Added explanation, installing instructions and demo commands in the

README

README.md

@@ -1 +1,89 @@
 # Netcat eBPF Demo
+
+This is a demo program showcasing a simple eBPF application
+
+## Explanation
+
+This demo shows how simple it is to do content-based redirection in eBPF (which means, directly in the kernel)
+
+For this demo, two eBPF programs will be used:
+
++ one SOCKOPS program, that gets called each time a TCP event happens; this is used to intercept new connections and collect them in a map
++ one SK_SKB verdict program, that analyzes the content of the packets and redirects them to the appropriate socket
+
+The setup is simple: there are two "stable" sockets, one to port 4444 and one to port 5555
+
+Each time a new connection is made on port 3333, the packets of that connection are checked:
+
++ if the message starts with 'a', it will be redirected on the socket to port 4444
++ if the message starts with 'b', it will be redirected on the socket to port 5555
++ otherwise it will not be redirected and it will be sent to the socket on port 3333
+
+All the redirecting is done entirely in the kernel, the userspace program just creates the "stable" connections and keeps them alive
+
+## Installing
+
+To clone it, do
+
+```bash
+git clone https://git.abbiamoundominio.org/palo/Netcat-eBPF-Demo --recurse-submodules
+```
+
+this command will also include the library [liblog](https://github.com/rxi/log.c)
+
+Other dependencies are:
+
++ libbpf
++ bpftool
++ clang+llvm
+
+Just to be sure, on an (up-to-date, so at least kernel 5.18+) Debian/Ubuntu based machine do
+
+```bash
+sudo apt install bptools libbpf-dev netcat clang llvm libelf-dev gcc-multilib build-essential linux-headers-$(uname -r) linux-tools-common linux-tools-generic
+```
+
+To compile, just
+
+```bash
+sudo make -j
+```
+
+This will create a .output directory with all the intermediary files and the main executable, ``netcat_ebpf_demo``
+
+## Demo Commands
+
+Open a terminal and listen on netcat on port 4444:
+
+```bash
+nc -lvp 4444
+```
+
+Then do the same for port 5555:
+
+```bash
+nc -lvp 5555
+```
+
+And for port 3333:
+
+```bash
+nc -lvp 3333
+```
+
+Now, open a fourth terminal and start the program:
+
+```bash
+sudo ./netcat_ebpf_demo
+```
+
+This will open connections to both port 4444 and 5555
+
+
+On a fifth (and final) terminal connect to port 3333:
+
+```bash
+nc 127.0.0.1 3333
+```
+
+In this terminal, try sending some messages: if the message starts with 'a', it will be appear on the terminal with socket 4444; if it starts with 'b', the same but on 5555; otherwise it will go to 3333