This is a simple multithreaded web server I made which simply returns the client's IP address. It currently only works on IPv4.
After running the server, you can connect to it at http://127.0.0.1:8080. If it were an IPv6 server, you could connect to it at http://[::1]:8080. You can specify a different listening port as a command line argument passed to the server, e.g. ./server 10023. Only port numbers greater than 9999 are accepted.
Note: the threading (where applicable) used in these files is extremely basic. A real web server would use a thread pool.
Another thing to note is that a real web server would need to validate each HTTP request it receives.
Side note: sending ICMP packets requires raw sockets, which is limited to users with root privileges.