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<!-- Module User's Guide -->

<chapter>
	
	<title>&adminguide;</title>
	
	<section>
	<title>Overview</title>
	<para>
	This module implements SIP authentication and authorization with
	DIAMETER server, namely DIameter Server Client (DISC).
	</para>
	<para>
	NOTE: diameter support was developed for DISC (DIameter Server Client 
	project at http://developer.berlios.de/projects/disc/). This project 
	seems to be no longer maintained and DIAMETER specifications were updated
	in the meantime. Thus, the module is obsolete and needs rework to be 
	usable with opendiameter or other DIAMETER servers.
	</para>
	<para>
	The digest authentication mechanism is presented in next figure.
	</para>
	<example>
	<title>Digest Authentication</title>
	<programlisting format="linespecific">
...
	a) First phase of Digest Authentication for SIP:


     +----+ SIP INVITE   +=====+  DIAMETER      +------+       +------+
     |    | no Auth hdr  #/////#  AA-Request    |      |       |      |
     |    |---------1---&gt;#/////#-------2-------&gt;|      |---2--&gt;|      |
     |UAC |              #UAS//#                |DClnt |       |DSrv  |
     |    |&lt;-----4-------#(SER)#&lt;------3--------|(DISC)|&lt;--3---|(DISC)|
     |    |     401      #/////#  DIAMETER      |      |       |      |
     +----+ Unauthorized +=====+  AA-Answer     +------+       +------+
                                  Result-Code=4001


	b) Second phase of Digest Authentication for SIP:


     +----+ SIP INVITE   +=====+  DIAMETER     +------+       +----+
     |    | Auth hdr     #/////#  AA-Request   |      |       |    |
     |    |--------1----&gt;#/////#-------2------&gt;|      |---2--&gt;|    |
     |UAC |              #UAS//#               |DClnt |       |DSrv|
     |    |&lt;-------4-----#(SER)#&lt;------3-------|      |&lt;--3---|    |
     |    |      200 OK  #/////#  DIAMETER     |      |       |    |
     +----+              +=====+  AA-Answer    +------+       +----+
                                  Result-Code=2001

...
</programlisting>
	</example>
	</section>

	<section>
	<title>Dependencies</title>
	<section>
		<title>&kamailio; Modules</title>
		<para>
		The following modules must be loaded before this module:
			<itemizedlist>
			<listitem>
			<para>
				<emphasis>sl</emphasis> - used to send stateless replies.
			</para>
			</listitem>
			</itemizedlist>
		</para>
	</section>
	<section>
		<title>External Libraries or Applications</title>
		<para>
		The following libraries or applications must be installed before running
		&kamailio; with this module loaded:
			<itemizedlist>
			<listitem>
			<para>
				<emphasis>None</emphasis>.
			</para>
			</listitem>
			</itemizedlist>
		</para>
	</section>
	</section>

	<section>
	<title>Exported Parameters</title>
	<section>
		<title><varname>diameter_client_host</varname> (string)</title>
		<para>
		Hostname of the machine where the DIAMETER Client is running.
		</para>
		<para>
		<emphasis>
			Default value is <quote>localhost</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>diameter_client_host</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("auth_diameter", "diameter_client_host", "10.10.10.10")
...
</programlisting>
		</example>
	</section>
	<section>
		<title><varname>diameter_client_port</varname> (int)</title>
		<para>
		Port number where the DIAMETER Client is listening.
		</para>
		<para>
		<emphasis>
			Default value is <quote>3000</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>diameter_client_port</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("auth_diameter", "diameter_client_port", 3000)
...
</programlisting>
		</example>
	</section>
	<section>
		<title><varname>use_domain</varname> (int)</title>
		<para>
		Specifies whether the domain name part of URI is used when checking the
		user's privileges.
		</para>
		<para>
		<emphasis>
			Default value is <quote>0 (0==false and 1==true )</quote>.
		</emphasis>
		</para>
		<example>
		<title>Set <varname>use_domain</varname> parameter</title>
		<programlisting format="linespecific">
...
modparam("auth_diameter", "use_domain", 1)
...
</programlisting>
		</example>
	</section>
	</section>
	<section>
	<title>Exported Functions</title>
	<section>
		<title>
		<function moreinfo="none">diameter_www_authorize(realm)</function>
		</title>
		<para>
		SIP Server checks for authorization having a DIAMETER server in backend.
		If no credentials are provided inside the SIP request then a challenge
		is sent back to UAC. If the credentials don't match the ones computed by
		DISC then <quote>403 Forbidden</quote> is sent back.
		</para>
		<para>Negative codes may be interpreted as follows:</para>
		<itemizedlist>
			<listitem><para>
			<emphasis>-5 (generic error)</emphasis> - some generic error
			occurred and no reply was sent out;
			</para></listitem>
			<listitem><para>
			<emphasis>-3 (stale nonce)</emphasis> - stale nonce;
			</para></listitem>
		</itemizedlist>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para><emphasis>realm</emphasis> - the realm to be use for
			authentication and authorization. The string may contain 
			pseudo variables.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function>diameter_www_authorize</function> usage</title>
		<programlisting format="linespecific">
...
if(!diameter_www_authorize("siphub.net"))
{ /* user is not authorized */
	exit;
};
...
</programlisting>
		</example>
	</section>
	<section>
		<title>
		<function moreinfo="none">diameter_proxy_authorize(realm)</function>
		</title>
		<para>
		SIP Proxy checks for authorization having a DIAMETER server in backend.
		If no credentials are provided inside the SIP request then a challenge
		is sent back to UAC. If the credentials don't match the ones computed by
		DISC then <quote>403 Forbidden</quote> is sent back.  For more about 
		the negative return codes, see the above function.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para><emphasis>realm</emphasis> - the realm to be use for
			authentication and authorization. The string may contain 
			pseudo variables.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function>diameter_proxy_authorize</function> usage</title>
		<programlisting format="linespecific">
...
if(!diameter_proxy_authorize("siphub.net"))
{ /* user is not authorized */
	exit;
};
...
</programlisting>
		</example>
	</section>
	<section>
		<title>
		<function moreinfo="none">diameter_is_user_in(who, group)</function>
		</title>
		<para>
		The method performs group membership checking with DISC.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para><emphasis>who</emphasis> - what header to be used to get the
			SIP URI that is wanted to be checked being member in a certain group.
			It can be: <quote>Request-URI</quote>, <quote>From</quote>,
			<quote>To</quote> or <quote>Credentials</quote>.
			</para>
		</listitem>
		<listitem>
			<para><emphasis>group</emphasis> - the group name where to check if
			the user is part of.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function>diameter_is_user_in</function> usage</title>
		<programlisting format="linespecific">
...
if(!diameter_is_user_in("From", "voicemail"))
{ /* user is not authorized */
	exit;
};
...
</programlisting>
		</example>
	</section>
	</section>
	<section>
	<title>Installation and Running</title>
	<para>Notes about installation and running.</para>
	</section>
</chapter>