li>To access Linuxconf via the browser: </li></ul><ul><li>Type in the URL http://servername:98 where the servername is the machine name or ip address of the computer you want to manage. </li></ul>
  33. 33. Samba <ul><li>Samba uses the SMB protocol to share files and printers across a network connection. Operating systems that support this protocol include Microsoft Windows (through its Network Neighborhood), OS/2, and Linux. </li></ul><ul><li>Samba is useful if you have a network of both Windows and Linux machines. Samba will allow files and printers to be shared by all the systems in your network. </li></ul>
  34. 34. Samba Configuration <ul><li>Samba uses /etc/samba/smb.conf as its configuration file </li></ul><ul><li>Changes will not take effect until you restart the Samba daemon with the command service smb restart. </li></ul>
  35. 35. Default Samba Configuration <ul><li>Allows users to view their Linux home directories as a Samba share on the Windows machine after they log in using the same username and password </li></ul><ul><li>Also shares any printers configured for the Red Hat Linux system as Samba shared printers. In other words, you can attach a printer to your Red Hat Linux system and print to it from the Windows machines on your network </li></ul>
  36. 36. Samba Configuration <ul><li>To specify the Windows workgroup and description string, edit the following lines in your smb.conf file: </li></ul><ul><ul><li>workgroup = WORKGROUPNAME </li></ul></ul><ul><ul><li>server string = BRIEF COMMENT ABOUT SERVER </li></ul></ul>
  37. 37. Creating a Samba Share <ul><li>Add the following section to your smb.conf file </li></ul><ul><ul><li>[sharename] </li></ul></ul><ul><ul><li>comment = Insert a comment here </li></ul></ul><ul><ul><li>path = /home/share/ </li></ul></ul><ul><ul><li>valid users = tfox carole </li></ul></ul><ul><ul><li>public = no </li></ul></ul><ul><ul><li>writable = yes </li></ul></ul><ul><ul><li>printable = no </li></ul></ul><ul><ul><li>create mask = 0765 </li></ul></ul>
  38. 38. Samba <ul><li>To connect to a Linux Samba share from a Microsoft Windows machine, use Network Neighborhood or Windows Explorer. </li></ul><ul><li>Or from the command prompt, type: </li></ul><ul><ul><li>ervernamesharename </li></ul></ul><ul><li>To connect to a Samba share from a Linux system, from a shell prompt, type the following command: smbclient //hostname/sharename -U username </li></ul>
  39. 39. SWAT <ul><li>Samba Web Administration Tool is the default GUI manager that comes with Samba </li></ul><ul><li>You can activate the SWAT service by adding a line in the /etc/services file: swat 901/tcp </li></ul><ul><li>And configuring the swat file in the /etc/xinetd.d directory to disable=no. </li></ul>
  40. 40. SWAT <ul><li>To access the SWAT service through the browser: </li></ul><ul><li>http://servername:901 where servername is the machine or computer name of the computer you want to configure. </li></ul>
  41. 41. Apache <ul><li>The most popular webserver is the apache webserver. </li></ul><ul><li>You can download the latest version from </li></ul><ul><li>Apache is configured manually through the directory /etc/httpd </li></ul><ul><li>Most of the configuration is applied on the file /etc/httpd/conf/httpd.conf </li></ul><ul><li>Apache can also be configured through the GUI via the command apacheconf </li></ul>
  42. 42. Reference Websites for Linux <ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul>