microps

A learning TCP/IP protocol stack from scratch. This protocol stack was created at KlabExpertCamp6 based on microps.

How to use

Setup

Create a TAP device. In this implementation, microps communicates with the Linux TCP/IP protocol stack by reading and writing to the TAP device.

# microps <-----> TAP (Linux)
# 192.0.2.2/24    192.0.2.1/24
sudo ip tuntap add mode tap user $USER name tap0
sudo ip addr add 192.0.2.1/24 dev tap0
sudo ip link set tap0 up

IP forwarding and NAT are configured to allow microps to communicate with the Internet via Linux.

# microps <-----> TAP (Linux) <-----> Internet
sudo bash -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
sudo iptables -A FORWARD -o tap0 -j ACCEPT
sudo iptables -A FORWARD -i tap0 -j ACCEPT
sudo iptables -t nat -A POSTROUTING -s 192.0.2.0/24 -o <INTERFACE_CONNECTED_TO_INTERNET> -j MASQUERADE

Build & Run

make

wireshark -i tap0
# or
tcpdump -i tap0

Example1: Ping to Google Public DNS (8.8.8.8)

./test/step17.exe

Example2: Echo server

Listen for an incoming connection on port 10007.

nc -nv -l 10007

Connect to nc.

./test/step28.exe

Enter you message on nc.

$ nc -nv -l 10007
Listening on 0.0.0.0 10007
Connection received on 192.0.2.2 7
<YOUR MESSAGE>

LICENSE

MIT

Original Author

YAMAMOTO Masaya