Subject: RE: [Sip] INFO considered harmful

From: Adam Roach <[email-masked]>
Date: Fri, 3 Jan 2003 14:14:42 -0600

> From: Henning Schulzrinne [mailto:[email-masked]]
>
> In general, I just don't buy server load arguments. If it's a
> useful service, server cost is usually the least of the problem.
> In any event, one should take this as a fraction of the existing
> signaling load, not as some absolute number. I'm worried about
> stuff that multiplies the signaling load by a factor of 10; I find
> 20 or 50% load increase uninteresting as an argument.

You don't buy server load arguments? Real-world experience
notwithstanding?

I'm recalling the rise in popularity of Real Media Player and
its ability to set up an audio stream through an HTTP proxy.
In particular, I'm recalling conversations shortly thereafter
with some friends over in MIS about how they just couldn't add
capacity to the HTTP proxy pool fast enough to keep up with
demand.

Access to external web documents sometimes creeped up to the
order of minutes before everything was finally stabilized.

How long do you guess it will be before Real player
(or a similar product) includes a "SIP Proxy:" field right
next to its "HTTP Proxy:" field for firewall circumvention?

/a
_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip

---

From: Henning Schulzrinne <[email-masked]>
Date: Fri, 03 Jan 2003 15:22:05 -0500

Your example clearly falls into the "> 10" category as the poor web 
server had to deal with every Real audio or video packet. Not that it 
would surprise me, but I don't think anybody *here* has suggested 
RTP-over-INFO so far.

---

From: Christer Holmberg <[email-masked]>
Date: Thu, 09 Jan 2003 10:45:49 +0200

Hi,

> would surprise me, but I don't think anybody *here* has suggested

Isn't that part of the missuse problem we are talking about here - that
someone actually COULD start using INFO for sending RTP (or whatever else
that would creating frequent message sending)?

Regards,

Christer Holmberg
Ericsson Finland

---

From: Henning Schulzrinne <[email-masked]>
Date: Thu, 09 Jan 2003 07:47:55 -0500

The same is true for any message. Heck, you could probably encapsulate 
RTP in ACK or (intentionally rejected) INVITE, if ACK or INVITE doesn't 
get charged.

---

From: Christer Holmberg <[email-masked]>
Date: Thu, 09 Jan 2003 15:09:09 +0200

Hi,

> RTP in ACK or (intentionally rejected) INVITE, if ACK or INVITE doesn't

That was exactly my point in the beginning of the thread, when I asked if we
need to define what kind of message bodies/information we are allowed to
include in INVITE and UPDATE.

Regards,

Christer Holmberg
Ericsson Finland

---

From: Henning Schulzrinne <[email-masked]>
Date: Thu, 09 Jan 2003 10:24:49 -0500

The good guys don't need the restriction, the bad guys will ignore it. 
This all comes down to economic incentives: if it costs less to send a 
message of type foo than type bar (where 'costs less' may mean that the 
alternative has infinite cost, since the firewall won't let it pass), 
users will find that interesting, whether we proscribe it or not.

We don't worry about what you can attach to an email message, even 
though this also consumes precious server resources. (We obviously 
should and do worry what you do to the shared network resources.) If a 
proxy wants to reject all INFO messager or rate-limit a particular 
sender or restrict the size or content of messages, that's its privilege.

---

From: Christer Holmberg <[email-masked]>
Date: Thu, 09 Jan 2003 17:39:26 +0200

Hi,

> sender or restrict the size or content of messages, that's its privilege.

If that is the solution, I see no reason for this whole thread :) There is no idea
to put any restrictions on INFO either, because the bad guys will ignore it
anyway...

Regards,

Christer Holmberg
Ericsson Finland

---

From: "Dean Willis" <[email-masked]>
Date: Thu, 9 Jan 2003 18:13:49 -0600

Yep. Several university hacker groups tunneled IP over DNS back when
firewalls first reared their eugly heads in the early '90s. You know, it
doesn't specifically say "Thou shalt not tunnel IP over domain xfer
requests" in the DNS spec, and I'm sure if it had, that they would not have
done this.

--
Dean