Fingerprinting an operating system

I am attempting to fingerprint on ou开发者_如何转开发r operating system. However when using nmap it reports that all ports (1000) are filtered. Being extremely new i know this is the network admin's cruel joke and was wondering how to get around this,.

For the record this is for a security class, not malicious behavior

Wes

---

Check out the page on os fingerprinting. It written by the same people who write nmap.