[Ecn-sane] cautionary tcp tale

[Jonathan Morton]

> On 13 Aug, 2019, at 12:30 am, Dave Taht <dave.taht at gmail.com> wrote:
> 
> https://www.snellman.net/blog/archive/2017-07-20-s3-mystery/

TL;DR summary:

Buggy checksum recalculation in a cable modem caused minor packet loss (through rejection at the receiver).  In the absence of TCP Timestamps, the retransmissions of these lost packets were identical and triggered the same bug.  Result, connections to certain particular servers which had the unusual property of disabling TCP Timestamps would quickly stall.

I think a tool could be made to watch a sample of received traffic for this pattern: incorrect checksums where the correct checksum is the same each time (though different per deployment).  How much network equipment exhibits this bug?

 - Jonathan Morton