Time Server
Check out the code in support/time-server/server.c and support/time-server/client.c.
This is a simple program consisting of a server and a client. The server uses a tcp socket to wait for connections. Once a client has connected, the server will send the current time to it. The client will then print the received time to the console.
Let's build and run this example:
student@os:~/.../support/time-server$ make
gcc -Wall -o server server.c
gcc -Wall -o client client.c
student@os:~/.../support/time-server$ ./server
Then, in another terminal:
student@os:~/.../support/time-server$ ./client 127.0.0.1 2000
The time is Thu Sep 1 11:48:03 2022
Python Version
In support/time-server/python we have the equivalent python implementation for both the server and client:
student@os:~/.../support/time-server/python$ python3 server.py
student@os:~/.../support/time-server/python$ python3 client.py 127.0.0.1 2000
The time is Thu Sep 1 11:58:01 2022
Practice
Try to figure out the protocol used by the server and the client. You can do this by reading the source code, corroborated with information obtained at runtime.
Run the server again (the version in C), but instead of running the client, let's run netcat and pipe the output to hexdump:
nc -d 127.0.0.1 2000 | hexdump -C