shorewall_code/Shorewall/manpages/shorewall-hosts.xml

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<refentry>
  <refmeta>
    <refentrytitle>shorewall-hosts</refentrytitle>

    <manvolnum>5</manvolnum>

    <refmiscinfo>Configuration Files</refmiscinfo>
  </refmeta>

  <refnamediv>
    <refname>hosts</refname>

    <refpurpose>Shorewall file</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>/etc/shorewall[6]/hosts</command>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para>This file is used to define zones in terms of subnets and/or
    individual IP addresses. Most simple setups don't need to (should not)
    place anything in this file.</para>

    <para>The order of entries in this file is not significant in determining
    zone composition. Rather, the order that the zones are declared in <ulink
    url="/manpages/shorewall-zones.html">shorewall-zones</ulink>(5) determines
    the order in which the records in this file are interpreted.</para>

    <warning>
      <para>The only time that you need this file is when you have more than
      one zone connected through a single interface.</para>
    </warning>

    <warning>
      <para>If you have an entry for a zone and interface in <ulink
      url="/manpages/shorewall-interfaces.html">shorewall-interfaces</ulink>(5)
      then do not include any entries in this file for that same (zone,
      interface) pair.</para>
    </warning>

    <para>The columns in the file are as follows.</para>

    <variablelist>
      <varlistentry>
        <term><emphasis role="bold">ZONE</emphasis> -
        <emphasis>zone-name</emphasis></term>

        <listitem>
          <para>The name of a zone declared in <ulink
          url="/manpages/shorewall-zones.html">shorewall-zones</ulink>(5). You
          may not list the firewall zone in this column.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">HOST(S)</emphasis> -
        <emphasis>interface</emphasis>:{[{<emphasis>address-or-range</emphasis>[<emphasis
        role="bold">,</emphasis><emphasis>address-or-range</emphasis>]...|<emphasis
        role="bold">+</emphasis><emphasis>ipset</emphasis>|<emphasis
        role="bold">dynamic</emphasis>}[<emphasis>exclusion</emphasis>]</term>

        <listitem>
          <para>The name of an interface defined in the <ulink
          url="/manpages/shorewall-interfaces.html">shorewall-interfaces</ulink>(5)
          file followed by a colon (":") and a comma-separated list whose
          elements are either:</para>

          <orderedlist numeration="loweralpha">
            <listitem>
              <para>The IP <replaceable>address</replaceable> of a
              host.</para>
            </listitem>

            <listitem>
              <para>A network in CIDR format.</para>
            </listitem>

            <listitem>
              <para>An IP address range of the form
              <emphasis>low.address</emphasis>-<emphasis>high.address</emphasis>.
              Your kernel and iptables must have iprange match support.</para>
            </listitem>

            <listitem>
              <para>The name of an <emphasis>ipset</emphasis>.</para>
            </listitem>

            <listitem>
              <para>The word <option>dynamic</option> which makes the zone
              dynamic in that you can use the <command>shorewall add</command>
              and <command>shorewall delete</command> commands to change to
              composition of the zone.</para>
            </listitem>
          </orderedlist>

          <blockquote>
            <para>You may also exclude certain hosts through use of an
            <emphasis>exclusion</emphasis> (see <ulink
            url="/manpages/shorewall-exclusion.html">shorewall-exclusion</ulink>(5).</para>
          </blockquote>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><emphasis role="bold">OPTIONS</emphasis> (Optional) -
        [<emphasis>option</emphasis>[<emphasis
        role="bold">,</emphasis><emphasis>option</emphasis>]...]</term>

        <listitem>
          <para>A comma-separated list of options from the following list. The
          order in which you list the options is not significant but the list
          must have no embedded white-space.</para>

          <variablelist>
            <varlistentry>
              <term><emphasis role="bold">blacklist</emphasis></term>

              <listitem>
                <para>Check packets arriving on this port against the <ulink
                url="/manpages/shorewall-blacklist.html">shorewall-blacklist</ulink>(5)
                file.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">broadcast</emphasis></term>

              <listitem>
                <para>Used when you want to include limited broadcasts
                (destination IP address 255.255.255.255) from the firewall to
                this zone. Only necessary when:</para>

                <orderedlist>
                  <listitem>
                    <para>The network specified in the HOST(S) column does not
                    include 255.255.255.255.</para>
                  </listitem>

                  <listitem>
                    <para>The zone does not have an entry for this interface
                    in <ulink
                    url="/manpages/shorewall-interfaces.html">shorewall-interfaces</ulink>(5).</para>
                  </listitem>
                </orderedlist>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">destonly</emphasis></term>

              <listitem>
                <para>Normally used with the Multi-cast IP address range
                (224.0.0.0/4). Specifies that traffic will be sent to the
                specified net(s) but that no traffic will be received from the
                net(s).</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">ipsec</emphasis></term>

              <listitem>
                <para>The zone is accessed via a kernel 2.6 ipsec SA. Note
                that if the zone named in the ZONE column is specified as an
                IPSEC zone in the <ulink
                url="/manpages/shorewall-zones.html">shorewall-zones</ulink>(5)
                file then you do NOT need to specify the 'ipsec' option
                here.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">maclist</emphasis></term>

              <listitem>
                <para>Connection requests from these hosts are compared
                against the contents of <ulink
                url="/manpages/shorewall-maclist.html">shorewall-maclist</ulink>(5).
                If this option is specified, the interface must be an Ethernet
                NIC or equivalent and must be up before Shorewall is
                started.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis
              role="bold">mss</emphasis>=<replaceable>mss</replaceable></term>

              <listitem>
                <para>Added in Shorewall 4.5.2. When present, causes the TCP
                mss for new connections to/from the hosts given in the HOST(S)
                column to be clamped at the specified
                <replaceable>mss</replaceable>.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">nosmurfs</emphasis></term>

              <listitem>
                <para>This option only makes sense for ports on a
                bridge.</para>

                <para>Filter packets for smurfs (packets with a broadcast
                address as the source).</para>

                <para>Smurfs will be optionally logged based on the setting of
                SMURF_LOG_LEVEL in <ulink
                url="/manpages/shorewall.conf.html">shorewall.conf</ulink>(5).
                After logging, the packets are dropped.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">routeback</emphasis></term>

              <listitem>
                <para>Shorewall should set up the infrastructure to pass
                packets from this/these address(es) back to themselves. This
                is necessary if hosts in this group use the services of a
                transparent proxy that is a member of the group or if DNAT is
                used to send requests originating from this group to a server
                in the group.</para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><emphasis role="bold">tcpflags</emphasis></term>

              <listitem>
                <para>Packets arriving from these hosts are checked for
                certain illegal combinations of TCP flags. Packets found to
                have such a combination of flags are handled according to the
                setting of TCP_FLAGS_DISPOSITION after having been logged
                according to the setting of TCP_FLAGS_LOG_LEVEL.</para>
              </listitem>
            </varlistentry>
          </variablelist>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Examples</title>

    <variablelist>
      <varlistentry>
        <term>Example 1</term>

        <listitem>
          <para>The firewall runs a PPTP server which creates a ppp interface
          for each remote client. The clients are assigned IP addresses in the
          network 192.168.3.0/24 and in a zone named 'vpn'.<programlisting>#ZONE       HOST(S)               OPTIONS
vpn         ppp+:192.168.3.0/24</programlisting></para>
        </listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>FILES</title>

    <para>/etc/shorewall/hosts</para>

    <para>/etc/shorewall6/hosts</para>
  </refsect1>

  <refsect1>
    <title>See ALSO</title>

    <para><ulink
    url="/configuration_file_basics.htm#Pairs">http://www.shorewall.net/configuration_file_basics.htm#Pairs</ulink></para>

    <para>shorewall(8)</para>
  </refsect1>
</refentry>