tcptraceroute:tldr:7c75a

The command tcptraceroute ${host} -i ${interface} is used to perform a traceroute with TCP packets instead of the default ICMP packets.

Here's an explanation of the command elements:

• ${host}: This is a placeholder for the host or IP address that you want to perform the traceroute to. It should be replaced with the actual destination you want to trace, e.g., a domain name or IP address.
• -i ${interface}: This option specifies the network interface to use for sending the traceroute packets. ${interface} is a placeholder for the specific interface name, which should be replaced with the appropriate interface like eth0, wlan0, etc.

When you run this command, it will initiate a TCP traceroute by sending TCP packets with increasing time-to-live (TTL) values to the specified ${host} through the specified ${interface}. Each packet is assigned a different TTL value, starting from 1 and increasing incrementally. As the packets traverse the network, they will reach routers along the path to the destination.

When a router receives a TCP packet with a TTL value of 1, it will drop the packet and send an ICMP "Time Exceeded" message back to the source. This allows the traceroute program to identify the first hop. By increasing the TTL value, the traceroute program can determine subsequent hops by observing the routers that respond with "Time Exceeded" messages.

The TCP traceroute process continues until the target ${host} is reached or until a maximum number of hops or a timeout is reached. The output of the command will display the IP addresses or hostnames of the routers traversed along with information about RTT (Round Trip Time) and TTL values.

In summary, the command tcptraceroute ${host} -i ${interface} is used to perform a TCP-based traceroute to ${host} through the specified network ${interface}.