Niels Provos Honeyd before 1.5 replies to certain illegal IP packet fragments that other IP stack implementations would drop, which allows remote attackers to identify IP addresses that are being simulated using honeyd.
https://exchange.xforce.ibmcloud.com/vulnerabilities/24728
http://www.vupen.com/english/advisories/2006/0552
http://www.securityfocus.com/bid/16595
http://www.securityfocus.com/archive/1/425112/100/0/threaded
http://www.honeyd.org/phpBB2/viewtopic.php?t=106