RE: Real Audio Security

From: arkat_private
Date: Fri Jan 21 2000 - 02:06:59 PST

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    nuqneH,
    
    Hmmm ;) AFAIR Gauntlet has its own RA proxy, probably based on PN's 
    reference implementation available from their site - what's wrong 
    with it , why should you use web proxy ;)? 
    
    Ah! Bashing socks i forgot another problem with it: if you use firewall
    to control what your users do on the net, socks (if you don't spend
    some amount of time to configure it for selected applications and hosts
    only) is a way for them to avoid your control. All you see from
    socks log is just host addresses and port numbers and no knowledge what
    they actually do, not more than packet filtering can provide to you.
    
    And the biggest problem with socks is that most firewall administrators
    are NOT aware of the problems i mentioned.
    
    - ----
    
    "LeGrow, Matt" <Matt_LeGrowat_private> said :
    
    While researching a problem with the Gauntlet 5.0 web proxy a while
    back I had a chance to observe RealAudio traffic tunnelling itself
    through our web proxy.    RealAudio actually allows you to configure
    or gives the option to determine for itself the best method out of
    several types of transport, including TCP and UDP-based transports. 
    As if thats not confusing enough, there are also two different
    versions of the TCP transport protocol to choose from, either RTSP
    (TCP port 554) or PNA (TCP port 1090).  The UDP-based transport uses
    both multiple single ports and a range of UDP ports.
    
    So the least complicated thing is to just tell it to run through your
    Web Proxy.  Through a web proxy, at least,I can tell you that
    RealAudio sends some strange traffic through, including mysterious
    encoded/encrypted (?) 5k POSTs on a fairly consistent basis (with
    Spinner we were able to match them to the ends of songs that we
    played through the client) that I assume are encoded requests or
    updates of state information to the realaudio server.  With the two
    clients I was testing with (Spinner and RealPlayer 6.0.6.45) the POST
    requests were adorned with incorrect content-lengths and
    non-Y2K-compliant expiration dates for content.  Just not knowing
    what the thing is posting through your firewall should make any
    reasonably paranoid admin nervous enough.
    
    I would say just on external observation and not knowing the guts of
    the protocol, that its definitely a big black hole, but if you must
    proxy it set up a TCP/SOCKS proxy instead of burdening your web proxy
    with the additional barely-compliant HTTP traffic
    - ---
    
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