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226 lines
8.1 KiB
XML
226 lines
8.1 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>Shorewall and Linux-vserver</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>2010</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>Introduction</title>
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<para>Formal support for Linux-vserver was added in Shorewall 4.4.11
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Beta2. The centerpiece of that support is the
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<firstterm>vserver</firstterm> zone type. Vserver zones have the following
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characteristics:</para>
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<itemizedlist>
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<listitem>
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<para>They are defined on the Linux-vserver host.</para>
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</listitem>
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<listitem>
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<para>The $FW zone is their implicit parent.</para>
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</listitem>
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<listitem>
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<para>Their contents must be defined using the <ulink
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url="manpages/shorewall-hosts.html">shorewall-hosts </ulink>(5) file.
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The <emphasis role="bold">ipsec</emphasis> option may not be
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specified.</para>
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</listitem>
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<listitem>
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<para>They may not appear in the ZONE column of the <ulink
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url="manpages/shorewall-interfaces.html">shorewall-interfaces</ulink>
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(5) file.</para>
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</listitem>
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</itemizedlist>
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<para>Note that you don't need to run Vservers to use vserver zones; they
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may also be used to create a firewall sub-zone for each <ulink
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url="Shorewall_and_Aliased_Interfaces.html">aliased
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interface</ulink>.</para>
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<para>If you use these zones, keep in mind that Linux-vserver implements a
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very weak form of network virtualization:</para>
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<itemizedlist>
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<listitem>
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<para>From a networking point of view, vservers live on the host
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system. So if you don't use care, Vserver traffic to/from zone z will
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be controlled by the fw->z and z->fw rules and policies rather
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than by vserver->z and z->vserver rules and policies.</para>
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</listitem>
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<listitem>
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<para>Outgoing connections from a vserver will not use the Vserver's
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address as the SOURCE IP address unless you configure applications
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running in the Vserver properly. This is especially true for IPv6
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applications. Such connections will appear to come from the $FW zone
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rather than the intended Vserver zone.</para>
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</listitem>
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<listitem>
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<para>While you can define the vservers to be associated with the
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network interface where their IP addresses are added at vserver
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startup time, Shorewall internally associates all vservers with the
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loopback interface (<emphasis role="bold">lo</emphasis>). Here's an
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example of how that association can show up:</para>
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<programlisting>gateway:~# shorewall show zones
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Shorewall 4.4.11-Beta2 Zones at gateway - Fri Jul 2 12:26:30 PDT 2010
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fw (firewall)
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drct (ipv4)
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eth4:+drct_eth4
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loc (ipv4)
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eth4:0.0.0.0/0
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net (ipv4)
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eth1:0.0.0.0/0
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vpn (ipv4)
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tun+:0.0.0.0/0
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dmz (<emphasis role="bold">vserver</emphasis>)
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<emphasis role="bold">lo</emphasis>:70.90.191.124/31
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gateway:~#</programlisting>
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</listitem>
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</itemizedlist>
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</section>
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<section>
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<title>Vserver Zones</title>
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<para>This is a diagram of the network configuration here at Shorewall.net
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during the summer of 2010:</para>
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<graphic align="center" fileref="images/Network2010a.png"/>
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<para>I created a zone for the vservers as follows:</para>
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<para><filename>/etc/shorewall/zones</filename>:</para>
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<programlisting>#ZONE TYPE OPTIONS ...
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fw firewall
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loc ip #Local Zone
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drct:loc ipv4 #Direct internet access
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net ipv4 #Internet
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vpn ipv4 #OpenVPN clients
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<emphasis role="bold">dmz vserver #Vservers</emphasis></programlisting>
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<para><filename>/etc/shorewall/interfaces</filename>:</para>
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<programlisting>?FORMAT 2
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#ZONE INTERFACE OPTIONS
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<emphasis role="bold">net eth1 routeback,dhcp,optional,routefilter=0,logmartians,proxyarp=0,nosmurfs,upnp</emphasis>
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...</programlisting>
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<para><filename>/etc/shorewall/hosts</filename>:</para>
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<programlisting>#ZONE HOST(S) OPTIONS
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drct eth4:dynamic
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<emphasis role="bold">dmz eth1:70.90.191.124/31 routeback</emphasis></programlisting>
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<para>While the IP addresses 70.90.191.124 and 70.90.191.125 are
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configured on eth1, the actual interface name is irrelevant so long as the
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interface is defined in <ulink
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url="manpages/shorewall-interfaces.html">shorewall-interfaces</ulink> (5).
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Shorewall will consider all vserver zones to be associated with the
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loopback interface (<emphasis role="bold">lo</emphasis>). Note that the
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<emphasis role="bold">routeback</emphasis> option is required if the
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vservers are to be able to communicate with each other.</para>
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<para>Once a vserver zone is defined, it can be used like any other zone
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type.</para>
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<para>Here is the corresponding IPv6 configuration.</para>
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<para><filename>/etc/shorewall6/zones</filename></para>
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<programlisting>#ZONE TYPE OPTIONS IN_OPTIONS OUT_OPTIONS
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fw firewall
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net ipv6
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loc ipv6
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vpn ipv6
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<emphasis role="bold">dmz vserver</emphasis>
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</programlisting>
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<para><filename>/etc/shorewall6/interfaces</filename>:</para>
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<programlisting>?FORMAT 2
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#ZONE INTERFACE OPTIONS
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<emphasis role="bold">net sit1 tcpflags,forward=1,nosmurfs,routeback</emphasis>
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...</programlisting>
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<para><filename>/etc/shorewall6/hosts</filename>:</para>
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<programlisting>#ZONE HOST(S) OPTIONS
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<emphasis role="bold">dmz sit1:[2001:470:e857:1::/64]</emphasis></programlisting>
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<para>Note that I choose to place the Vservers on sit1 (the IPv6 net
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interface) rather than on eth1. Again, it really doesn't matter
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much.</para>
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</section>
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<section id="NDP">
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<title>Sharing an IPv6 /64 between Vservers and a LAN</title>
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<para>I have both a /64 (2001:470:b:227::/64) and a /48
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(2001:470:e857::/48) from <ulink
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url="http://www.tunnelbroker.net">Hurricane Electric</ulink>. When I first
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set up my Vserver configuration, I assigned addresses from the /48 to the
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Vservers as shown above.</para>
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<para>Given that it is likely that when native IPv6 is available from my
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ISP, I will only be able to afford a single /64, in February 2011 I
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decided to migrate my vservers to the /64. This was possible because of
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Proxy NDP support in Shorewall 4.4.16 and later. The new network diagram
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is as shown below:</para>
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<graphic align="center" fileref="images/Network2011.png"/>
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<para>This change was accompanied by the following additions to
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<filename>/etc/shorewall6/proxyndp</filename>:</para>
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<programlisting>#ADDRESS INTERFACE EXTERNAL HAVEROUTE PERSISTENT
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2001:470:b:227::2 - eth4 Yes Yes
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2001:470:b:227::3 - eth4 Yes Yes
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</programlisting>
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<para>These two entries allow the firewall to respond to NDP requests for
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the two Vserver IPv6 addresses received on interface eth4.</para>
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<para>As part of this change, the <emphasis role="bold">Lists</emphasis>
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vserver (OpenSuSE 10.3 was retired in favor of <emphasis
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role="bold">Mail</emphasis> (Debian Squeeze).</para>
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</section>
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</article>
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