[OpenSER-Devel] Cisco x-route-tag

[Klaus Darilion]

Daniel-Constantin Mierla schrieb:
> Hello,
> 
> On 06/18/08 06:11, Davey Goode wrote:
>> Hi All,
>>
>> Traditionally for outbound routing to the PTSN world via a cisco voice 
>> gateway we use HOC's or prefixes,  has anyone ever looked at 
>> incorporating the x-route-tag feature to replace the HOC/ prefix in 
>> openser ???
>>
>> In NZ we have a local code shop that has written a SIP proxy, they 
>> have incorporated it into their proxy and it works great!  it would be 
>> a really nice feature.
>>
>> I would be more than happy to contribute $ if someone wanted to write it.
>>
>> see
>>
>>
>>       http://www.cisco.com/en/US/docs/ios/12_2t/12_2t11/feature/guide/ftgwrepg.html#wp1217685
>>
> did I understand correct that this will be solved by the possibility of 
> adding a custom parameter to the Via header going to be inserted by the 
> proxy itself?

If I understand it right: yes

This is IMO a dangerous feature. The docs says that if the topmost via 
header does not have such a tag it will search for the tags in the the 
other via headers. Thus, for example, if the users SIP client adds the 
parameter and the proxy just forwards the request (with adding a 
parameter itself and without screening existing via parameters) the 
client can enforce a certain trunk.

regards
klaus