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From Costin Manolache <>
Subject Re: Duplicate session IDs are *common*
Date Thu, 09 Jan 2003 03:37:28 GMT
Schnitzer, Jeff wrote:

> For whatever reason, be it the seed algorithm or the hashing algorithm
> or something else that degenerates the randomness - the duplicate
> session ID problem is very, very common.
> I discovered this problem because a few of our users suddenly found
> themselves with the sessions from administrative accounts.  Luckily they
> alerted us instead of causing mayhem.  There were at least three
> separate occasions of this in the last week - that we heard about.
> We have also seen this a number of times with other game components -
> users suddenly finding themselves logged in as other people.
> It probably explains the recent post to tomcat-user included below.
> Here at my company this problem caused about as much panic as a wildfire
> breaking out in the machine room (read: LOTS).  I humbly suggest raising
> the level of concern a bit; post a security bulletin, etc.

What version of tomcat ? Are you on Linux ? What randomClass are you using ?
How many sessions are usually generated ?

The default is - and should give enough 
randomness. There is a change on head ( that would work with 5.0 - but
it can be backported ) that allow you to use /dev/urandom ( or another
source - it can be a pipe or something like that ). 


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