Remote OS identification

 Xprobe2 allows you to determine what operating system is running on a
 remote host. It sends several packets to a host and analyses the
 returned answers.
 .
 Xprobe2's functionality is comparable to the OS fingerprinting feature
 in nmap (written by a different Fyodor):
  - Outputs its level of confidence about the OS on the remote host.
  - Remains usable even if intermediate systems (routers, firewalls) make
    slight modifications to the packets.
  - Can list the type of intermediate device (e.g. "Linux IP masquerading").
  - Modular architecture allows new fingerprinting tests and new OS
    signatures to be added.