Re: TCP Timestamping and Remotely gathering uptime information

[Theo de Raadt <deraadt () CVS OPENBSD ORG>]

> Darren Reed said:
>
> > Why do you think all timestamps should not reveal uptime information ?
>
> Well, not to speak on Bret's behalf per se, but personally, I've seen
> plenty of software (the quality of which may be in question) that uses
> uptime (or clock-ticks-since-boot, whatever) for a variety of things,
> albeit ususally trivial.

Lots of such things exist.  One example is RPC, which used to generate
it's initial XID (which are subsequently incremented per transaction)
from tv.tv_sec ^ tv.tv_usec ^ getpid().  On systems with predictable
boot sequences, predictable pids, and known boot time, it is possible
to figure out the window of XID usage, and spoof replies.

Other such thigns do exist, get discovered, etc etc etc, and fixed on
their own.  However, ... it's nice to fix problems by accident.