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<chapter>
	
	<title>&adminguide;</title>
	
	<section>
	<title>Overview</title>
	<para>
		This module contains functions that are used to perform authentication 
		using a Radius server. Basically the proxy will pass along the 
		credentials to the radius server which will in turn send a reply 
		containing result of the authentication. So basically the whole
		authentication is done in the Radius server. Before sending the request 
		to the radius server we perform some sanity checks over the 
		credentials to make sure that only well formed credentials will get to 
		the server. We have implemented radius authentication according to 
		draft-sterman-aaa-sip-00. This module requires the radiusclient-ng
		library version 0.5.0 or higheer or freeradius-client which is available from 
		<ulink url='https://github.com/FreeRADIUS/freeradius-client/'>
		https://github.com/FreeRADIUS/freeradius-client/</ulink>.
		You can also install this library from distribution repositories.
	</para>
	</section>
	<section>
	<title>Additional Credentials</title>
	<para>
		When performing authentification, the RADIUS server may include additional
		credentials in the response. This scheme is very useful in fetching
		additional user information from the RADIUS server without making
		extra queries.
	</para>
	<para>
		The additional credentials are embedded in the RADIUS reply as AVPs 
		<quote>SIP-AVP</quote>. The syntax of the value is:
		<itemizedlist>
			<listitem><para><emphasis>
			value = SIP_AVP_NAME SIP_AVP_VALUE
			</emphasis></para></listitem>
			<listitem><para><emphasis>
			SIP_AVP_NAME = STRING_NAME | '#'ID_NUMBER
			</emphasis></para></listitem>
			<listitem><para><emphasis>
			SIP_AVP_VALUE = ':'STRING_VALUE | '#'NUMBER_VALUE
			</emphasis></para></listitem>
		</itemizedlist>
	</para>
	<para>
		All additional credentials will be stored as &kamailio; AVPs
		(SIP_AVP_NAME = SIP_AVP_VALUE).
	</para>
	<para>
		The RPID value may be fetch via this mechanism.
	</para>
	<example>
	<title><quote>SIP-AVP</quote> RADIUS AVP exmaples</title>
		<programlisting format="linespecific">
....
"email:joe@yahoo.com"
    - STRING NAME AVP (email) with STRING VALUE (joe@yahoo.com)
"#14:joe@yahoo.com"
    - ID AVP (14) with STRING VALUE (joe@yahoo.com)
"age#28"
    - STRING NAME AVP (age) with INTEGER VALUE (28)
"#14#28"
    - ID AVP (14) with INTEGER VALUE (28)
....
		</programlisting>
	</example>
	</section>

	<section>
	<title>Dependencies</title>
		<section>
			<title>Modules</title>
			<para>
			The module depends on the following modules (in the other words 
			the listed modules must be loaded before this module):
			<itemizedlist>
				<listitem>
				<para><emphasis>auth</emphasis>
				-- Generic authentication functions
				</para>
				</listitem>
			</itemizedlist>
			</para>
		</section>
		<section>
			<title>External Libraries or Applications</title>
			<para>
			The following libraries or applications must be installed 
			before compilling &kamailio; with this module loaded:
			</para>
			<itemizedlist>
				<para>One of these libraries. Notice that development of
				radiusclient-ng has stopped, as the project merged with
				freeradius-client.</para>
				<listitem>
				<para>
				<emphasis>freeradius-client</emphasis>  available from 
				<ulink url='https://github.com/FreeRADIUS/freeradius-client/'>
				https://github.com/FreeRADIUS/freeradius-client/</ulink>.
				</para>
				</listitem>
				<listitem>
				<para><emphasis>radiusclient-ng</emphasis> 0.5.0 or higher -- 
				library and development files. See <ulink 
				url='http://developer.berlios.de/projects/radiusclient-ng/'>
				http://developer.berlios.de/projects/radiusclient-ng/</ulink>.
				</para>
				</listitem>
			</itemizedlist>
		</section>
	</section>

	<section>
	<title>Parameters</title>
	<section>
		<title><varname>radius_config</varname> (string)</title>
		<para>
		This is the location of the configuration file of radius client 
		libraries.
		</para>
		<para>
		Default value is 
			<quote>/usr/local/etc/radiusclient-ng/radiusclient.conf</quote>.
		</para>
		<example>
		<title><varname>radius_config</varname> parameter usage</title>
		<programlisting format="linespecific">
modparam("auth_radius", "radius_config", "/etc/radiusclient.conf")
		</programlisting>
		</example>
	</section>
	<section>
		<title><varname>service_type</varname> (integer)</title>
		<para>
		This is the value of the Service-Type radius attribute to be used. 
		The default should be fine for most people. See your radius client 
		include files for numbers to be put in this parameter if you need 
		to change it.
		</para>
		<para>
		Default value is <quote>15</quote>.
		</para>
		<example>
		<title><varname>service_type</varname> parameter usage</title>
		<programlisting format="linespecific">
modparam("auth_radius", "service_type", 15)
		</programlisting>
		</example>
	</section>
	<section>
		<title><varname>auth_extra</varname> (string)</title>
		<para>
		Semi-colon separated list of extra RADIUS attribute
		name=pseudo variable pairs. When radius_www_authorize() or
		radius_proxy_authorize() function is called, listed extra
		attributes are included in RADIUS request with 
		current values of corresponding pseudo variables.
		</para>
		<para>
		There is no default value, i.e., by default no extra
		attributes are included.
		</para>
		<example>
		<title><varname>auth_extra</varname> parameter usage</title>
		<programlisting format="linespecific">
modparam("auth_radius", "auth_extra", "Acct-Session-Id=$ci")
		</programlisting>
		</example>
	</section>
        <section>
                <title><varname>use_ruri_flag</varname> (integer)</title>
                <para>
                When this parameter is set to the value other than "-1" and the
                request being authenticated has flag with matching number set
                via setflag() function, use Request URI instead of uri parameter
                value from the Authorization / Proxy-Authorization header field
                to perform RADIUS authentication.  This is intended to provide
                workaround for misbehaving NAT / routers / ALGs that alter request
                in the transit, breaking authentication.  At the time of this
                writing, certain versions of Linksys WRT54GL are known to do that.
                </para>
                <para>
                Default value is <quote>-1</quote>.
                </para>
                <example>
                <title><varname>use_ruri_flag</varname> parameter usage</title>
                <programlisting format="linespecific">
modparam("auth_radius", "use_ruri_flag", 22)
                </programlisting>
                </example>
        </section>
	<section id="auth_radius.p.radius_avps_mode">
		<title><varname>radius_avps_mode</varname> (integer)</title>
		<para>
			If set to 1, all RADIUS AVPs returned by RADIUS server are stored
			in &kamailio; AVPs list. If set to 0, only the SIP_AVP type of RADIUS
			AVPs are stored in &kamailio; AVPs list.
		</para>
		<para>
			Default value is 0.
		</para>
		<example>
		<title><varname>radius_avps_mode</varname> parameter usage</title>
		<programlisting format="linespecific">
modparam("auth_radius", "radius_avps_mode", 1)
		</programlisting>
		</example>
	</section>
	<section id="auth_radius.p.append_realm_to_username">
		<title><varname>append_realm_to_username</varname> (integer)</title>
		<para>
			If set to 1, the username passed to the RADIUS server will have the
			digest realm appended to it, if no domain is provided in the digest
			username.
		</para>
		<para>
			Default value is 1.
		</para>
		<example>
		<title><varname>append_realm_to_username</varname> parameter usage</title>
		<programlisting format="linespecific">
modparam("auth_radius", "append_realm_to_username", 0)
		</programlisting>
		</example>
	</section>
	</section>

	<section>
	<title>Functions</title>
	<section>
		<title><function moreinfo="none">radius_www_authorize(realm [, uri_user])</function></title>
		<para>
		The function verifies credentials according to 
		<ulink url="http://www.ietf.org/rfc/rfc2617.txt">RFC2617</ulink>. If 
		the credentials are verified successfully then the function will 
		succeed and mark the credentials as authorized (marked credentials can 
		be later used by some other functions).
		</para>
		<para>
		If the function	was unable to  
		verify the credentials for some reason, it fails and
		assigns a WWW-Authorize header containing a new
	challenge to digest_challenge AVP (see modules/auth).
	The script should
	then respond with 401 that includes this header, which will
	challenge the user again.
		</para>
		<para>Negative result codes may be interpreted as follows:</para>
		<itemizedlist>
			<listitem><para>
			<emphasis>-7 (internal error)</emphasis> - some
			internal error occurred (see syslog);
			</para></listitem>
			<listitem><para>
			<emphasis>-6 (nonce reused)</emphasis> - nonce is used more than once;
			</para></listitem>
			<listitem><para>
			<emphasis>-5 (no credentials)</emphasis> - credentials were not found in request;
			</para></listitem>
			<listitem><para>
			<emphasis>-4 (stale nonce)</emphasis> - stale nonce;
			</para></listitem>
			<listitem><para>
			<emphasis>-2 (authorization failed)</emphasis> - RADIUS responded with Access Reject which may be, for example, due to user not found or wrong password;
			</para></listitem>
			<listitem><para>
			<emphasis>-1 (error)</emphasis> - some error occured during authorization (see syslog);
			</para></listitem>
		</itemizedlist>
		<para>
		This function will perform sanity checks over
	the received  
		credentials and then pass them along to RADIUS
	server which will  
		verify the credentials and return whether they are valid or not.
		</para>
		<para>Meaning of the parameter is as follows:</para>
		<itemizedlist>
		<listitem>
			<para><emphasis>realm</emphasis> - Realm is a
	opaque string that  
			the user agent should present to the user so he
	can decide what  
			username and password to use.  In case of
	REGISTER requests it is usually hostpart of To URI.
			</para>
			<para>
			The string may contain pseudo variables.
			</para>
		</listitem>
		<listitem>
			<para><emphasis>uri_user</emphasis> - Uri_user is an
			optional pseudo variable parameter whose value, if
			present, will be given to Radius server as value of
			SIP-URI-User check item.
			If uri_user pseudo variable parameter is not
			present, the server will generate 
                        SIP-URI-User check item value from user part of
			To/From URI.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function moreinfo="none">radius_www_authorize</function> usage</title>
		<programlisting format="linespecific">
...
    if (!radius_www_authorize("$td")) {
        switch ($rc) {
        case -7:
	    send_reply("500", "Server Internal Error");
	    exit;
        case -1:
	    send_reply("400", "Bad Request");
	    exit;
        default:
        };
        if (defined($avp(digest_challenge)) &amp;&amp;
                ($avp(digest_challenge) != "")) {
            append_to_reply("$avp(digest_challenge)");
        };
        send_reply("401", "Unauthorized");
        exit;
    };
...
</programlisting>
		</example>
	</section>

	<section>
		<title><function
		moreinfo="none">radius_proxy_authorize(realm [, uri_user])</function></title>
		<para>
		The function verifies credentials according to 
		<ulink url="http://www.ietf.org/rfc/rfc2617.txt">RFC2617</ulink>. If 
		the credentials are verified successfully then the function will 
		succeed and mark the credentials as authorized (marked credentials can 
		be later used by some other functions).  
		</para>
		<para>If the function was unable to  
		verify the credentials for some reason, it fails and
		assigns a Proxy-Authorize header containing a new
	challenge to digest_challenge AVP.  The script should
	then respond with 407 that includes this header, which will
	challenge the user again.
		For negative result codes, see the above function.
		</para>
		<para>
		This function will perform sanity checks over the received 
		credentials and then pass them along to RADIUS server which will 
		verify the credentials and return whether they are valid or not.
		</para>
		<para>Meaning of the parameters is as follows:</para>
		<itemizedlist>
		<listitem>
			<para><emphasis>realm</emphasis> - Realm is a opaque string that 
			the user agent should present to the user so he can decide what 
			username and password to use.  In case of
	non-REGISTER requests it is usually hostpart of From or
		P-Preferred-Identity URI.
			</para>
			<para>
			The string may contain pseudo variables.
			</para>
		</listitem>
		<listitem>
			<para><emphasis>uri_user</emphasis> - Uri_user is an
			optional pseudo variable parameter whose value, if
			present, will be given to Radius server as value of
			SIP-URI-User check item.
			If uri_user pseudo variable parameter is not
			present, the server will generate 
                        SIP-URI-User check item value from user part of
			To/From URI.
			</para>
		</listitem>
		</itemizedlist>
		<para>
		This function can be used from REQUEST_ROUTE.
		</para>
		<example>
		<title><function moreinfo="none">proxy_authorize</function> usage</title>
		<programlisting format="linespecific">
...
    if (!radius_proxy_authorize("$pd", "$pU")) { # Realm and URI user are taken
        switch ($rc) {                           # from P-Preferred-Identity
        case -7:                                 # header field
	    send_reply("500", "Server Internal Error");
	    exit;
        case -1:
	    send_reply("400", "Bad Request");
	    exit;
        default:
        };
        if (defined($avp(digest_challenge)) &amp;&amp;
                ($avp(digest_challenge) != "")) {
            append_to_reply("$avp(digest_challenge)");
        };
        send_reply("407", "Proxy Authentication Required");
        exit;
    };
...
</programlisting>
		</example>
	</section>
	</section>
</chapter>
