tcptraceroute is a traceroute implementation using TCP packets.

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.

WWW: https://github.com/mct/tcptraceroute