# Learning DebianGNU Linux-Chapter 10. Setting Up a Linux-Based LAN

Chia sẻ: Thanh Cong | Ngày: | Loại File: PDF | Số trang:44

0
48
lượt xem
5

## Learning DebianGNU Linux-Chapter 10. Setting Up a Linux-Based LAN

Mô tả tài liệu

Tham khảo tài liệu 'learning debiangnu linux-chapter 10. setting up a linux-based lan', công nghệ thông tin, hệ điều hành phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả

Chủ đề:

Bình luận(0)

Lưu

## Nội dung Text: Learning DebianGNU Linux-Chapter 10. Setting Up a Linux-Based LAN

1. 10. Setting Up a Linux-Based LAN This chapter explains how to set up a local-area network (LAN) that includes a Linux Samba server, which lets Microsoft Windows and UNIX systems access shared files and printers hosted by your Linux system. The chapter explains how to administer a simple LAN and describes how to install, configure, and administer Samba servers and clients. Integrating your Linux system with an existing LAN is no more complicated than setting up your own LAN; the chapter also explains how to connect to an existing network. The chapter also explains how to use Linux backup and recovery utilities so that client systems can create and use backups stored on the server. 10.1 Introduction One of the great strengths of Linux is its powerful and robust networking capabilities. The good news is that everything about Linux's networking setup is open to inspection and completely configurable. Nothing is hidden from the user, and no parameters are forced on you. The challenge is to get the most out of this setup for your needs. Basic networking principles don't differ much between Windows and Linux, and indeed the principles aren't unfamiliar. This chapter starts with an overview of networking, and then looks in more detail at Linux networking on a Local Area Network (LAN). In the next two chapters, you'll learn about making a dialup Internet connection, and setting up Wide Area Network (WAN) services.
2. Most computers today handle network traffic much as the post office handles mail. Think, for example, of the steps involved in sending and receiving a letter. Your postal carrier must know where to drop off and where to pick up mail. So your home must have some kind of recognizable interface; we call this a mailbox. And whereas your postal carrier may know your neighborhood quite well, delivery in other areas will require other carriers. Mail is passed to these other carriers through a gateway; we call this the Post Office. Although you can think of the whole postal system as one big network, it's easier to understand if you think of it as a hierarchy of subnetworks (or subnets): the postal system is divided into states, states are divided by zip code, zip codes contain a number of streets, and each street contains unique addresses. Computer networking mirrors this model. Let's trace an email message from you to a coworker. You compose the message and press Send. Your computer passes the message to a network interface. This interface may be a modem by which you dial up an ISP, or it may be an Ethernet card that connects you to a LAN. Either way, on the other side of the interface is a gateway machine. The gateway knows how to look at the address of the recipient on the email message, and interpret that message in terms of networks and subnets. Using this information, your gateway passes the message to other gateways until the message reaches the gateway for the destination machine. That gateway in turn delivers the message via a recognizable interface (such as modem or Ethernet card) to the recipient's inbox.
7. ifconfig eth0 ${IPADDR} netmask${NETMASK} broadcast ${BROADCAST} route add default qw${GATEWAY} metric 1 The lines you're concerned with are the lines four through eight, each of which has the following form: variable= ipnumber The lines associate a name, given by variable, with a network address, given by ipnumber. The variables are referenced by the following three lines, which are commands that configure networking. To change your network configuration, you need merely to associate the proper IP number with each variable. You can do so by logging in as root and modifying the /etc/init.d/network file by using a text editor. Table 10.1 describes each variable. Your network administrator should be able to provide you with the proper values. Table 10.1: Network Configuration Variables
9.  Query a DNS server (you configured your system's DNS client earlier)  Read the contents of the file /etc/hosts, known as the hosts file, which you'll learn about in the next subsection  Query an NIS (Network Information System) server However, unless your system is part of a sophisticated local area network, it's unlikely that an NIS server is available. Therefore, most systems can query a DNS server and, failing to obtain an answer, read the /etc/hosts file. Alternatively, most systems can read the etc/hosts file and, failing to obtain an answer, query a DNS server. The second alternative is generally better, because reading the /etc/hosts file takes less time than querying a DNS server. The /etc/host.conf/ file specifies which of these three operations are performed, and the order in which they're attempted. You can edit this file by logging in as root. Here's a typical file: order hosts,bind multi on The order line specifies that the system should first consult the /etc/hosts file and then query a DNS server, referred to as bind because of the Berkeley Internet Name Daemon, an early DNS server.
10. The multi line specifies that your system will attempt to locate all possible names for a host when it reads the /etc/hosts file. Unless that file is very large (hundreds or thousands of lines), you should include the multi line. 10.2.6 Miscellaneous Network Configuration Options The hosts file, /etc/hosts, lets your system determine the network address number that corresponds to a hostname, without querying a DNS server. Besides being faster than querying a DNS server, the /etc/hosts file is always available. Entries in the file have two parts:  an IP address  a hostname, or a list of hostnames separated by spaces By default, the hosts file contains an entry that associates the hostname localhost with the IP address 127.0.0.1. It's not necessary that you include any other entries in the /etc/hosts file. However, most system administrators include at least a second line, which associates the local hostname with its network address. Here's a typical file: 127.0.0.1 localhost 192.168.1.10 debian.mccarty.org debian Notice that the second line gives both the fully qualified hostname, consisting of the hostname and domain name, as well as the hostname alone.
11. The /etc/networks file, known as the networks file, performs a function similar to that of the hosts file; whereas the hosts file associates hostnames with network addresses, the networks file associates networks' names with network addresses. By default, the networks file contains a single line associating the network address of the local area network with the name localnet: localnet 192.168.1.0 Generally, it's not necessary that you add other entries to the networks file. However, by doing so, you can access frequently used networks by name even if your DNS server is unavailable. 10.3 Samba Available since version 3.11 of Microsoft Windows, printer and file sharing are two of Window's most useful features. For example, outfitting each computer in a large office with a laser printer would be quite expensive. But printer sharing lets you reduce the cost of providing every user with printing capability; with printer sharing, each computer system in the office can print to a single printer. Just as printer sharing lets your computer access a printer attached to another computer, file sharing lets your computer access files stored on another computer. File sharing makes it quick and easy to transfer data from one system to another and avoids the confusion that results when everyone has their own - possibly out of date or inconsistent - copy of important data files they could not otherwise access.
12. To provide printer and file sharing, Microsoft Windows uses a facility known as SMB (Server Message Block). This same facility is sometimes known as NetBIOS or LanManager. Thanks to Andrew Tridgell and others, Linux systems provide support for SMB via a package known as Samba. Like SMB, Samba lets you:  Share printers and files among Microsoft Windows, OS/2, Netware, and Unix systems  Establish a simple nameserver for identifying systems on your local area network  Backup PC files to a Linux system and restore them  Administer users and passwords Samba has proven its reliability and high performance in many organizations. According to the online survey at http://www.samba.org/pub/samba/survey/ssstats.html, Bank of America is using Samba in a configuration that includes about 15,000 clients, and Hewlett-Packard is using Samba in a configuration that includes about 7,000 clients. 10.3.1 Samba Server Installation If you've never installed and configured a network server, Samba's a good place to begin; its installation and configuration are generally simple and straightforward.