Subject: Re: CVS commit: src/sys/netinet
To: David Laight <>
From: Perry E. Metzger <>
List: source-changes
Date: 09/06/2003 14:01:49
David Laight <> writes:
> I'm not sure that arc4random is appropriate for ip sequence numbers,
> it doesn't have the correct properties.  In particular the same output
> value can be generated by adjacent calls to the function - which you
> definitely don't want!  This will be true for any generator with more
> that 32 bits of state (or rather if the required value is smaller than
> the state).

Ideally, we want something that generates an unpredictable ergodic
sequence of some sort -- that is to say, a sequence guaranteed to
cycle through all possible values, but in an unpredictable order.

I'm not entirely sure what the right way to do this is, though.

Perry E. Metzger