identifying single computers

I need help dealing with a programmer

[greenleaves]

Hi,

Ok. I have a programer who doesn't seem to believe it is possible to identify several loggins from different IPs comming from the same computer.

I've worked in places where this is possible... but since I'm not a programer, I can't exmplain to him what/how it is done.

Could someone please lend me a hand?

Thanks

[graeme_p]

You can do it on your local subnet (i.e. your LAN) using MAC addreses.

AFAIK you cannot do this to arbitrary machines somewhere else on the internet. I would be quite interested to know how to do it, if it is possible!

[phranque]

it depends on the specifics of the question.
if the user agent is the same at each ip location and cookies are supported and not cleared it would be possible to uniquely identify a returning visitor.
for example, WebmasterWorld uses cookies [webmasterworld.com] to keep members logged in.
when i connect through a different ip than usual i get properly identified.

[enigma1]

yes and even if cookies are off, passing something like a session identifier over the url is enough.

Some web engines are designed like this, in order to support sites that are hosted on shared servers and utilize a shared SSL and therefore exclusive use of cookies is out of the question.

[SarK0Y]

it's possible if clientside have neccessary facilities, but crackers are being in the our world:)))