Honeyd 1.5c

Honeyd is an open source computer program that allows a user to set up and run multiple virtual hosts on a computer network. These virtual hosts can be configured to mimic several different types of servers, allowing the user to simulate an infinite number of computer network configurations.

The primary purpose of Honeyd is detection, specifically to detect unauthorized activity within your organization by monitoring all unused IPs in the network. Any attempted connection (port scans, vulnerability scans etc) to an unused IP address is assumed to be unauthorized or malicious activity.

In addition to detection, Honeyd can also create emulated services which interact with the attacker. It is used to create multiple virtual honeypots on a single machine. Therefore entire networks can be simulated using honeyd. Honeyd can be configured to run a range of services like FTP, HTTP, or SMTP. Furthermore, a personality can be configured to simulate behaviour of a certain operating system. Honeyd allows a single host to claim as many as 65536 IP addresses.

Download Honeyd here
Honeyd 1.5c

A Windows port of Honeyd, developed by netVigilance Inc, can be found here:
winHoneyd