Re: time-server question

Even the *concept* of an accurate timestamp is problematic in most operating systems. I
remember when Xerox developed an algorithm for synchronizing the timestamps of their
internal workstations, which would be accurate to about 20ms. This was considered "close
enough" for most purposes. But an absolute timestamp is a pretty flaky concept. The best
you can hope for is a time that is within a few seconds of a time server. Mostly, you
will be off by a larger margin.

Real-time embedded kernels actually have a concept of time, and in something like that you
have a small chance of getting a time that is accurate within a fraction of a second,
providing you have compensated for things like round-trip network delays and other such
trivia. But a general-purpose OS such as Windows, Unix, Linux, Solaris, Mac OS X, etc.
have at best a fairly loose concept of the notion of "time", both relative and absolute.
Time is something that sort of moves forward at some kind of rate, more or less.
joe

On Tue, 28 Nov 2006 20:42:22 -0000, "Mark Randall" <markyr@xxxxxxxxxxxxxx> wrote:

If a user has your your app running in a non-standard priority, or your
threads get paused, or if there is a bad network connection, or...

Then your application is wrong anyway.

What you are wanting is *secure time* which is, on windows systems, pretty
much impossible.
Joseph M. Newcomer [MVP]
email: newcomer@xxxxxxxxxxxx
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm
.

Relevant Pages

  • [REVS] TCP Timestamp and Advanced Fingerprinting
    ... The following security advisory is sent to the securiteam mailing list, and can be found at the SecuriTeam web site: http://www.securiteam.com ... current and average uptime of specific operating systems running on the ... By grabbing the value of timestamp of such operating system ... TCP timestamps values are inserted in many TCP packets (such as SYN, ...
    (Securiteam)
  • TCP timestamp & advanced fingerprinting
    ... attached is a paper from one of our students about using the TCP ... analysis of various operating systems should reveal how analyzing timestamps ... the timestamp value of one point each 500 milliseconds. ... value in their SYN packets, but Windows-based operating systems does not. ...
    (Bugtraq)