TCP "ping" for connection debugging

Question

We have a rather complex network setup, and in order to debug a non-working connection to a remote port 80/tcp I want to send a continuous stream of TCP packets (basically like ping is continuously sending ICMP packets), so that we can find at which hop the packets are dropped.

Of course I could wrap netcat in a loop, but that would be rather inconvenient. Is there a better way?

Answer 1

What you're asking can be accomplished with hping3.

hping3 -S -p 80 192.168.23.42

-S tells the command to send TCP SYN packets, so that each packet is a new connection attempt and doesn't get dismissed as "unrelated to an existing TCP connection."

-p 80 tells the command to connect to port 80 on the remote host (192.168.23.42, replace the address with your actual host).

You can add -i NUM to wait NUM seconds between each packet.