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git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@8670 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
135 lines
4.7 KiB
XML
135 lines
4.7 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
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"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
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<article>
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<!--$Id$-->
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<articleinfo>
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<title>Simple way to set up Split DNS</title>
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<authorgroup>
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<author>
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<firstname>Tom</firstname>
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<surname>Eastep</surname>
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</author>
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</authorgroup>
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<pubdate><?dbtimestamp format="Y/m/d"?></pubdate>
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<copyright>
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<year>2008</year>
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<holder>Thomas M. Eastep</holder>
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</copyright>
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<legalnotice>
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<para>Permission is granted to copy, distribute and/or modify this
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document under the terms of the GNU Free Documentation License, Version
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1.2 or any later version published by the Free Software Foundation; with
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no Invariant Sections, with no Front-Cover, and with no Back-Cover
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Texts. A copy of the license is included in the section entitled
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<quote><ulink url="GnuCopyright.htm">GNU Free Documentation
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License</ulink></quote>.</para>
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</legalnotice>
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</articleinfo>
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<section>
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<title>What is Split DNS</title>
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<para><firstterm>Split DNS</firstterm> is simply a configuration in which
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the IP address to which a DNS name resolves is dependent on the location
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of the client. It is most often used in a NAT environment to insure that
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local clients resolve the DNS names of local servers to their RFC 1918
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addresses while external clients resolve the same server names to their
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public counterparts.</para>
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</section>
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<section>
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<title>Why would I want to use Split DNS?</title>
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<para>See <ulink url="FAQ.htm#faq2">Shorewall FAQ 2</ulink>.</para>
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</section>
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<section>
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<title>Setting up Split DNS</title>
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<para>Setting up Split DNS is extremely simple:</para>
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<orderedlist>
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<listitem>
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<para>Be sure that your firewall/router can resolve external DNS
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names.</para>
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</listitem>
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<listitem>
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<para>Install the <emphasis role="bold">dnsmasq</emphasis> package
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(<ulink
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url="http://www.thekelleys.org.uk/dnsmasq/doc.html">http://www.thekelleys.org.uk/dnsmasq/doc.htm</ulink>l)
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and arrange for it to start at boot time. There are many dnsmasq
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HOWTOs on the Internet.</para>
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</listitem>
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<listitem>
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<para>Add your local hosts to <filename>/etc/hosts</filename> on the
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firewall/router using their local RFC 1918 addresses. Here's an
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example:<programlisting>#
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# hosts This file describes a number of hostname-to-address
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# mappings for the TCP/IP subsystem. It is mostly
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# used at boot time, when no name servers are running.
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# On small systems, this file can be used instead of a
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# "named" name server.
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# Syntax:
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#
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# IP-Address Full-Qualified-Hostname Short-Hostname
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#
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127.0.0.1 localhost
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# special IPv6 addresses
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::1 localhost ipv6-localhost ipv6-loopback
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fe00::0 ipv6-localnet
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ff00::0 ipv6-mcastprefix
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ff02::1 ipv6-allnodes
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ff02::2 ipv6-allrouters
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ff02::3 ipv6-allhosts
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127.0.0.2 ursa.shorewall.net ursa
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<emphasis role="bold">172.20.1.1 linksys.shorewall.net linksys
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192.168.0.1 opensuse.shorewall.net opensuse
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192.168.0.2 debian.shorewall.net debian
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192.168.0.3 ubuntu.shorewall.net ubuntu
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192.168.0.4 fedora.shoreawll.net fedora
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192.168.0.5 opensuse11.shorewall.net opensuse11
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192.168.0.6 centos.shorewall.net centos
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192.168.0.7 debian32.shorewall.net debian32
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192.168.0.8 fedora9.shorewall.net fedora9</emphasis>
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206.124.146.254 blarg.shorewall.net blarg
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</programlisting></para>
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</listitem>
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<listitem>
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<para>Configure your local network hosts to use the firewall/router as
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their DNS server. If your local hosts are configured using DHCP, that
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is a simple one-line change to the DHCP configuration.</para>
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</listitem>
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</orderedlist>
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<para><emphasis role="bold">And that's it!</emphasis> Your local clients
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will resolve those names in the firewall/router's
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<filename>/etc/hosts</filename> file as defined in that file. All other
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names will be resolved using the firewall/router's Name Server as defined
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in <filename>/etc/resolv.conf</filename>.</para>
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<para>Example:</para>
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<para>From an Internet Host:<programlisting>gateway:~ # host linksys.shorewall.net
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linksys.shorewall.net has address 206.124.146.180
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gateway:~ # </programlisting></para>
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<para>From ubuntu (192.168.0.3):<programlisting>teastep@ubuntu:~$ host linksys
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linksys.shorewall.net has address 172.20.1.1
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teastep@ubuntu:~$ </programlisting></para>
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</section>
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</article> |