
Auth Module

Jan Janak

   FhG Fokus

Juha Heinanen

   Song Networks

Bogdan-Andrei Iancu

   voice-system.ro

Edited by

Jan Janak

   Copyright © 2002, 2003 FhG FOKUS

   Copyright © 2005 voice-system.ro
     _________________________________________________________

   Table of Contents
   1. User's Guide

        1.1. Overview
        1.2. Dependencies

              1.2.1. OpenSER Modules
              1.2.2. External Libraries or Applications

        1.3. Exported Parameters

              1.3.1. secret (string)
              1.3.2. nonce_expire (integer)
              1.3.3. rpid_prefix (string)
              1.3.4. rpid_suffix (string)
              1.3.5. realm_prefix (string)
              1.3.6. rpid_avp (string)

        1.4. Exported Functions

              1.4.1. www_challenge(realm, qop)
              1.4.2. proxy_challenge(realm, qop)
              1.4.3. consume_credentials()
              1.4.4. is_rpid_user_e164()
              1.4.5. append_rpid_hf()
              1.4.6. append_rpid_hf(prefix, suffix)

   2. Developer's Guide
   3. Frequently Asked Questions

   List of Examples
   1-1. secret parameter example
   1-2. nonce_expire parameter example
   1-3. rpid_prefix parameter example
   1-4. rpid_suffix parameter example
   1-5. realm_prefix parameter example
   1-6. rpid_avp parameter example
   1-7. www_challenge usage
   1-8. proxy_challenge usage
   1-9. consume_credentials example
   1-10. is_rpid_user_e164 usage
   1-11. append_rpid_hf usage
   1-12. append_rpid_hf(prefix, suffix) usage
     _________________________________________________________

Chapter 1. User's Guide

1.1. Overview

   This is a generic module that itself doesn't provide all
   functions necessary for authentication but provides functions
   that are needed by all other authentication related modules
   (so called authentication backends).

   We decided to break the authentication code into several
   modules because there are now more than one backends
   (currently database authentication and radius are supported).
   This allows us to create separate packages so uses can install
   and load only required functionality. This also allows us to
   avoid unnecessary dependencies in the binary packages.
     _________________________________________________________

1.2. Dependencies

1.2.1. OpenSER Modules

   The module depends on the following modules (in the other
   words the listed modules must be loaded before this module):

     * sl -- Stateless replies
     _________________________________________________________

1.2.2. External Libraries or Applications

   The following libraries or applications must be installed
   before running OpenSER with this module loaded:

     * none
     _________________________________________________________

1.3. Exported Parameters

1.3.1. secret (string)

   Secret phrase.

   Default value is randomly generated string.

   Example 1-1. secret parameter example
modparam("auth", "secret", "johndoessecretphrase")
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1.3.2. nonce_expire (integer)

   Nonces have limited lifetime. After a given period of time
   nonces will be considered invalid. This is to protect replay
   attacks. Credentials containing a stale nonce will be not
   authorized, but the user agent will be challenged again. This
   time the challenge will contain stale parameter which will
   indicate to the client that it doesn't have to disturb user by
   asking for username and password, it can recalculate
   credentials using existing username and password.

   The value is in seconds and default value is 300 seconds.

   Example 1-2. nonce_expire parameter example
modparam("auth", "nonce_expire", 600)   # Set nonce_expire to 600s
     _________________________________________________________

1.3.3. rpid_prefix (string)

   Prefix to be added to Remote-Party-ID header field just before
   the URI returned from either radius or database.

   Default value is "".

   Example 1-3. rpid_prefix parameter example
modparam("auth", "rpid_prefix", "Whatever <")
     _________________________________________________________

1.3.4. rpid_suffix (string)

   Suffix to be added to Remote-Party-ID header field after the
   URI returned from either radius or database.

   Default value is
   ";party=calling;id-type=subscriber;screen=yes".

   Example 1-4. rpid_suffix parameter example
modparam("auth", "rpid_suffix", "@1.2.3.4>")
     _________________________________________________________

1.3.5. realm_prefix (string)

   Prefix to be automatically strip from realm. As an alternative
   to SRV records (not all SIP clients support SRV lookup), a
   subdomain of the master domain can be defined for SIP purposes
   (like sip.mydomain.net pointing to same IP address as the SRV
   record for mydomain.net). By ignoring the realm_prefix "sip.",
   at authentication, sip.mydomain.net will be equivalent to
   mydomain.net .

   Default value is empty string.

   Example 1-5. realm_prefix parameter example
modparam("auth", "realm_prefix", "sip.")
     _________________________________________________________

1.3.6. rpid_avp (string)

   Full AVP specification for the AVP which stores the RPID
   value. It used to transport the RPID value from authntication
   backend modules (auth_db or auth_radius) or from script to the
   auth function append_rpid_hf and is_rpid_user_e164.

   If defined to NULL string, all RPID functions will fail at
   runtime.

   Default value is "$avp(s:rpid)".

   Example 1-6. rpid_avp parameter example
modparam("auth", "rpid_avp", "$avp(i:13)")
     _________________________________________________________

1.4. Exported Functions

1.4.1. www_challenge(realm, qop)

   The function challenges a user agent. It will generate a
   WWW-Authorize header field containing a digest challenge, it
   will put the header field into a response generated from the
   request the server is processing and send the reply. Upon
   reception of such a reply the user agent should compute
   credentials and retry the request. For more information
   regarding digest authentication see RFC2617.

   Meaning of the parameters is as follows:

     * realm - Realm is a opaque string that the user agent
       should present to the user so he can decide what username
       and password to use. Usually this is domain of the host
       the server is running on.
       If an empty string "" is used then the server will
       generate it from the request. In case of REGISTER requests
       To header field domain will be used (because this header
       field represents a user being registered), for all other
       messages From header field domain will be used.
       The string may contain pseudo variables.
     * qop - Value of this parameter can be either "1" or "0".
       When set to 1 then the server will put qop parameter in
       the challenge. When set to 0 then the server will not put
       qop parameter in the challenge. It is strongly recommended
       to use qop parameter, however there are still some user
       agents that cannot handle qop parameter properly so we
       made this optional. On the other hand there are still some
       user agents that cannot handle request without qop
       parameter too.

   This function can be used from REQUEST_ROUTE.

   Example 1-7. www_challenge usage
...
if (www_authorize("siphub.net", "subscriber")) {
        www_challenge("siphub.net", "1");
};
...
     _________________________________________________________

1.4.2. proxy_challenge(realm, qop)

   The function challenges a user agent. It will generate a
   Proxy-Authorize header field containing a digest challenge, it
   will put the header field into a response generated from the
   request the server is processing and send the reply. Upon
   reception of such a reply the user agent should compute
   credentials and retry the request. For more information
   regarding digest authentication see RFC2617.

   Meaning of the parameters is as follows:

     * realm - Realm is a opaque string that the user agent
       should present to the user so he can decide what username
       and password to use. Usually this is domain of the host
       the server is running on.
       If an empty string "" is used then the server will
       generate it from the request. From header field domain
       will be used as realm.
       The string may contain pseudo variables.
     * qop - Value of this parameter can be either "1" or "0".
       When set to 1 then the server will put qop parameter in
       the challenge. When set to 0 then the server will not put
       qop parameter in the challenge. It is strongly recommended
       to use qop parameter, however there are still some user
       agents that cannot handle qop parameter properly so we
       made this optional. On the other hand there are still some
       user agents that cannot handle request without qop
       parameter too.

   This function can be used from REQUEST_ROUTE.

   Example 1-8. proxy_challenge usage
...
if (!proxy_authorize("", "subscriber)) {
        proxy_challenge("", "1");  # Realm will be autogenerated
};
...
     _________________________________________________________

1.4.3. consume_credentials()

   This function removes previously authorized credentials from
   the message being processed by the server. That means that the
   downstream message will not contain credentials there were
   used by this server. This ensures that the proxy will not
   reveal information about credentials used to downstream
   elements and also the message will be a little bit shorter.
   The function must be called after www_authorize or
   proxy_authorize.

   This function can be used from REQUEST_ROUTE.

   Example 1-9. consume_credentials example
...
if (www_authorize("", "subscriber)) {
    consume_credentials();
};
...
     _________________________________________________________

1.4.4. is_rpid_user_e164()

   The function checks if the SIP URI received from the database
   or radius server and will potentially be used in
   Remote-Party-ID header field contains an E164 number
   (+followed by up to 15 decimal digits) in its user part. Check
   fails, if no such SIP URI exists (i.e. radius server or
   database didn't provide this information).

   This function can be used from REQUEST_ROUTE.

   Example 1-10. is_rpid_user_e164 usage
...
if (is_rpid_user_e164()) {
    # do something here
};
...
     _________________________________________________________

1.4.5. append_rpid_hf()

   Appends to the message a Remote-Party-ID header that contains
   header 'Remote-Party-ID: ' followed by the saved value of the
   SIP URI received from the database or radius server followed
   by the value of module parameter radius_rpid_suffix. The
   function does nothing if no saved SIP URI exists.

   This function can be used from REQUEST_ROUTE, FAILURE_ROUTE,
   BRANCH_ROUTE.

   Example 1-11. append_rpid_hf usage
...
append_rpid_hf();  # Append Remote-Party-ID header field
...
     _________________________________________________________

1.4.6. append_rpid_hf(prefix, suffix)

   This function is the same as Section 1.4.5. The only
   difference is that it accepts two parameters--prefix and
   suffix to be added to Remote-Party-ID header field. This
   function ignores rpid_prefix and rpid_suffix parameters,
   instead of that allows to set them in every call.

   Meaning of the parameters is as follows:

     * prefix - Prefix of the Remote-Party-ID URI. The string
       will be added at the begining of body of the header field,
       just before the URI.
     * suffix - Suffix of the Remote-Party-ID header field. The
       string will be appended at the end of the header field. It
       can be used to set various URI parameters, for example.

   This function can be used from REQUEST_ROUTE, FAILURE_ROUTE,
   BRANCH_ROUTE.

   Example 1-12. append_rpid_hf(prefix, suffix) usage
...
append_rpid_hf("", ";party=calling;id-type=subscriber;screen=yes");  #
Append Remote-Party-ID header field
...
     _________________________________________________________

Chapter 2. Developer's Guide

   The module does not provide any API to use in other OpenSER
   modules.
     _________________________________________________________

Chapter 3. Frequently Asked Questions

   3.1. Where can I find more about OpenSER?
   3.2. Where can I post a question about this module?
   3.3. How can I report a bug?

   3.1. Where can I find more about OpenSER?

   Take a look at http://openser.org/.

   3.2. Where can I post a question about this module?

   First at all check if your question was already answered on
   one of our mailing lists:

     * User Mailing List -
       http://openser.org/cgi-bin/mailman/listinfo/users
     * Developer Mailing List -
       http://openser.org/cgi-bin/mailman/listinfo/devel

   E-mails regarding any stable OpenSER release should be sent to
   <users@openser.org> and e-mails regarding development versions
   should be sent to <devel@openser.org>.

   If you want to keep the mail private, send it to
   <team@openser.org>.

   3.3. How can I report a bug?

   Please follow the guidelines provided at:
   http://sourceforge.net/tracker/?group_id=139143.
