forked from extern/shorewall_code
fc4a43e2ac
git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@1077 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
104 lines
3.8 KiB
XML
104 lines
3.8 KiB
XML
<?xml version="1.0" encoding="UTF-8"?>
|
|
<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
|
|
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
|
|
<article>
|
|
<!--$Id$-->
|
|
|
|
<articleinfo>
|
|
<title>DHCP</title>
|
|
|
|
<authorgroup>
|
|
<author>
|
|
<firstname>Tom</firstname>
|
|
|
|
<surname>Eastep</surname>
|
|
</author>
|
|
</authorgroup>
|
|
|
|
<pubdate>2004-01-10</pubdate>
|
|
|
|
<copyright>
|
|
<year>2001</year>
|
|
|
|
<year>2002</year>
|
|
|
|
<year>2004</year>
|
|
|
|
<holder>Thomas M. Eastep</holder>
|
|
</copyright>
|
|
|
|
<legalnotice>
|
|
<para>Permission is granted to copy, distribute and/or modify this
|
|
document under the terms of the GNU Free Documentation License, Version
|
|
1.2 or any later version published by the Free Software Foundation; with
|
|
no Invariant Sections, with no Front-Cover, and with no Back-Cover
|
|
Texts. A copy of the license is included in the section entitled
|
|
<quote><ulink url="GnuCopyright.htm">GNU Free Documentation License</ulink></quote>.</para>
|
|
</legalnotice>
|
|
</articleinfo>
|
|
|
|
<note>
|
|
<para>For most operations, DHCP software interfaces to the Linux IP stack
|
|
at a level below Netfilter. Hence, Netfilter (and therefore Shorewall)
|
|
cannot be used effectively to police DHCP. The <quote>dhcp</quote>
|
|
interface option described in this article allows for Netfilter to stay
|
|
out of DHCP's way for those operations that can be controlled by
|
|
Netfilter and prevents unwanted logging of DHCP-related traffic by
|
|
Shorewall-generated Netfilter logging rules.</para>
|
|
</note>
|
|
|
|
<section>
|
|
<title>If you want to Run a DHCP Server on your firewall</title>
|
|
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>Specify the <quote>dhcp</quote> option on each interface to be
|
|
served by your server in the <filename><ulink
|
|
url="Documentation.htm#Interfaces">/etc/shorewall/interfaces</ulink></filename>
|
|
file. This will generate rules that will allow DHCP to and from your
|
|
firewall system.</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>When starting <quote>dhcpd</quote>, you need to list those
|
|
interfaces on the run line. On a RedHat system, this is done by
|
|
modifying <filename>/etc/sysconfig/dhcpd</filename>.</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
</section>
|
|
|
|
<section>
|
|
<title>If a Firewall Interface gets its IP Address via DHCP</title>
|
|
|
|
<itemizedlist>
|
|
<listitem>
|
|
<para>Specify the <quote>dhcp</quote> option for this interface in the
|
|
<ulink url="Documentation.htm#Interfaces"><filename>/etc/shorewall/interfaces</filename></ulink>
|
|
file. This will generate rules that will allow DHCP to and from
|
|
your firewall system.</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>If you know that the dynamic address is always going to be in
|
|
the same subnet, you can specify the subnet address in the
|
|
interface's entry in the <ulink url="Documentation.htm#Interfaces"><filename>/etc/shorewall/interfaces</filename></ulink>
|
|
file.</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>If you don't know the subnet address in advance, you should
|
|
specify <quote>detect</quote> for the interface's subnet address
|
|
in the <ulink url="Documentation.htm#Interfaces"><filename>/etc/shorewall/interfaces</filename></ulink>
|
|
file and start Shorewall after the interface has started.</para>
|
|
</listitem>
|
|
|
|
<listitem>
|
|
<para>In the event that the subnet address might change while
|
|
Shorewall is started, you need to arrange for a <quote>shorewall
|
|
refresh</quote> command to be executed when a new dynamic IP address
|
|
gets assigned to the interface. Check your DHCP client's
|
|
documentation.</para>
|
|
</listitem>
|
|
</itemizedlist>
|
|
</section>
|
|
</article> |