RE: Securing VOIP?

From: Shawn Duffy (sduffyat_private)
Date: Mon Oct 15 2001 - 16:18:26 PDT

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    Your provider is correct.  PRI is a switched service provided by HIS/HER
    side.  The only way that data (we are talking about Internet traffic
    from the providers side) can get through is by the provider allowing it.
    
    
    My guess is he is providing you B channels directly from the provider's
    own PBX.  This means that he is hooking you up to PHONE services only.
    I bet he hasn't thought of you using the channel for dial into an analog
    modem...  Even so, the issue would be with the terminating modem on your
    end.
    More likely you are running a digital service and cannot hook an analog
    modem to your phone set.
    
    Clear as mud now?
    Hope this did help.
    
    --
    Shawn Duffy, CISSP
     
     
    
    
    -----Original Message-----
    From: rebercat_private [mailto:rebercat_private] 
    Sent: Monday, October 15, 2001 11:13 AM
    To: pen-testat_private
    Subject: Securing VOIP?
    
    
    Hi 
    
    I have to review our concept for implementing VOIP. I have to make sure,
    that all security issues are covered. If anybody could give me some help
    on this question:
    
    Our provider says, that we need no firewall for VOIP because our Voice
    Gateway receives only PRI requests/transfers. He says that it is
    possible to restrict the Voice Gateway for only PRI-Traffic and that it
    is impossible to bring data along with PRI. The PRI is always converted
    to voice. Now I have seen, that you can send Voice, Video and Data on
    PRI. Is it really necessary to have an Firewall between our CallManager
    and Voice Gateway or can I trust the provider and be sure, that nothing
    else (IP-Transfers) is coming over this line? 
    
    Many thanks in advance!
    
    Claudia Reber
    IT-Security Officer
    
    Die Schweizerische Post
    Information Technology Services
    IT5 IT-Security
    Webergutstrasse 12
    CH-3030 Bern (Zollikofen)
    
    Tel: 	++41 (0)31 338 16 44
    Handy:	++41 (0)79 211 01 48
    Fax:	++41 (0)31 338 74 92
    > e-Mail mailto:rebercat_private
    > 
    > visit our homepage:
    > http://pww.post.ch/oe/IP/corp//index.htm (intern) http://www.post.ch 
    > (extern)
    > 
    > 
    There was a belief that it was going to be easy. They were wrong!
    
    
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