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157 lines
5.0 KiB
XML
157 lines
5.0 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>LXC and Shorewall</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>2011</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>Background</title>
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<para>LXC (<ulink
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url="http://lxc.sourceforge.net/">http://lxc.sourceforge.net/</ulink>) is
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a set of user-space tools for managing the container capabilities that
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have been in the Linux Kernel since 2.6.27.</para>
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<para>This short article describes how I've implemented LXC here at
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shorewall.net, with emphasis on the networking and firewall
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aspects.</para>
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</section>
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<section>
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<title>Overview of a Working Configuration</title>
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<para>The following diagram shows the network at shorewall.net in the
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spring of 2011.</para>
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<graphic align="center" fileref="images/Network2011a.png" />
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<para>As shown in that diagram, the LXC containers are bridged to br0.
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Here are the relevant configuration entries.</para>
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<para><filename>/etc/network/interfaces:</filename></para>
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<programlisting>#
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# LXC bridge
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#
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auto br0
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iface br0 inet static
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bridge_ports none
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bridge_fd 0
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address 70.90.191.121
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broadcast 0.0.0.0
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netmask 255.255.255.255
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post-up ip route add 70.90.191.124/31 dev br0
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iface br0 inet6 static
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address 2001:470:b:227::41
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netmask 124
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</programlisting>
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<para><filename>/etc/lxc/mail.conf</filename><programlisting>lxc.network.type=veth
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lxc.network.link=br0
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lxc.network.flags=up
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lxc.network.ipv4=70.90.191.124/29
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lxc.network.ipv6=2001:470:b:227::42/124
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…</programlisting></para>
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<para><filename>/etc/lxc/server.conf</filename><programlisting>lxc.network.type=veth
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lxc.network.link=br0
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lxc.network.flags=up
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lxc.network.ipv4=70.90.191.125/29
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lxc.network.ipv6=2001:470:b:227::43/124
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…</programlisting></para>
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<para>Note that I have subnetted 2001:470:b:227::/64 with a /124
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(2001:470:b:227::40/124) assigned to the bridge. To make those addresses
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accessible from the LOC zone, the following entries are required in
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/etc/shorewall6/proxyndp:</para>
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<programlisting>#ADDRESS INTERFACE EXTERNAL HAVEROUTE PERSISTENT
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2001:470:b:227::41 - eth1 Yes Yes
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2001:470:b:227::42 - eth1 Yes Yes
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2001:470:b:227::43 - eth1 Yes Yes
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</programlisting>
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<para>The entries in the LXC .conf files are expected to configure eth0 in
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the LXC containers; they do, <emphasis>sort of</emphasis>. In both of the
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containers, no ipv6 default route was assigned. I corrected that by adding
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this entry in <filename>/etc/sysctl.conf</filename> in both
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containers:</para>
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<programlisting>net.ipv6.conf.all.forwarding=0
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</programlisting>
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<para>I then added this stanza to <filename>/etc/radvd.conf</filename> on
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the host:</para>
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<programlisting>interface br0{
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AdvSendAdvert on;
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MinRtrAdvInterval 300;
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MaxRtrAdvInterval 505;
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AdvDefaultLifetime 9000;
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route ::/0 {
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AdvRouteLifetime infinity;
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};
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};
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</programlisting>
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<para>Curiosly, LXC gives container mail's eth0 this somewhat odd
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configuration, and fails to add a default ipv4 route:</para>
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<programlisting>14: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
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link/ether 4e:56:66:11:3c:6b brd ff:ff:ff:ff:ff:ff
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inet 70.90.191.124/29 <emphasis role="bold">brd 70.90.191.120</emphasis> scope global eth0
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inet6 2001:470:b:227::42/124 scope global
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valid_lft forever preferred_lft forever
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inet6 fe80::4c56:66ff:fe11:3c6b/64 scope link
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valid_lft forever preferred_lft forever
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</programlisting>
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<para>So in that container's<filename> /etc/rc.local</filename>, I also
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have:</para>
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<programlisting>ip route add default via 70.90.191.121</programlisting>
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<para>With the exception of the entries in
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<filename>/etc/shorewall6/proxyndp</filename>. the Shorewall and
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Shorewall6 configurations are fairly conventional three-interface setups.
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In both configurations, the <filename>interfaces</filename> file entry for
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br0 has the <option>routeback</option> option specified.</para>
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</section>
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</article>
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