Subject: RE: [BEEPwg] Firewall Traversal

From: Doug Ransom <[email-masked]>
Date: Wed, 20 Mar 2002 13:35:46 -0800

I am talking about a typical firewall with NAT or PAT that I would expect to
see at most organizations.  
 
It seems to me that if the peers require a continous  connection to the
proxy that this could be costly -- the proxy would need a lot of open
connections for a lot of clients.   Does that scale well?

[Doug Ransom]  
From: james woodyatt [mailto:[email-masked]]
Sent: Wednesday, March 20, 2002 1:24 PM
To: Doug Ransom
Cc: [email-masked]'
Subject: Re: [BEEPwg] Firewall Traversal

On Wednesday, March 20, 2002, at 12:33 PM, Doug Ransom wrote: 

I am trying to understand how peers might traverse a firewall.  In the
instant message scenario, would a peer need a continous tcp or beep
connection to an outside proxy in order to receive messages from another
peer? 

The answer is "yes," "no," or "maybe" --depending on the sort of firewall. 

If the firewall is not a network-layer filtering firewall, and it doesn't
transparently route Internet packets, then by its definition: you need a
proxy for your instant messaging application. 

If the firewall is a network-layer filtering firewall, and it *does*
transparently route Internet packets, then by its definition: you do not
need a proxy for your instant messaging application. (You may need to apply
appropriate policies.) 

If the firewall is a network-layer filtering firewall *and* it is integrated
with a network address translation function, then your instant messaging
application may need an application layer gateway in the firewall, or it may
need a rendezvous service residing elsewhere on the network. 

What sort of firewall are you talking about? 

-- 

j h woodyatt <[email-masked]>

---

From: james woodyatt <[email-masked]>
Date: Wed, 20 Mar 2002 14:01:49 -0800

On Wednesday, March 20, 2002, at 01:35 PM, Doug Ransom wrote:
>
> [...] It seems to me that if the peers require a continous connection 
> to the proxy that this could be costly -- the proxy would need a lot of 
> open connections for a lot of clients.   Does that scale well?

I'm given to understand that the proprietary AOL instant messenger 
application is built to this architecture.  I'm not sure that answers 
your question, though...

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