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shorewall_code/Shorewall/manpages/shorewall-hosts.xml
Tom Eastep acb2e2a8ab Implement mss= in hosts file.
Signed-off-by: Tom Eastep <teastep@shorewall.net>
2012-03-12 15:14:35 -07:00

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
"http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
<refentry>
<refmeta>
<refentrytitle>shorewall-hosts</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>hosts</refname>
<refpurpose>Shorewall file</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>/etc/shorewall/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="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="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="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="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="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="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="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="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="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="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>
</refsect1>
<refsect1>
<title>See ALSO</title>
<para><ulink
url="http://shorewall.net/configuration_file_basics.htm#Pairs">http://shorewall.net/configuration_file_basics.htm#Pairs</ulink></para>
<para>shorewall(8), shorewall-accounting(5), shorewall-actions(5),
shorewall-blacklist(5), shorewall_interfaces(5), shorewall-ipsets(5),
shorewall-maclist(5), shorewall-masq(5), shorewall-nat(5),
shorewall-nesting(5), shorewall-netmap(5), shorewall-params(5),
shorewall-policy(5), shorewall-providers(5), shorewall-proxyarp(5),
shorewall-rtrules(5), shorewall-routestopped(5), shorewall-rules(5),
shorewall.conf(5), shorewall-secmarks(5), shorewall-tcclasses(5),
shorewall-tcdevices(5), shorewall-tcrules(5), shorewall-tos(5),
shorewall-tunnels(5), shorewall-zones(5)</para>
</refsect1>
</refentry>