tcptraceroute:tldr:a5eda

The command "tcptraceroute ${host}" is used to trace the route taken by TCP (Transmission Control Protocol) packets from the source to the specified host.

Here's a breakdown of the command:

• "tcptraceroute" is the command itself and it is used to perform the TCP traceroute.
• "${host}" is a placeholder for the actual hostname or IP address of the destination host you want to trace the route to. It should be replaced with the desired value when running the command.

When executed, the command initiates a series of TCP connection attempts with increasing TTL (Time To Live) values. The TTL value determines the maximum number of hops (network devices) the TCP packet can pass through before being discarded by a network device. Starting with a low TTL value, the command sends TCP packets towards the destination host to identify the path taken.

Each TCP packet contains information about the source and destination. The packet is sent to the first network device (router) in the path, which decrements the TTL by one and forwards the packet to the next hop. If the TTL value becomes zero at any point, the router discards the packet, sending an ICMP (Internet Control Message Protocol) "Time Exceeded" message back to the sender. This way, the traceroute command knows that a router has been reached and identifies its IP address.

The command continues to increase the TTL value, repeating the process until it reaches the destination host. Along the way, it gathers information about each hop, such as the IP address, round-trip time, and any additional information provided by routers. This information is displayed in the terminal as the command runs.

Overall, "tcptraceroute ${host}" helps to determine the network path taken by TCP packets to reach a particular host, providing insights into network routing, potential bottlenecks, and troubleshooting connectivity issues.