Preventing date rollback

[Stephen J. Friedl]

In article <RICHARD.90Dec3143525 at dataspan.dataspan.UUCP>, richard at dataspan.dataspan.UUCP (Richard "Tiger" Melville) writes:
> Many of the software products our company sells rely on a licence file which
> specifies the duration of time the software is licensed for.  The software
> then refuses to run when the period has expired.  It is, however, possible
> to roll back the date on a machine and fool the licence manager software.

Many sites will not want to set their date back a year (messes up too
many other things), but you can often do it on a per-process basis by
setting a timezone with a *huge* hour offset.  For instance, I can set
my clock back one year by changing

	TZ=PST8PDT
into
	TZ=PST8768PDT		# (24 * 365) + 8 = 8768

Smart software will detect this and refuse to believe a crazy
TZ like this.

     Steve

-- 
Stephen J. Friedl, KA8CMY  /  3B2-kind-of-guy  /  Tustin, CA / 3B2-kind-of-guy
+1 714 544 6561  / friedl at mtndew.Tustin.CA.US  / {uunet,attmail}!mtndew!friedl

"If it doesn't core dump, ship it" - Gary W. Keefe, on product development