[Zope] generate unique user id, without cookies

[Marko Kruijer]

after having some weird issues with Sessions and ZEO usage I've found 
out part of the problem.
It turns out certain browsers (IE6 mostly) save the session ID cookies, 
but sometimes these disappear. This results in a new _ZopeId being 
generated and thus the new session is empty.

At first i thought it was a session product problem, but in recreating 
this with my own session management (mysql based) the same issue arises.

I don't know why this happens, the only obstacle I'm facing now is to 
create an adequate solution ;)

Because the cookie method is not flawless we've decided to create a way 
to uniquely determine a user without using a client side cookie, we are 
already using the IP address for this, Of course that is not enough, so 
I was wondering what other 'unique' elements could be used for this. 
I've thought about adding user agent, but this is to general I think.

Internal IP would be ideal, but I'm not sure this can be done (probably 
not).

Maybe there are also 'other' zope session products that work in another 
way and might fix my problems as a whole?