Peering Module

Juha Heinanen

   <jh@tutpro.com>

Edited by

Juha Heinanen

   <jh@tutpro.com>

   Copyright © 2008 Juha Heinanen
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications

        3. Exported Parameters

              3.1. radius_config (string)
              3.2. verify_destination_service_type (integer)
              3.3. verify_source_service_type (integer)

        4. Exported Functions

              4.1. verify_destination()
              4.2. verify_source()

   List of Examples

   1.1. radius_config parameter usage
   1.2. verify_destination_service_type parameter usage
   1.3. verify_source_service_type parameter usage
   1.4. verify_destination() usage
   1.5. verify_source() usage

Chapter 1. Admin Guide

   Table of Contents

   1. Overview
   2. Dependencies

        2.1. Kamailio Modules
        2.2. External Libraries or Applications

   3. Exported Parameters

        3.1. radius_config (string)
        3.2. verify_destination_service_type (integer)
        3.3. verify_source_service_type (integer)

   4. Exported Functions

        4.1. verify_destination()
        4.2. verify_source()

1. Overview

   The peering module allows SIP providers (operators or organizations) to
   verify from a broker if source or destination of a SIP request is a
   trusted peer.

   In order to participate in the trust community provided by a broker,
   each SIP provider registers the domains (host parts of SIP URIs) that
   they serve with the broker. When a SIP proxy of a provider needs to
   send a SIP request to a non-local domain, it can find out from the
   broker using verify_destination() function if the non-local domain is
   served by a trusted peer. If so, the provider receives from the broker
   a hash of the SIP request and a timestamp that it includes in the
   request to the non-local domain. When a SIP proxy of the non-local
   domain receives the SIP request, it, in turn, can verify from the
   broker using verify_source() function if the request came from a
   trusted peer.

   Verification functions communicate with the broker using Radius
   protocol. Sample FreeRADIUS configuration files for broker's Radius
   server are available from http://www.wirlab.net/tsi/.

   Comments and suggestions for improvements are welcome.

2. Dependencies

   2.1. Kamailio Modules
   2.2. External Libraries or Applications

2.1. Kamailio Modules

   The module depends on the following modules (in the other words the
   listed modules must be loaded before this module):
     * none

2.2. External Libraries or Applications

   The following libraries or applications must be installed before
   compilling Kamailio with this module loaded:
     * radiusclient-ng 0.5.0 or higher -- library and development files.
       See http://developer.berlios.de/projects/radiusclient-ng/.

3. Exported Parameters

   3.1. radius_config (string)
   3.2. verify_destination_service_type (integer)
   3.3. verify_source_service_type (integer)

3.1. radius_config (string)

   This is the location of the configuration file of Radius client
   libraries.

   Default value is “/usr/local/etc/radiusclient-ng/radiusclient.conf”.

   Example 1.1. radius_config parameter usage
modparam("peering", "radius_config", "/etc/broker/radiusclient.conf")

3.2. verify_destination_service_type (integer)

   This is the value of the Service-Type Radius attribute to be used, when
   sender of SIP Request verifies the request's destination using
   verify_destination() function.

   Default value is the dictionary value of “Sip-Verify-Destination”
   Service-Type.

   Example 1.2. verify_destination_service_type parameter usage
modparam("peering", "verify_destination_service_type", 21)

3.3. verify_source_service_type (integer)

   This is the value of the Service-Type Radius attribute to be used, when
   receiver of SIP Request verifies the request's source using
   verify_source() function.

   Default value is the dictionary value of “Sip-Verify-Source”
   Service-Type.

   Example 1.3. verify_source_service_type parameter usage
modparam("peering", "verify_source_service_type", 22)

4. Exported Functions

   4.1. verify_destination()
   4.2. verify_source()

4.1. verify_destination()

   Function verify_destination() queries from broker's Radius server if
   domain (host part) of Request URI is served by a trusted peer. Radius
   request contains the following attributes/values:
     * User-Name - Request-URI host
     * SIP-URI-User - Request-URI user
     * SIP-From-Tag - From tag
     * SIP-Call-Id - Call id
     * Service-Type - verify_destination_service_type

   Function returns value 1 if domain of Request URI is served by a
   trusted peer and -1 otherwise. In case of positive result, the Radius
   server returns a set of SIP-AVP reply attributes. The value of each
   SIP-AVP is of form:

   [#]name(:|#)value

   Value of each SIP-AVP reply attribute is mapped to an Kamailio AVP.
   Prefix # in front of name or value indicates a string name or string
   value, respectively.

   One of the SIP-AVP reply attributes contains a string that the source
   peer must include "as is" in a P-Request-Hash: header when it sends the
   SIP request to the destination peer. The string value may, for example,
   be of form hash@timestamp, where hash contains a hash calculated by the
   broker based on the attributes of the query and some local information
   and timestamp is the time when the calculation was done.

   AVP names used in reply attributes are assigned by the broker.

   This function can be used from REQUEST_ROUTE and FAILURE_ROUTE.

   Example 1.4. verify_destination() usage
...
if (verify_destination()) {
   append_hf("P-Request-Hash: $avp(i:200)\r\n");
}
...

4.2. verify_source()

   Function verify_source() queries the broker's Radius server whether the
   SIP request was received from a trusted peer. The Radius request
   contains the following attributes/values:
     * User-Name - Request-URI host
     * SIP-URI-User - Request-URI user
     * SIP-From-Tag - From tag
     * SIP-Call-Id - Call id
     * SIP-Request-Hash - body of P-Request-Hash header
     * Service-Type - verify_source_service_type

   Function returns value 1 if SIP request was received from a trusted
   peer and -1 otherwise. In case of positive result, Radius server may
   return a set of SIP-AVP reply attributes. Value of each SIP-AVP is of
   form:

   [#]name(:|#)value

   Value of each SIP-AVP reply attribute is mapped to an Kamailio AVP.
   Prefix # in front of name or value indicates a string name or string
   value, respectively.

   AVP names used in reply attributes are assigned by the broker.

   This function can be used from REQUEST_ROUTE and FAILURE_ROUTE.

   Example 1.5. verify_source() usage
...
if (is_present_hf("P-Request-Hash")) {
   if (verify_source()) {
      xlog("L_INFO", "Request came from trusted peer\n")
   }
}
...