0trace enables the user to perform hop enumeration (“traceroute”) within an established TCP connection, such as a HTTP or SMTP session. This is opposed to sending stray packets, as traceroute-type tools usually do. The important benefit of using an established connection and matching TCP packets to send a TTL-based probe is that such traffic is happily allowed through by many stateful firewalls and other defenses without further inspection (since it is related to an entry in the connection table).
Backtrack 5 R1
root@bt:/pentest/enumeration/0trace# ./0trace.sh eth0 (IP ADDRESS1)
0trace v0.01 PoC by <email@example.com>
[+] Waiting for traffic from target on eth0…
you need to then open another terminal and connect using netcat as bellow
root@bt:~# nc (IP ADDRESS1) 80
GET / HTTP/1.0