---
title: "Peering Module"
description: "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."
---

## Admin Guide


### Overview


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 with the broker the domains
(host parts of SIP URIs) that they serve.  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 an AAA
protocol.


Comments and suggestions for improvements are welcome.


### Dependencies


#### OpenSIPS Modules


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


- *an AAA implementing module*


### Exported Parameters


#### aaa_url (string)


This is the url representing the AAA protocol used and the location of the configuration file of this protocol.


If the parameter is set to empty string, the AAA accounting support
will be disabled (even if compiled).


Default value is "NULL".


```opensips title="Set aaa_url parameter"
...
modparam("peering", "aaa_url", "radius:/etc/radiusclient-ng/radiusclient.conf")
...
```


#### verify_destination_service_type (integer)


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


Default value is dictionary value of "Sip-Verify-Destination"
Service-Type.


```opensips title="verify_destination_service_type parameter usage"
...
modparam("peering", "verify_destination_service_type", 21)
...
```


#### verify_source_service_type (integer)


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


Default value is dictionary value of "Sip-Verify-Source"
Service-Type.


```opensips title="verify_source_service_type parameter usage"
...
modparam("peering", "verify_source_service_type", 22)
...
```


### Exported Functions


#### verify_destination()


Function verify_destination() queries from
broker's AAA server if domain (host part) of Request
URI is served by a trusted peer.  AAA 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, AAA server returns 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
OpenSIPS 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.


```opensips title="verify_destination() usage"
...
if (verify_destination()) {
   append_hf("P-Request-Hash: $avp(prh)\r\n");
}
...
```


#### verify_source()


Function verify_source() queries from
broker's AAA server if SIP request was received from
a trusted peer.  AAA 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, AAA 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
OpenSIPS 
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.


```opensips title="verify_source() usage"
...
if (is_present_hf("P-Request-Hash")) {
   if (verify_source()) {
      xlog("L_INFO", "Request came from trusted peer\n")
   }
}
...
```
<!-- CONTRIBUTORS -->

### License

All documentation files (i.e. .md extension) are licensed under the Creative Common License 4.0
