INTRODUCTION

lwIP is a small independent implementation of the TCP/IP protocol suite. (https://savannah.nongnu.org/projects/lwip/)

lwIP supports TLS basing on mbedtls. (https://www.trustedfirmware.org/projects/mbed-tls/)

This project integrates OpenSSL into lwIP.

HOW TO USE

Tested on CentOS 8

1. Install OpenSSL

yum install openssl openssl-devel

2. Create tap interface and net bridge.

ip tuntap add dev tap0 mode tap
ip link set tap0 up
brctl addbr lwipbridge
brctl addbr lwipbridge
brctl addif lwipbridge tap0
ip addr add 192.168.1.1/24 dev lwipbridge
ip link set dev lwipbridge up

3. Start an HTTPS server (e.g. Nginx) and listen on port 443.

4. Compile and run.

cd lwip
cp ./contrib/examples/example_app/lwipcfg.h.example ./contrib/examples/example_app/lwipcfg.h

# Uncomment "#define USE_DHCP 0" and "#define USE_AUTOIP 0", and set LWIP_OPENSSL_EXAMPLES_APP to 1
vim ./contrib/examples/example_app/lwipcfg.h

cd ./contrib/ports/unix/example_app/
mkdir build && cd build
cmake -DLWIP_DIR=../../../.. ..
make

# Run the test app
./example_app

When you run example_app, it will send an HTTPs request "GET /" to 192.168.1.1:443 (which is the IP of lwipbridge), and read the response then print it.

It also starts an HTTPs server listening on 192.168.1.200:443, and you can do "curl -k -v https://192.168.1.200/".