[142513] in North American Network Operators' Group
Re: Strange TCP connection behavior 2.0 RC2 (+3)
daemon@ATHENA.MIT.EDU (Cameron Byrne)
Wed Jun 29 10:35:17 2011
In-Reply-To: <bf9c1ec5-fadc-43f6-a61b-be01bcd99897@35g2000prp.googlegroups.com>
Date: Wed, 29 Jun 2011 07:34:26 -0700
From: Cameron Byrne <cb.list6@gmail.com>
To: Ryan Malayter <malayter@gmail.com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Jun 29, 2011 6:00 AM, "Ryan Malayter" <malayter@gmail.com> wrote:
>
>
>
> On Jun 28, 3:35 pm, Cameron Byrne <cb.li...@gmail.com> wrote:
>
> >
> > AFAIK, Verizon and all the other 4 largest mobile networks in the USA
> > have transparent TCP proxies in place.
>
> Do you have a reference for that information? Neither AT&T nor Sprint
No.
> seem to have transparent *HTTP* proxies according to
> http://www.lagado.com/tools/cache-test. I would have thought that
> would be the first and most important optimization a mobile carrier
> could make. I used to see "mobile-optimized" images and HTTP
> compression for sites that weren't using it at the origin on Verizon's
> 3G network a few years ago, so Verizon clearly had some form of HTTP
> proxy in effect.
>
> Aside from that, how would one check for a transparent *TCP* proxy? By
> looking at IP or TCP option fingerprints at the receiver? Or comparing
> TCP ACK RTT versus ICMP ping RTT?
>
I am not familiar with that HTTP proxy test.
As I said, they are likely using tcp proxies to get over tcp issues. I
assume if you were sniffing both ends you could discover changes in
parameters forced by the middle box.
Cb
