shorewall_code/docs/XenMyWay-Routed.xml

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  <articleinfo>
    <title>Strong Firewall in a Routed Xen Dom0</title>

    <authorgroup>
      <author>
        <firstname>Tom</firstname>

        <surname>Eastep</surname>
      </author>
    </authorgroup>

    <pubdate><?dbtimestamp format="Y/m/d"?></pubdate>

    <copyright>
      <year>2006</year>

      <year>2007</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, no Front-Cover Texts, and 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>

  <caution>
    <para>This article applies to Shorewall 4.0 and later. If you are running
    a version of Shorewall earlier than Shorewall 4.0.0 then please see the
    documentation for that release.</para>
  </caution>

  <section id="Before">
    <title>Before Xen</title>

    <para>Prior to adopting Xen, I had a home office crowded with 5 systems,
    three monitors a scanner and a printer. The systems were:</para>

    <orderedlist>
      <listitem>
        <para>Firewall</para>
      </listitem>

      <listitem>
        <para>Public Server in a DMZ (mail)</para>
      </listitem>

      <listitem>
        <para>Private Server (wookie)</para>
      </listitem>

      <listitem>
        <para>My personal Linux Desktop (ursa)</para>
      </listitem>

      <listitem>
        <para>My work system (docked laptop running Windows XP).</para>
      </listitem>
    </orderedlist>

    <para>The result was a very crowded and noisy room.</para>
  </section>

  <section id="After">
    <title>After Xen</title>

    <para>Xen has allowed me to reduce the noise and clutter considerably. I
    now have three systems with two monitors. I've also replaced the
    individual printer and scanner with a Multifunction
    FAX/Scanner/Printer.</para>

    <para>The systems now include:</para>

    <orderedlist>
      <listitem>
        <para>Combination Firewall/Public Server/Private Server/Wireless
        Gateway using Xen (created by building out my Linux desktop system --
        Now replaced by a Hewlett-Packard Pavilion a1510y).</para>
      </listitem>

      <listitem>
        <para>My work system.</para>
      </listitem>

      <listitem>
        <para>My Linux desktop (wookie, which is actually the old public
        server box)</para>
      </listitem>
    </orderedlist>

    <para>The Linux systems run either <trademark>OpenSuSE </trademark>10.3 or
    <trademark>Ubuntu</trademark> "Gutsy Gibbon".</para>

    <para>Here is a high-level diagram of our network.</para>

    <graphic align="center" fileref="images/Xen5.png"/>

    <para>As shown in this diagram, the Xen system has three physical network
    interfaces. These are:</para>

    <itemizedlist>
      <listitem>
        <para><filename class="devicefile">eth0</filename> -- connected to our
        DSL "Modem".</para>
      </listitem>

      <listitem>
        <para><filename class="devicefile">eth1</filename> -- connected to the
        switch in my office.</para>
      </listitem>

      <listitem>
        <para><filename class="devicefile">eth2</filename> -- connected to a
        Wireless Access Point (WAP) that interfaces to our wireless
        network.</para>
      </listitem>
    </itemizedlist>

    <para>There are three Xen domains.</para>

    <orderedlist>
      <listitem>
        <para>Dom0 (DNS name <emphasis
        role="bold">gateway.shorewall.net</emphasis>) is used as our main
        firewall and wireless gateway as well as a local file server. It hosts
        <ulink url="Shorewall_Squid_Usage.html">Squid</ulink> running as a
        transparent HTTP proxy and a DHCP server that manages IP address
        assignment for both the LAN and the Wireless network.</para>
      </listitem>

      <listitem>
        <para>A DomU (Domain name <emphasis role="bold">lists</emphasis>, DNS
        name <emphasis role="bold">lists.shorewall.net</emphasis>) that is
        used as a public Web/FTP/Mail/DNS server.</para>
      </listitem>

      <listitem>
        <para>A DomU (Domain name <emphasis role="bold">test</emphasis>, DNS
        name <emphasis role="bold">test.shorewall.net</emphasis>) that I use
        for Shorewall testing.</para>
      </listitem>
    </orderedlist>

    <para>Shorewall runs in Dom0.</para>

    <caution>
      <para>As the developer of Shorewall, I have enough experience to be very
      comfortable with Linux networking and Shorewall/iptables. I arrived at
      this configuration after a fair amount of trial and error
      experimentation (see <ulink url="XenMyWay.html">Xen and the art of
      Consolidation</ulink>). If you are a Linux networking novice, I
      recommend that you do not attempt a configuration like this one for your
      first Shorewall installation. You are very likely to frustrate both
      yourself and the Shorewall support team. Rather I suggest that you start
      with something simple like a <ulink url="standalone.htm">standalone
      installation</ulink> in a DomU; once you are comfortable with that then
      you will be ready to try something more substantial.</para>

      <para>As Paul Gear says: <emphasis>Shorewall might make iptables easy,
      but it doesn't make understanding fundamental networking principles,
      traffic shaping, or multi-ISP routing any easier</emphasis>.</para>

      <para>The same goes for Xen networking.</para>
    </caution>

    <section id="Domains">
      <title>Domain Configuration</title>

      <para>Below are the relevant configuration files for the two domains. I
      use a partition on my hard drives for the DomU storage device.</para>

      <para>There is not much documentation about how to configure Xen for
      routed operation. I've tried to mark the relevant parts with <emphasis
      role="bold">bold font</emphasis>.<important>
          <para>The files from <filename
          class="directory">/etc/xen/auto</filename> shown below correspond to
          my configuration under Xen 3.0. I'm now running Xen 3.1 which does
          not use configuration files for the domains but rather keeps the
          configuration in a database managed by xend. See <link
          linkend="Xen3.1">below</link>.</para>
        </important></para>

      <blockquote>
        <para><filename>/boot/grub/menu.lst</filename> — here is the entry
        that boots Xen in Dom0.</para>

        <blockquote>
          <programlisting>title Kernel-2.6.18.8-0.1-xen
    root (hd0,5)
    kernel /boot/xen.gz 
    module /boot/vmlinuz-2.6.18.8-0.1-xen root=/dev/sda6 vga=0x31a resume=/dev/sda5 splash=silent showopts
    module /boot/initrd-2.6.18.8-0.1-xen</programlisting>
        </blockquote>

        <para><filename>/etc/modprobe.conf.local</filename> (This may need to
        go in <filename>/etc/modprobe.conf</filename> or
        <filename>/etc/modprobe.d/options</filename> on your system)</para>

        <para><blockquote>
            <programlisting><emphasis role="bold">options netloop nloopbacks=0</emphasis> #Stop netloop from creating 8 useless vifs</programlisting>
          </blockquote></para>

        <para><filename>/etc/xen/auto/01-lists</filename> — configuration file
        for the lists domain. Placed in <filename
        class="directory">/etc/xen/auto/</filename> so it is started
        automatically by Xen's <emphasis>xendomains</emphasis> service.</para>

        <blockquote>
          <programlisting>disk = [ 'phy:/dev/sda9,hda,w', 'phy:/dev/hda,hdb,r' ]
memory = 512
vcpus = 1
builder = 'linux'
name = 'server'
vif = [ 'mac=00:16:3e:b1:d7:90, <emphasis role="bold">ip=206.124.146.177, vifname=eth3</emphasis>' ]
localtime = 0
on_poweroff = 'destroy'
on_reboot = 'restart'
on_crash = 'restart'
extra = ' TERM=xterm'
bootloader = '/usr/lib/xen/boot/domUloader.py'
bootentry = 'hda2:/boot/vmlinuz-xen,/boot/initrd-xen'</programlisting>

          <para>Note that the vifname is set to 'eth3' for the virtual
          interface to this DomU. This will cause the Dom0 interface to the
          server to have a fixed name (<filename
          class="devicefile">eth3</filename>) which makes it a lot easier to
          deal with in Shorewall and elsewhere.</para>

          <para>Specifying an IP address (ip=206.124.146.177) causes the
          vif-route script to create a host route to that IP address on
          <filename class="devicefile">eth3</filename>.</para>

          <blockquote>
            <programlisting>gateway:~ # <command>ip route ls dev eth3</command>
206.124.146.177  scope link  src 206.124.146.176
gateway:~ #</programlisting>
          </blockquote>

          <para>Note that the source for the route is 206.124.146.176. That is
          the primary IP address of Dom0's <filename
          class="devicefile">eth0</filename>. Xen configures <filename
          class="devicefile">eth3</filename> to have that same IP
          address.</para>
        </blockquote>

        <para><filename>/etc/xen/auto/02-test</filename> — configuration file
        for the test domain.</para>

        <blockquote>
          <programlisting>disk = [ 'phy:/dev/hdb4,hda,w', 'phy:/dev/hda,hdb,r' ]
memory = 512
vcpus = 1
builder = 'linux'
name = 'test'
vif = [ 'mac=00:16:3e:83:ad:28, <emphasis role="bold">ip=192.168.1.7</emphasis>, <emphasis
              role="bold">vifname=eth4</emphasis>' ]
localtime = 0
on_poweroff = 'destroy'
on_reboot = 'restart'
on_crash = 'restart'
extra = ' TERM=xterm'
bootloader = '/usr/lib/xen/boot/domUloader.py'
bootentry = 'hda2:/boot/vmlinuz-xen,/boot/initrd-xen'
</programlisting>
        </blockquote>

        <para>Excerpt from
        <filename>/etc/xen/xend-config.sxp</filename>:<blockquote>
            <programlisting>…

# It is possible to use the network-bridge script in more complicated
# scenarios, such as having two outgoing interfaces, with two bridges, and
# two fake interfaces per guest domain.  To do things like this, write
# yourself a wrapper script, and call network-bridge from it, as appropriate.
#
<emphasis role="bold">#</emphasis>(network-script network-bridge)

…

# If you are using only one bridge, the vif-bridge script will discover that,
# so there is no need to specify it explicitly.
#
<emphasis role="bold">#</emphasis>(vif-script vif-bridge)

## Use the following if network traffic is routed, as an alternative to the
# settings for bridged networking given above.
<emphasis role="bold">(network-script network-route)
(vif-script     vif-route)</emphasis>
</programlisting>

            <important>
              <para>As of this writing, the vif-route script does not set up
              Proxy ARP correctly. So the domU can communicate with the dom0
              but not with hosts beyond the dom0.</para>

              <para>If you configure Shorewall as described below, Shorewall
              will correct the Proxy ARP configuration so that it will
              work.</para>
            </important>
          </blockquote></para>
      </blockquote>

      <para id="Xen3.1">Instructions for editing entries in the Xen 3.1 xend
      database may be found at <ulink
      url="http://www.novell.com/documentation/vmserver/config_options/index.html?page=/documentation/vmserver/config_options/data/b8uh3zr.html">http://www.novell.com/documentation/vmserver/config_options/index.html?page=/documentation/vmserver/config_options/data/b8uh3zr.html</ulink>,
      The following are excerpts from the XML representations of the two user
      domains (produced by "xm list -l …").</para>

      <para>lists domain:<blockquote>
          <para><programlisting>… 
    (features )
<emphasis role="bold">    (on_xend_start start)
    (on_xend_stop shutdown)</emphasis>
    (start_time 1194710550.49)
 …
    (console_mfn 397179)
    (device
        (vif
<emphasis role="bold">            (mac 00:16:3e:b1:d7:90)
            (script vif-route)
            (ip 206.124.146.177)
            (vifname eth3)</emphasis>
            (type netfront)
            (devid 0)
            (uuid 55676385-7b69-09fd-4027-751b692ead75)
        )
    )
    (device
        (vbd
 …</programlisting></para>
        </blockquote></para>

      <para>test domain:<blockquote>
          <para><programlisting>… 
   (console_mfn 418003)
    (device
        (vif
            (uuid 64a1dd48-fa8b-7561-e90b-cd589cbeb7fa)
<emphasis role="bold">            (script vif-route)
            (ip 192.168.1.7)
            (mac 00:16:3e:83:ad:28)
            (vifname eth4)
</emphasis>            (devid 0)
            (type netfront)
            (backend 0)
        )
    )
    (device
        (vbd
…</programlisting></para>
        </blockquote></para>

      <para>With the three Xen domains up and running, the system looks as
      shown in the following diagram.</para>

      <graphic align="center" fileref="images/Xen4a.png"/>

      <para>The zones correspond to the Shorewall zones in the Dom0
      configuration.</para>

      <para>Readers who are paying attention will notice that eth4 has the
      same public IP address (206.124.146.176) as eth0 (and eth3), yet the
      <emphasis role="bold">test</emphasis> system connected to that interface
      has an RFC 1918 address (192.168.1.7). That configuration is established
      by Xen which clones the primary IP address of eth0 on all of the routed
      virtual interfaces that it creates. <emphasis
      role="bold">test</emphasis> is configured with its default route via
      192.168.1.254 which is the IP address of the firewall's br0. That works
      because of the way that the Linux network stack treats local IPv4
      addresses; by default, it will respond to ARP "who-has" broadcasts for
      any local address and not just for the addresses on the interface that
      received the broadcast (but of course the MAC address returned in the
      "here-is" response is that of the interface that received the
      broadcast). So when <emphasis role="bold">test</emphasis> broadcasts
      "who-has 192.168.1.254", the firewall responds with "here-is
      192.168.1.254 00:16:3e:83:ad:28" (00:16:3e:83:ad:28 is the MAC of
      virtual interface eth4).</para>

      <caution>
        <para>Under some circumstances, UDP and/or TCP communication from a
        DomU won't work for no obvious reason. That happened with the
        <emphasis role="bold">lists</emphasis> domain in my setup. Looking at
        the IP traffic with <command>tcpdump -nvvi eth1</command> in Dom0
        showed that UDP packets from the <emphasis
        role="bold">lists</emphasis> DomU had incorrect checksums. That
        problem was corrected by arranging for the following command to be
        executed in the <emphasis role="bold">lists</emphasis> and <emphasis
        role="bold">test</emphasis> domains when the <filename
        class="devicefile">eth0</filename> device was brought up:</para>

        <para><command>ethtool -K eth0 tx off</command></para>

        <para>Under <trademark>OpenSuSE</trademark> 10.2, I placed the
        following in
        <filename><filename>/etc/sysconfig/network/ifcfg-eth-id-00:16:3e:b1:d7:90</filename></filename>
        (the config file for eth0):</para>

        <programlisting>ETHTOOL_OPTIONS='-K iface tx off'</programlisting>

        <para>Under other distributions, the technique will vary. For example,
        under <trademark>Debian</trademark> or <trademark>Ubuntu</trademark>,
        you can just add a 'post-up' entry to
        <filename>/etc/network/interfaces</filename> as shown here:</para>

        <programlisting> iface eth0 inet static
         address 206.124.146.177
         netmask 255.255.255.0
         <emphasis role="bold">post-up ethtool -K eth0 tx off</emphasis></programlisting>
      </caution>

      <caution>
        <para>Update. Under OpenSuSE 10.2, communication from a domU works
        okay without running ethtool <emphasis role="bold">but traffic shaping
        in dom0 doesn't work!</emphasis> So it's a good idea to run it just to
        be safe.</para>
      </caution>
    </section>

    <section id="Firewall">
      <title>Dom0 Shorewall Configuration</title>

      <para>In Dom0, I run a conventional three-interface firewall with Proxy
      ARP DMZ -- it is very similar to the firewall described in the <ulink
      url="shorewall_setup_guide.htm">Shorewall Setup Guide</ulink> with the
      exception that I've added a fourth interface for our wireless network.
      The firewall runs a routed <ulink url="OPENVPN.html">OpenVPN
      server</ulink> to provide road warrior access for our three laptops and
      a bridged OpenVPN server for the wireless network in our home. Here is
      the firewall's view of the network:</para>

      <graphic align="center" fileref="images/network4a.png"/>

      <para>The three laptops can be directly attached to the LAN as shown
      above or they can be attached wirelessly -- their IP addresses are the
      same in either case; when they are directly attached, the IP address is
      assigned by the DHCP server running in Dom0 and when they are attached
      wirelessly, the IP address is assigned by OpenVPN.</para>

      <para>The Shorewall configuration files are shown below. All routing and
      secondary IP addresses are handled in the OpenSuSE network
      configuration.</para>

      <blockquote>
        <para>/etc/shorewall/shorewall.conf</para>

        <programlisting>STARTUP_ENABLED=Yes
VERBOSITY=0
SHOREWALL_COMPILER=perl
LOGFILE=/var/log/firewall
LOGFORMAT="Shorewall:%s:%s:"
LOGTAGONLY=No
LOGRATE=
LOGBURST=
LOGALLNEW=
BLACKLIST_LOGLEVEL=
MACLIST_LOG_LEVEL=$LOG
TCP_FLAGS_LOG_LEVEL=$LOG
SMURF_LOG_LEVEL=$LOG
LOG_MARTIANS=No
IPTABLES=
SHOREWALL_SHELL=/bin/ash
SUBSYSLOCK=/var/lock/subsys/shorewall
MODULESDIR=
CONFIG_PATH=/etc/shorewall:/usr/share/shorewall
RESTOREFILE=
IPSECFILE=zones
LOCKFILE=
DROP_DEFAULT="Drop"
REJECT_DEFAULT="Reject"
ACCEPT_DEFAULT="none"
QUEUE_DEFAULT="none"
IP_FORWARDING=Yes
ADD_IP_ALIASES=No
ADD_SNAT_ALIASES=No
RETAIN_ALIASES=No
TC_ENABLED=internal
TC_EXPERT=No
CLEAR_TC=Yes
MARK_IN_FORWARD_CHAIN=Yes
CLAMPMSS=Yes
ROUTE_FILTER=No
DETECT_DNAT_IPADDRS=Yes
MUTEX_TIMEOUT=60
ADMINISABSENTMINDED=Yes
BLACKLISTNEWONLY=Yes
DELAYBLACKLISTLOAD=No
MODULE_SUFFIX=
DISABLE_IPV6=Yes
BRIDGING=No
DYNAMIC_ZONES=No
PKTTYPE=No
MACLIST_TABLE=mangle
MACLIST_TTL=60
SAVE_IPSETS=No
MAPOLDACTIONS=No
FASTACCEPT=Yes
IMPLICIT_CONTINUE=Yes
HIGH_ROUTE_MARKS=Yes
USE_ACTIONS=Yes
OPTIMIZE=1
EXPORTPARAMS=No
EXPAND_POLICIES=Yes
KEEP_RT_TABLES=No
DELETE_THEN_ADD=No
BLACKLIST_DISPOSITION=DROP
MACLIST_DISPOSITION=DROP
TCP_FLAGS_DISPOSITION=DROP</programlisting>

        <para><filename>/etc/shorewall/zones</filename>:</para>

        <programlisting>#ZONE   TYPE            OPTIONS         IN_OPTIONS              OUT_OPTIONS
fw      firewall        #The firewall itself.
net     ipv4            #Internet
loc     ipv4            #Local wired Zone
dmz     ipv4            #DMZ
vpn     ipv4            #Open VPN clients
wifi    ipv4            #Local Wireless Zone</programlisting>

        <para><filename>/etc/shorewall/policy</filename>:</para>

        <programlisting>#SOURCE         DEST            POLICY          LOGLEVEL        LIMIT
$FW             $FW             ACCEPT
$FW             net             ACCEPT
loc             net             ACCEPT
$FW             vpn             ACCEPT
vpn             net             ACCEPT
vpn             loc             ACCEPT
loc             vpn             ACCEPT
$FW             loc             ACCEPT
loc             $FW             ACCEPT
wifi            all             REJECT          $LOG
net             $FW             DROP            $LOG            1/sec:2
net             loc             DROP            $LOG            2/sec:4
net             dmz             DROP            $LOG            8/sec:30
net             vpn             DROP            $LOG
all             all             REJECT          $LOG</programlisting>

        <para><filename>Note that the firewall&lt;-&gt;local network interface
        is wide open so from a security point of view, the firewall system is
        part of the local zone.</filename></para>

        <para><filename>/etc/shorewall/params (edited)</filename>:</para>

        <programlisting>MIRRORS=&lt;comma-separated list of Shorewall mirrors&gt;

NTPSERVERS=&lt;comma-separated list of NTP servers I sync with&gt;

POPSERVERS=&lt;comma-separated list of server IP addresses&gt;

LOG=info

INT_IF=br0
DMZ_IF=eth3
EXT_IF=eth0
WIFI_IF=eth2
TEST_IF=eth4

OMAK=&lt;IP address at our second home&gt;</programlisting>

        <para><filename>/etc/shorewall/init</filename>:</para>

        <programlisting>echo 1 &gt; /proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_be_liberal</programlisting>

        <para><filename>/etc/shorewall/interfaces</filename> (don't specify
        the BROADCAST addresses if you are using Shorewall-perl):</para>

        <programlisting>#ZONE   INTERFACE       BROADCAST               OPTIONS
net     ${EXT_IF}       detect                  dhcp,logmartians=1,blacklist
dmz     $DMZ_IF         detect                  logmartians=1
loc     $INT_IF         detect                  dhcp,logmartians=1,routeback,bridge
loc     $TEST_IF        detect                  optional
loc     $TEST1_IF       detect                  optional
wifi    $WIFI_IF        detect                  dhcp,maclist,mss=1400
vpn     tun+            -
</programlisting>

        <para><filename>/etc/shorewall/nat</filename>:</para>

        <programlisting>#EXTERNAL               INTERFACE       INTERNAL        ALLINTS         LOCAL
COMMENT One-to-one NAT
206.124.146.178         $EXT_IF:0       192.168.1.3     No              No
206.124.146.180         $EXT_IF:2       192.168.1.6     No              No</programlisting>

        <para><filename>/etc/shorewall/masq (Note the cute trick here and in
        the <filename>following proxyarp</filename> file that allows me to
        access the DSL "Modem" using its default IP address
        (192.168.1.1))</filename>. The leading "+" is required to place the
        rule before the SNAT rules generated by entries in
        <filename>/etc/shorewall/nat</filename> above.</para>

        <programlisting>#INTERFACE              SOURCE          ADDRESS         PROTO   DPORT   IPSEC
COMMENT Handle DSL 'Modem'

+$EXT_IF:192.168.1.1    0.0.0.0/0       192.168.1.254

COMMENT Masquerade VPN clients and Wifi

$EXT_IF                 192.168.2.0/24
$EXT_IF                 192.168.3.0/24

$EXT_IF:192.168.98.1    192.168.99.1    192.168.1.99
$EXT_IF:192.168.99.1    192.168.98.1    192.168.1.98

COMMENT Masquerade Local Network

$EXT_IF                 192.168.1.0/24  206.124.146.179</programlisting>

        <para><filename>/etc/shorewall/proxyarp</filename>:</para>

        <programlisting>#ADDRESS        INTERFACE       EXTERNAL        HAVEROUTE       PERSISTENT
192.168.1.1     $EXT_IF         $INT_IF         yes
206.124.146.177 $DMZ_IF         $EXT_IF         yes
192.168.1.7     $TEST_IF        $INT_IF         yes</programlisting>

        <para><filename>/etc/shorewall/tunnels</filename>:</para>

        <programlisting>#TYPE                   ZONE    GATEWAY         GATEWAY_ZONE
openvpnserver:udp       net     0.0.0.0/0                 #Routed server for RoadWarrior access
openvpnserver:udp       wifi    192.168.3.0/24            #Home wireless network server</programlisting>

        <para><filename>/etc/shorewall/actions</filename>:</para>

        <programlisting>#ACTION
Mirrors             # Accept traffic from Shorewall Mirrors</programlisting>

        <para><filename>/etc/shorewall/action.Mirrors</filename>:</para>

        <programlisting>#TARGET SOURCE          DEST            PROTO   DPORT   SPORT      ORIGDEST     RATE
ACCEPT  $MIRRORS</programlisting>

        <para><filename>/etc/shorewall/rules</filename>:</para>

        <programlisting>SECTION NEW
###############################################################################################################################################################################
#ACTION         SOURCE                          DEST                    PROTO   DPORT                                   SPORT           ORIGDEST        RATE    USER
###############################################################################################################################################################################
REJECT:$LOG     loc                             net                     tcp     25
REJECT:$LOG     loc                             net                     udp     1025:1031
#
# Stop NETBIOS crap
#
REJECT          loc                             net                     tcp     137,445
REJECT          loc                             net                     udp     137:139
#
# Stop my idiotic work laptop from sending to the net with an HP source/dest IP address
#
DROP            loc:!192.168.0.0/22             net
###############################################################################################################################################################################
# Local Network to Firewall
#
REDIRECT-       loc                             3128                    tcp     80                                      -               !192.168.1.1,192.168.0.7,206.124.146.177,155.98.64.80
###############################################################################################################################################################################
# Road Warriors to Firewall
#
ACCEPT            vpn                             fw                      tcp     ssh,time,631,8080
ACCEPT            vpn                             fw                      udp     161,ntp,631
Ping(ACCEPT)      vpn                             fw
###############################################################################################################################################################################
# Road Warriors to DMZ
#
ACCEPT            vpn                             dmz                     udp     domain
ACCEPT            vpn                             dmz                     tcp     www,smtp,smtps,domain,ssh,imap,https,imaps,ftp,10023,pop3       -
Ping(ACCEPT)      vpn                             dmz
###############################################################################################################################################################################
# Local network to DMZ
#
ACCEPT          loc                             dmz                     udp     domain
ACCEPT          loc                             dmz                     tcp     ssh,smtps,www,ftp,imaps,domain,https    -
ACCEPT          loc                             dmz                     tcp     smtp
Trcrt(ACCEPT)   loc                             dmz
###############################################################################################################################################################################
# Internet to ALL -- drop NewNotSyn packets
#
dropNotSyn      net             fw              tcp
#dropNotSyn     net             loc             tcp
dropNotSyn      net             dmz             tcp
###############################################################################################################################################################################
# Internet to DMZ
#
ACCEPT          net                             dmz                     udp     domain
LOG:$LOG        net:64.126.128.0/18             dmz                     tcp     smtp
ACCEPT          net                             dmz                     tcp     smtps,www,ftp,imaps,domain,https        -
ACCEPT          net                             dmz                     tcp     smtp                                    -               206.124.146.177,206.124.146.178
ACCEPT          net                             dmz                     udp     33434:33454
Mirrors         net                             dmz                     tcp     rsync
Limit:$LOG:SSHA,3,60\
                net                             dmz                     tcp     22
Trcrt(ACCEPT)   net                             dmz
##############################################################################################################################################################################
#
# Net to Local
#
# When I'm "on the road", the following two rules allow me VPN access back home using PPTP.
#
DNAT            net                             loc:192.168.1.4         tcp     1729
DNAT            net                             loc:192.168.1.4         gre
#
# Roadwarrior access to Ursa
#
ACCEPT          net:$OMAK                       loc                     tcp     22
Limit:$LOG:SSHA,3,60\
                net                             loc                     tcp     22

#
# ICQ
#
ACCEPT          net                             loc:192.168.1.3         tcp     113,4000:4100
#
# Bittorrent
#
ACCEPT          net                             loc:192.168.1.3         tcp     6881:6889,6969
ACCEPT          net                             loc:192.168.1.3         udp     6881:6889,6969
#
# Real Audio
#
ACCEPT          net                             loc:192.168.1.3         udp     6970:7170
#
# Overnet
#
#ACCEPT         net                             loc:192.168.1.3         tcp     4662
#ACCEPT         net                             loc:192.168.1.3         udp     12112
#
# OpenVPN
#
ACCEPT          net                             loc:192.168.1.3         udp     1194
ACCEPT          net                             loc:192.168.1.6         udp     1194
# Skype
#
ACCEPT          net                             loc:192.168.1.6         tcp     1194
#
# Traceroute
#
Trcrt(ACCEPT)   net                             loc:192.168.1.3
#
# Silently Handle common probes
#
REJECT          net                             loc                     tcp     www,ftp,https
DROP            net                             loc                     icmp    8
###############################################################################################################################################################################
# DMZ to Internet
#
ACCEPT          dmz                             net                     udp     domain,ntp
ACCEPT          dmz                             net                     tcp     echo,ftp,ssh,smtp,whois,domain,www,81,https,cvspserver,2702,2703,8080
ACCEPT          dmz                             net:$POPSERVERS         tcp     pop3
Ping(ACCEPT)    dmz                             net
#
# Some FTP clients seem prone to sending the PORT command split over two packets. This prevents the FTP connection tracking
# code from processing the command  and setting up the proper expectation. The following rule allows active FTP to work in these cases
# but logs the connection so I can keep an eye on this potential security hole.
#
ACCEPT:$LOG     dmz                             net                     tcp     1024:                                   20
###############################################################################################################################################################################
# Local to DMZ
#
ACCEPT          loc                             dmz                     udp     domain,xdmcp
ACCEPT          loc                             dmz                     tcp     www,smtp,smtps,domain,ssh,imap,rsync,https,imaps,ftp,10023,pop3,3128
Trcrt(ACCEPT)   loc                             dmz
###############################################################################################################################################################################
# DMZ to Local
#
ACCEPT          dmz                             loc:192.168.1.5         udp     123
ACCEPT          dmz                             loc:192.168.1.5         tcp     21
Ping(ACCEPT)    dmz                             loc

###############################################################################################################################################################################
# DMZ to Firewall -- ntp &amp; snmp, Silently reject Auth
#
#ACCEPT         net                             loc:192.168.1.3         udp     12112
#
# OpenVPN
#
ACCEPT          net                             loc:192.168.1.3         udp     1194
ACCEPT          net                             loc:192.168.1.6         udp     1194
# Skype
#
ACCEPT          net                             loc:192.168.1.6         tcp     1194
#
# Traceroute
#
Trcrt(ACCEPT)   net                             loc:192.168.1.3
#
# Silently Handle common probes
#
REJECT          net                             loc                     tcp     www,ftp,https
DROP            net                             loc                     icmp    8
###############################################################################################################################################################################
# DMZ to Internet
#
ACCEPT          dmz                             net                     udp     domain,ntp
ACCEPT          dmz                             net                     tcp     echo,ftp,ssh,smtp,whois,domain,www,81,https,cvspserver,2702,2703,8080
ACCEPT          dmz                             net:$POPSERVERS         tcp     pop3
Ping(ACCEPT)    dmz                             net
#
# Some FTP clients seem prone to sending the PORT command split over two packets. This prevents the FTP connection tracking
# code from processing the command  and setting up the proper expectation. The following rule allows active FTP to work in these cases
# but logs the connection so I can keep an eye on this potential security hole.
#
ACCEPT:$LOG     dmz                             net                     tcp     1024:                                   20
###############################################################################################################################################################################
# Local to DMZ
#
ACCEPT          loc                             dmz                     udp     domain,xdmcp
ACCEPT          loc                             dmz                     tcp     www,smtp,smtps,domain,ssh,imap,rsync,https,imaps,ftp,10023,pop3,3128
Trcrt(ACCEPT)   loc                             dmz
###############################################################################################################################################################################
# DMZ to Local
#
ACCEPT          dmz                             loc:192.168.1.5         udp     123
ACCEPT          dmz                             loc:192.168.1.5         tcp     21
Ping(ACCEPT)    dmz                             loc

###############################################################################################################################################################################
# DMZ to Firewall -- ntp &amp; snmp, Silently reject Auth
#
ACCEPT          loc                             dmz                     udp     domain,xdmcp
ACCEPT          loc                             dmz                     tcp     www,smtp,smtps,domain,ssh,imap,rsync,https,imaps,ftp,10023,pop3,3128
Trcrt(ACCEPT)   loc                             dmz
###############################################################################################################################################################################
# DMZ to Local
#
ACCEPT          dmz                             loc:192.168.1.5         udp     123
ACCEPT          dmz                             loc:192.168.1.5         tcp     21
Ping(ACCEPT)    dmz                             loc

###############################################################################################################################################################################
# DMZ to Firewall -- ntp &amp; snmp, Silently reject Auth
#
ACCEPT          dmz                             fw                      tcp     161,ssh
ACCEPT          dmz                             fw                      udp     161,ntp
REJECT          dmz                             fw                      tcp     auth
Ping(ACCEPT)    dmz                             fw
###############################################################################################################################################################################
# Internet to Firewall
#
REJECT          net                             fw                      tcp     www,ftp,https
DROP            net                             fw                      icmp    8
ACCEPT          net                             fw                      udp     33434:33454
ACCEPT          net:$OMAK                       fw                      udp     ntp
ACCEPT          net                             fw                      tcp     auth
ACCEPT          net:$OMAK                       fw                      tcp     22
Limit:$LOG:SSHA,3,60\
                net                             fw                      tcp     22
Trcrt(ACCEPT)   net                             fw
#
# Bittorrent
#
ACCEPT          net                             fw                      tcp     6881:6889,6969
ACCEPT          net                             fw                      udp     6881:6889,6969
###############################################################################################################################################################################
# Firewall to DMZ
#
ACCEPT          fw                              dmz                     tcp     domain,www,ftp,ssh,smtp,https,993,465
ACCEPT          fw                              dmz                     udp     domain
REJECT          fw                              dmz                     udp     137:139
Ping(ACCEPT)    fw                              dmz
##############################################################################################################################################################################
# Avoid logging Freenode.net probes
#
DROP            net:82.96.96.3                          all
</programlisting>

        <para><filename>etc/shorewall/tcdevices</filename></para>

        <programlisting>#INTERFACE      IN_BANDWITH     OUT_BANDWIDTH
$EXT_IF         1300kbit        384kbit
</programlisting>

        <para><filename>/etc/shorewall/tcclasses</filename><programlisting>#INTERFACE      MARK    RATE            CEIL            PRIORITY        OPTIONS
$EXT_IF         10      5*full/10       full            1               tcp-ack,tos-minimize-delay
$EXT_IF         20      3*full/10       9*full/10       2               default
$EXT_IF         30      2*full/10       6*full/10       3</programlisting></para>

        <para><filename>/etc/shorewall/mangle</filename><programlisting>#ACTION           SOURCE          DEST            PROTO   DPORT   SPORT   USER    TEST
CLASSIFY(1:110)   192.168.0.0/22  $EXT_IF                                         #Our internal nets get priority
                                                                                  #over the server
CLASSIFY(1:130)   206.124.146.177 $EXT_IF         tcp     -       873             #Throttle rsync traffic to the
                                                                                  #Shorewall Mirrors.</programlisting></para>
      </blockquote>

      <para>The <filename class="devicefile">tap0</filename> device used by
      the bridged OpenVPN server is created and bridged to <filename
      class="devicefile">eth1</filename> using a SUSE-specific SysV init
      script:</para>

      <blockquote>
        <programlisting>#!/bin/sh
#
#     The Shoreline Firewall (Shorewall) Packet Filtering Firewall - V3.0
#
#     This program is under GPL [http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt]
#
#     (c) 1999,2000,2001,2002,2003,2004,2005 - Tom Eastep (teastep@shorewall.net)
#
#       On most distributions, this file should be called /etc/init.d/shorewall.
#
#       Complete documentation is available at https://shorewall.org
#
#       This program is free software; you can redistribute it and/or modify
#       it under the terms of Version 2 of the GNU General Public License
#       as published by the Free Software Foundation.
#
#       This program is distributed in the hope that it will be useful,
#       but WITHOUT ANY WARRANTY; without even the implied warranty of
#       MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
#       GNU General Public License for more details.
#
#       You should have received a copy of the GNU General Public License
#       along with this program; if not, write to the Free Software
#       Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
#       If an error occurs while starting or restarting the firewall, the
#       firewall is automatically stopped.
#
#       Commands are:
#
#          bridge start                   Starts the bridge
#          bridge restart                 Restarts the bridge
#          bridge reload                  Restarts the bridge
#          bridge stop                    Stops the bridge
#          bridge status                  Displays bridge status
#

# chkconfig: 2345 4 99
# description: Packet filtering firewall

### BEGIN INIT INFO
# Provides:       bridge
# Required-Start: boot.udev
# Required-Stop:
# Default-Start:  2 3 5
# Default-Stop:   0 1 6
# Description:    starts and stops the bridge
### END INIT INFO

################################################################################
# Interfaces to be bridged -- may be listed by device name or by MAC
#
INTERFACES="eth1"

#
# Tap Devices
#
TAPS="tap0"

################################################################################
# Give Usage Information                                                       #
################################################################################
usage() {
    echo "Usage: $0 start|stop|reload|restart|status"
    exit 1
}
#################################################################################
# Find the interface with the passed MAC address
#################################################################################
find_interface_by_mac() {
    local mac
    mac=$1
    local first
    local second
    local rest
    local dev

    /sbin/ip link ls | while read first second rest; do
        case $first in
            *:)
                dev=$second
                ;;
            *)
                if [ "$second" = $mac ]; then
                    echo ${dev%:}
                    return
                fi
        esac
    done
}
################################################################################
# Convert MAC addresses to interface names
################################################################################
get_interfaces() {
    local interfaces
    interfaces=
    local interface

    for interface in $INTERFACES; do
        case $interface in
            *:*:*)
                interface=$(find_interface_by_mac $interface)
                [ -n "$interface" ] || echo "WARNING: Can't find an interface with MAC address $mac"
                ;;
        esac
        interfaces="$interfaces $interface"
    done

    INTERFACES="$interfaces"
}
################################################################################
# Start the Bridge
################################################################################
do_start()
{
    local interface

    get_interfaces

    for interface in $TAPS; do
        /usr/sbin/openvpn --mktun --dev $interface
    done

   /sbin/brctl addbr br0

   for interface in $INTERFACES $TAPS; do
        /sbin/ip link set $interface up
        /sbin/brctl addif br0 $interface
   done
}
################################################################################
# Stop the Bridge
################################################################################
do_stop()
{
    local interface

    get_interfaces

    for interface in $INTERFACES $TAPS; do
        /sbin/brctl delif br0 $interface
        /sbin/ip link set $interface down
    done

    /sbin/ip link set br0 down

    /sbin/brctl delbr br0

    for interface in $TAPS; do
        /usr/sbin/openvpn --rmtun --dev $interface
    done
}
################################################################################
# E X E C U T I O N    B E G I N S   H E R E                                   #
################################################################################
command="$1"

case "$command" in
    start)
        do_start
        ;;
    stop)
        do_stop
        ;;
    restart|reload)
        do_stop
        do_start
        ;;
    status)
        /sbin/brctl show
        ;;
    *)
        usage
        ;;
esac
</programlisting>
      </blockquote>
    </section>
  </section>
</article>