1. Chapter Ten Networking with UNIX

2. Objectives Describe the origins and history of the UNIX operating system Identify similarities and differences between popular implementations of UNIX Understand why you might choose a UNIX server for a corporate network

3. Objectives Explain and execute basic UNIX commands Install Linux on an Intel-based PC Use Linux to add groups and users and to change file access permissions Explain how UNIX can be internetworked with other network operating systems

4. Brief History of UNIX System V Versions of UNIX that come from Bell Labs Versions of UNIX that come from Bell Labs BSD (Berkeley Software Division) Versions of UNIX from researchers at the University of California at Berkeley Versions of UNIX from researchers at the University of California at Berkeley Caldera International and Tarantella jointly own the rights to the UNIX source code

5. Common UNIX Features The ability to support multiple, simultaneously logged in users Hierarchical file systems that incorporate demountable volumes Consistent interfaces for input of data to and output of data from hardware devices, files, and running programs The ability to start processes in the background

6. Common UNIX Features Hundreds of subsystems, including dozens of programming languages Program source code portability Windows interfaces that the user can configure, the most popular of which is the X Window system

7. Current State of the Market Unix market is huge and highly segmented Some real-time implementations of the UNIX system exist In a real-time implementation, the operating system must respond to input immediately In a real-time implementation, the operating system must respond to input immediately

8. Proprietary UNIX An implementation of UNIX for which the source code is either unavailable or available only by purchasing a licensed copy from Caldera International and Tarantella Sun’s proprietary version of UNIX is called Solaris Sun’s proprietary version of UNIX is called Solaris IBM’s proprietary version of UNIX is called AIX IBM’s proprietary version of UNIX is called AIX HP’s proprietary version of UNIX is called HP- UX HP’s proprietary version of UNIX is called HP- UX

9. Choosing a Proprietary UNIX System Advantages Accountability and support Accountability and support Optimization of hardware and software Optimization of hardware and software Predictability and compatibility Predictability and compatibilityDrawback Customer has no access to the system’s source code and thus cannot create a custom solution Customer has no access to the system’s source code and thus cannot create a custom solution

10. Open Source UNIX Open source software Software developed and packaged by a few individuals and made available to anyone without licensing fees Software developed and packaged by a few individuals and made available to anyone without licensing fees Also called freely distributed software Also called freely distributed software UNIX-like systems in this category include GNU, FreeBSD, and Linux Different implementations of UNIX-like systems are known as flavors Freely distributable versions of UNIX include a copyright called the General Public License Freely distributable versions of UNIX include a copyright called the General Public License

11. Why Choose UNIX? Is it compatible with existing infrastructure? Will it provide the security required by the network’s resources? Can the technical staff manage it effectively? Will existing applications run smoothly on it?

12. Why Choose UNIX? Will it accommodate future growth (that is, is it scalable)? Does it support additional services the network’s users require? How much does it cost? What type of sort can be expected from the vendor?

13. Choosing UNIX Samba Open source software package Open source software package Complete Windows 2000-style file and print sharing facility Complete Windows 2000-style file and print sharing facility UNIX was originally developed as a time- sharing system Computing system to which each user must attach directly to share the resources of that computer Computing system to which each user must attach directly to share the resources of that computer Some proprietary UNIX systems have received Orange Book certification

14. UNIX Server Hardware Base system unit must include: Motherboard with CPU, memory, and I/O control Motherboard with CPU, memory, and I/O control Network interface card (NIC) Network interface card (NIC) Floppy disk drive Floppy disk drive CD-ROM drive CD-ROM drive One or more fixed disks One or more fixed disks

15. Decisions in Choosing Hardware Which applications and services will run on the server? How many users will this system serve? How much random access memory (RAM) will the server need? How much secondary storage (hard disk) will the server need?

16. Decisions in Choosing Hardware Table 10-1: Typical hardware requirements for a Linux server

17. A Closer Look at Linux Linux multiprocessing Supports symmetric multiprocessing (SMP) Supports symmetric multiprocessing (SMP) Linux memory model From its inception, Linux was created to use both physical and virtual memory efficiently From its inception, Linux was created to use both physical and virtual memory efficiently

18. Linux Kernel Kernel As in NetWare, is the core of the system As in NetWare, is the core of the system Also similar to NetWare, it is possible to add or remove functionality by loading and unloading Linux kernel modules Also similar to NetWare, it is possible to add or remove functionality by loading and unloading Linux kernel modules Analogous to NetWare NLMs

19. Linux File and Directory Structure Hierarchical file system Organization of files and directories on a disk partition in which directories may contain files and directories Organization of files and directories on a disk partition in which directories may contain files and directories FIGURE 10-1 Linux file system hierarchy

20. Linux File Services Linux includes support for multiple types of file systems, including: Local file systems Local file systems Remote file systems Remote file systems Its native file system, called ext2 Its native file system, called ext2 Sun Microsystem’s Network File System (NFS) Sun Microsystem’s Network File System (NFS)

21. Linux Internet Services and Linux Processes Linux Internet Services Apache Apache Open source software application that is the leading Internet Web server Linux Processes Another UNIX innovation is the notion of separate, numbered processes Another UNIX innovation is the notion of separate, numbered processes

22. Linux Command Sampler Command interpreter Program that accepts your typing and runs the command Program that accepts your typing and runs the command Also known as a shell Also known as a shell Keeps track of the command history, much like the doskey command in DOS and Windows 2000 Keeps track of the command history, much like the doskey command in DOS and Windows 2000

23. Linux Command Sampler Manual pages Section 1 covers commands typically entered while typing in a command window Section 1 covers commands typically entered while typing in a command window Sections 2 through 5 document the programmer’s interface to the UNIX system Sections 2 through 5 document the programmer’s interface to the UNIX system Section 6 documents some of the amusements and games that are included in the UNIX system Section 6 documents some of the amusements and games that are included in the UNIX system

24. Linux Command Sampler Manual pages Section 7 describes the device drivers for the system Section 7 describes the device drivers for the system Section 8 covers the commands used by administrators to manage the system Section 8 covers the commands used by administrators to manage the system Section 9 documents the UNIX kernel functions programmers use when writing device drivers Section 9 documents the UNIX kernel functions programmers use when writing device drivers

25. Linux Command Sampler Globbing Form of filename substitution Form of filename substitutionPipe Serves as the connection between two commands Serves as the connection between two commandsPipeline Two or more commands separated by a pipe Two or more commands separated by a pipe

26. Linux Command Sampler TABLE 10-2a: Commonly used Linux commands

27. Linux Command Sampler TABLE 10-2b: Commonly used Linux commands (cont.)

28. Linux Command Sampler Linux systems keep quite a bit of information about each file, including: Filename Filename File size (in bytes) File size (in bytes) Date and time a file’s i-node (file information node) was created Date and time a file’s i-node (file information node) was created Date and time that the file was last accessed Date and time that the file was last accessed Date and time that the file contents were last modified Date and time that the file contents were last modified

29. Linux Command Sampler Information Linux system keeps about each file (cont.): Number of “aliases” or links to the file Number of “aliases” or links to the file Numeric identifier of the user who owns the file Numeric identifier of the user who owns the file Numeric identifier of the group to which the file belongs Numeric identifier of the group to which the file belongs Access rights for the owner, the group, and all others Access rights for the owner, the group, and all others

30. Linux Command Sampler To learn about the i-node information, use the ls command Figure 10-2: Example of output from ls

31. Linux Command Sampler Valid file types “d” for directories “d” for directories “l” for symbolic link files “l” for symbolic link files “b” for block devices “b” for block devices “c” for character device files “c” for character device files

32. Linux Command Sampler FIGURE 10-3 Anatomy of ls output

33. Linux Preinstallation Questions What is the new server’s name? What is the server’s IP address? What kind of video card is installed in the server? What kind of monitor is attached to the new server? What is the administrative user’s password? How can I remember all this information?

34. Linux Preinstallation Questions Linux very peacefully coexists with other operating systems on your primary hard drive Read more about multiboot systems at the Linux installation HOWTO site: http://www.linuxhq.com/ldp/howto/Installation- HOWTO/index.html http://www.linuxhq.com/ldp/howto/Installation- HOWTO/index.html

35. The Installation Process Figure 10-4: Welcome to Red Hat Linux screen

36. The Installation Process Figure 10-5: Network Configuration screen

37. Configuring Linux for Network Administration Adding groups and users Groupadd Groupadd Command to add a new group ID to a Linux system Useradd Useradd Command to add a new user ID to a Linux system

38. Changing File Access Permissions Linux restricts access to resources by comparing user and group IDs with the owner and membership of files Every file and directory on a Linux system is owned by exactly one user and is a member of exactly one group You may assign access permissions for the file’s owner, the file’s group, and everyone else

39. Internetworking with Other Network Operating Systems SambaIPX/SPXAppleTalkX3270WINEVMWare Dozens and dozens of command-line utilities that enable access to contents of files generated on other systems

40. Chapter Summary The UNIX system is stable, robust network operating system The key difference between freely distributable UNIX and proprietary implementations is that the copyright on freely distributable implementations require that anyone purchasing an open source version of UNIX receive access code to the source UNIX systems make great Internet servers One characteristic of all UNIX systems is a user- definable command interpreter

41. Chapter Summary The UNIX system was among the first operating systems to include a hierarchical file system Each UNIX process represents an instance of a running executable program in core memory UNIX commands can be likened to ordinary sentences Most UNIX commands are lowercase alphabetic characters

42. Chapter Summary Command names are usually acronyms or abbreviations The system uses information nodes (i- nodes) to store everything other than the actual contents of files Linux distributions are binary compatible UNIX systems quite competently interoperate with other network operating systems