Strange TCP connection behavior 2.0 RC2 (+3)

Cameron Byrne cb.list6 at
Wed Jun 29 14:34:26 UTC 2011

On Jun 29, 2011 6:00 AM, "Ryan Malayter" <malayter at> wrote:
> On Jun 28, 3:35 pm, Cameron Byrne < at> 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


> seem to have transparent *HTTP* proxies according to
> 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.


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