Chapter 9: Networking with Unix and Linux

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 or Linux server for a corporate network

Objectives: (continued)Explain and execute basic UNIX and Linux commands

Install Linux on an Intel-based PC

Use Linux to add groups and users and to change file access permissions

Explain how UNIX and Linux can be internetworked with other operating systems

A Brief History of UNIX

• AT&T Source code

• System V.

• BSD (Berkeley Software Distribution)

• The SCO Group

• The Open Group

Varieties of UNIX

• UNIX features:• Multiple, simultaneously logged on users

• Multiple, simultaneously running tasks

• Mount disk partitions upon demand

• Permissions for file and directory access

• Uniform method of issuing or receiving data from hardware devices, files, and running programs

Varieties of UNIX (continued)

• UNIX features:• The ability to start a program without interfering

with a currently running program

• Hundreds of subsystems, including dozens of programming languages

• Source code portability

• Window interfaces that the user can configure, the most popular of which is the X Window system

Varieties of UNIX (continued)

• Proprietary UNIX• Licensed copy from The SCO Group

• Popular Vendors

• Sun Microsystems--Solaris

• IBM--AIX

• HP--HP-UX,

Varieties of UNIX (continued)

• Proprietary UNIX• Proprietary UNIX system advantages:

• Accountability and support

• Optimization of hardware and software

• Predictability and compatibility

• One drawback

• No access to the system’s source code

Open Source UNIX

• Open Source UNIX• Open source software or Freely distributable

software

• GNU

• BSD

• Linux

Open Source UNIX (continued)

• Open Source UNIX• Primary advantage

• Cost

• Users can modify its code

• Freely distributable

• Run not only on Intel-based processors, but also on other processor brands

Why Choose Linux?

• What considerations:• Is it compatible with my existing infrastructure?

• Will it provide the security required by my resources?

• Can my technical staff manage it effectively?

• Will my applications run smoothly on it?

• Will it accommodate future growth (is it scalable)?

Why Choose Linux? (continued)

• What considerations: (cont.)• Does it support the additional services required by

my users?

• Does it fit my budget?

• What additional training will it require?

• Can I count on competent and consistent support from its manufacturer?

Linux Server Hardware Requirements

• Table 9-1 shows the minimum hardware requirements for the various components of a Linux server.

• Hardware compatibility list (HCL) at www.tldp.org/HOWTO/Hardware-HOWTO/.

Linux Server Hardware Requirements (continued)

Linux Server Hardware Requirements (continued)

• What additional hardware your server may require:• Which applications and services will run

• How many users

• How much random access memory (RAM)

• How much secondary storage (hard disk)

A Closer Look at Linux

• Linux Multiprocessing• In addition to processes, Linux also supports

threads

• Allocates separate resources (such as memory space) to each process as it is created

• Symmetric multiprocessing (SMP)

A Closer Look at Linux (continued)

• The Linux Memory Model• Use both physical and virtual memory efficiently

• Allocates a memory area for each application

• Attempts to decrease the inefficiency of this practice, however, by sharing memory between programs wherever it can

A Closer Look at Linux (continued)

• The Linux Kernel• Kernel

• Core of the Linux system

• Kernel module

• Instructions for performing a specific task

A Closer Look at Linux (continued)

• Linux File and Directory Structure• Hierarchical file system

• UNIX system was one of the first to implement

• Method of organizing files and directories on a disk in which directories may contain files and other directories

• Most operating systems use hierarchical file systems

A Closer Look at Linux (continued)

A Closer Look at Linux (continued)

• Linux File Services• Native file system type, called ext3

• Allows you to access DOS FAT as well as NTFS

• Can both attach shared file systems and share local partitions with other users

• Windows or NetWare

• Network File System (NFS)

A Closer Look at Linux (continued)

• Linux Internet Services• UNIX-based systems have deep roots in Internet

services

• Leading Internet Web server is an open source software application called Apache

• Original Web tools—including the first browsers and servers—were developed on UNIX-based systems

• Full range of Internet services as standard components

A Linux Command Sampler

• The command line is the primary method of interacting with a Linux system

• Command interpreter

• Shell

A Linux Command Sampler (continued)

• Manual pages (Online documentation)

• Section 1 covers the commands that you most typically enter while typing in a command window.

• Sections 2 through 5 document the programmer’s interface to the Linux system.

• Section 6 documents some of the amusements and games that are included in the Linux system.

A Linux Command Sampler (continued)

• Manual pages (Online documentation)

• Section 7 describes the device drivers for the system.

• Section 8 covers the commands used by administrators to manage the system.

• Section 9 documents the Linux kernel functions programmers use when writing device drivers.

A Linux Command Sampler (continued)

A Linux Command Sampler (continued)

A Linux Command Sampler (continued)

• Command ls (with -l)• Learn everything about a file except its contents:

• The filename

• The file size (in bytes)

• The date and time that the file was created

• The date and time that the file was last accessed (viewed or printed)

A Linux Command Sampler (continued)

• Command ls (with -l) (cont.)• The date and time that the file contents were last

modified

• The number of “aliases” or links to the file

• The numeric identifier of the user who owns the file

• The numeric identifier of the group to which the file belongs

• The access rights for the owner, the group, and all others

A Linux Command Sampler (continued)

A Linux Command Sampler (continued)

• Command ls (with -l) (cont.)• Files with a type of “d” are directories

• “-” are regular files such as word-processing files or spreadsheet files

• “l” for symbolic link files

• “b” for block device files

• “c” for character device files

A Linux Command Sampler (continued)

Configuring Linux for Network Administration

• The basics of adding users and groups

• The basics of modifying file access permissions• Two commands:

• groupadd

• useradd.

Internetworking with Other Network Operating Systems

• Samba• Communicates with Windows servers

• WINE• Enables Windows programs to run on Linux

• VMware• Emulates a complete Intel-based computer

• Telnet

Internetworking with Other Network Operating Systems

(continued)

Internetworking with Other Network Operating Systems

(continued)

Chapter summary

• 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 or Linux server for a corporate network

Chapter summary (continued)

• Explain and execute basic UNIX and Linux commands

• Install Linux on an Intel-based PC

• Use Linux to add groups and users and to change file access permissions

• Explain how UNIX and Linux can be internetworked with other operating systems