1 | <?xml version="1.0" encoding="ISO-8859-1"?> |
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2 | <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
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3 | "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [ |
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4 | <!ENTITY % general-entities SYSTEM "../../general.ent"> |
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5 | %general-entities; |
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6 | ]> |
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7 | |
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8 | <sect1 id="ch-network-hosts"> |
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9 | <?dbhtml filename="hosts.html"?> |
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10 | |
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11 | <title>Customizing the /etc/hosts File</title> |
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12 | |
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13 | <indexterm zone="ch-network-hosts"> |
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14 | <primary sortas="e-/etc/hosts">/etc/hosts</primary> |
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15 | </indexterm> |
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16 | |
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17 | <indexterm zone="ch-network-hosts"> |
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18 | <primary sortas="d-localnet">localnet</primary> |
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19 | <secondary>/etc/hosts</secondary></indexterm> |
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20 | |
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21 | <indexterm zone="ch-network-hosts"> |
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22 | <primary sortas="d-network">network</primary> |
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23 | <secondary>/etc/hosts</secondary></indexterm> |
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24 | |
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25 | <para>If a network card is to be configured, decide on the IP address, |
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26 | fully-qualified domain name (FQDN), and possible aliases for use in the |
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27 | <filename>/etc/hosts</filename> file. The syntax is:</para> |
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28 | |
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29 | <screen><IP address> myhost.example.org aliases</screen> |
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30 | |
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31 | <para>Unless the computer is to be visible to the Internet (i.e., |
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32 | there is a registered domain and a valid block of assigned IP |
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33 | addresses—most users do not have this), make sure that the IP |
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34 | address is in the private network IP address range. Valid ranges |
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35 | are:</para> |
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36 | |
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37 | <screen><literal>Private Network Address Range Normal Prefix |
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38 | 10.0.0.1 - 10.255.255.254 8 |
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39 | 172.x.0.1 - 172.x.255.254 16 |
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40 | 192.168.y.1 - 192.168.y.254 24</literal></screen> |
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41 | |
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42 | <para>x can be any number in the range 16-31. y can be any number in the |
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43 | range 0-255.</para> |
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44 | |
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45 | <para>A valid IP address could be 192.168.1.1. A valid FQDN for this |
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46 | IP could be <uri>www.clfs.org</uri> (not recommended |
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47 | because this is a valid registered domain address and could cause |
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48 | domain name server issues).</para> |
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49 | |
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50 | <para>Even if not using a network card, a valid FQDN is still required. |
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51 | This is necessary for certain programs to operate correctly.</para> |
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52 | |
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53 | <para>Create the <filename>/etc/hosts</filename> file by running:</para> |
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54 | |
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55 | <screen role="nodump"><userinput>cat > /etc/hosts << "EOF" |
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56 | <literal># Begin /etc/hosts (network card version) |
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57 | |
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58 | 127.0.0.1 localhost |
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59 | ::1 localhost |
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60 | <replaceable>[192.168.1.1]</replaceable> <replaceable>[<HOSTNAME>.example.org]</replaceable> <replaceable>[HOSTNAME]</replaceable> <replaceable>[alias ...]</replaceable> |
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61 | |
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62 | # End /etc/hosts (network card version)</literal> |
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63 | EOF</userinput></screen> |
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64 | |
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65 | <para>The <replaceable>[192.168.1.1]</replaceable> and |
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66 | <replaceable>[<HOSTNAME>.example.org]</replaceable> |
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67 | values need to be changed for specific users or requirements (if |
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68 | assigned an IP address by a network/system administrator and the |
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69 | machine will be connected to an existing network). The optional |
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70 | alias name(s) can be omitted.</para> |
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71 | |
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72 | <para>If a network card is not going to be configured, create the |
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73 | <filename>/etc/hosts</filename> file by running:</para> |
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74 | |
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75 | <screen role="nodump"><userinput>cat > /etc/hosts << "EOF" |
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76 | <literal># Begin /etc/hosts (no network card version) |
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77 | |
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78 | 127.0.0.1 <replaceable>[<HOSTNAME>.example.org]</replaceable> <replaceable>[HOSTNAME]</replaceable> localhost |
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79 | ::1 localhost |
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80 | |
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81 | # End /etc/hosts (no network card version)</literal> |
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82 | EOF</userinput></screen> |
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83 | |
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84 | <para>The ::1 entry is the IPv6 counterpart of 127.0.0.1 and represents the |
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85 | IPv6 loopback interface.</para> |
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86 | |
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87 | </sect1> |
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