Fingerprinting IDS sensors?

"Chen, Hao" <[email protected]> Mon, 8 Jun 2009 15:15:37 +0100

Newsgroups	gmane.comp.security.ids
Message-ID	<[email protected]>

Hi,

I'm wondering if it is possible for an attacker to know/aware that a
target site has already had IDS products deployed? If yes, how? An
example would help, Thanks a lot!

Regards