Re: [Sip] TLS post connection verification

["James Ford" <james_s_ford@hotmail.com>]

Hi Eron,
The standard does not elaborate on that, but here is what I think:

For the second question: for sending responses on broken connections, I 
don't think that there is a need to do post connection assertion. for two 
reasons:
a - The server does not need to authenticate the client.
b - allot of applications put their specific IP address on the via field 
while a certificate is more likely issued to an FQDN.

The first question is more tricky. My guess is the "incoming" connection 
should only check for the correctness of the certificate and not do a post 
connection assertion. This might be a security issue though. Maybe someone 
with some hands on experience can would be more helpful here.

Regards,
James S. Ford


> Hi,
>
> When sending a request (ie REGISTER) to a server I can compare the request
> URI to the common name (or the alt dns name) in the certificate. If the
> names match, I can conclude that the certificate is OK.
> (I'm using OpenSSL, and they recommend this post connection assertion).
>
> I have two questions thou:
>
> 1 - What name should I use for comparison when accepting a connection?
> Usually only the UAC will demand certificate, I am concerned with te case 
> of
>
> two proxies trying to connect using TLS and the UAS proxy asking for client
> certificates. (what uri will the UAS proxy has, there is no message yet).
>
> 2 - how should broken connection be handled? lets say UAC1 sent a request
> over TLS to UAS1. the handshake went well and the request sent. than for
> some reason, the connection was broken and UAS1 now needs to reestablish 
> the
>
> connection. What should UAS1 do? use TLS w/out certificates?
>
>
> Regards,
> Eron Stein
>
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_______________________________________________
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This list is for NEW development of the core SIP Protocol
Use sip-implementors@cs.columbia.edu for questions on current sip
Use sipping@ietf.org for new developments on the application of sip