15 lines
842 B
Plaintext
15 lines
842 B
Plaintext
The more traditional traceroute(8) sends out either UDP or ICMP ECHO
|
|
packets with a TTL of one, and increments the TTL until the destination
|
|
has been reached. By printing the gateways that generate ICMP time
|
|
exceeded messages along the way, it is able to determine the path
|
|
packets are taking to reach the destination.
|
|
|
|
The problem is that with the widespread use of firewalls on the modern
|
|
Internet, many of the packets that traceroute(8) sends out end up being
|
|
filtered, making it impossible to completely trace the path to the
|
|
destination. However, in many cases, these firewalls will permit inbound
|
|
TCP packets to specific ports that hosts sitting behind the firewall are
|
|
listening for connections on. By sending out TCP SYN packets instead of
|
|
UDP or ICMP ECHO packets, tcptraceroute is able to bypass the most common
|
|
firewall filters.
|