Add caution about macros and non-standard ports.

Signed-off-by: Tom Eastep <teastep@shorewall.net>

docs/standalone.xml

@@ -536,6 +536,12 @@ Web(ACCEPT) net       $FW
 IMAP(ACCEPT)net       $FW</programlisting>
     </example>
 
+    <caution>
+      <para>The Shorewall-provided macros assume that the associated service
+      is using it's standard port and will not work with services listening on
+      a non-standard port.</para>
+    </caution>
+
     <para>You may also choose to code your rules directly without using the
     pre-defined macros. This will be necessary in the event that there is not
     a pre-defined macro that meets your requirements. In that case the general

docs/three-interface.xml

@@ -971,6 +971,12 @@ ACCEPT    dmz       $FW                 udp        53              </programlist
     code the appropriate rules directly. <ulink url="ports.html">This
     page</ulink> can be of help if you don't know the protocol and port
     involved.</para>
+
+    <caution>
+      <para>The Shorewall-provided macros assume that the service is using its
+      standard port and will not work with a service listening on a
+      non-standard port.</para>
+    </caution>
   </section>
 
   <section id="Open">

docs/two-interface.xml

@@ -807,6 +807,12 @@ FTP(DNAT)  net       loc:10.10.10.1</programlisting> For
         url="FTP.html">Shorewall FTP documentation</ulink> for more
         information.</para>
       </example> A couple of important points to keep in mind: <itemizedlist>
+        <listitem>
+          <para>The Shorewall-provided macros assume that the service is using
+          its standard port and will not work with a service listening on a
+          non-standard port.</para>
+        </listitem>
+
         <listitem>
           <para>You must test the above rule from a client outside of your
           local network (i.e., don't test from a browser running on computers