This repository contains a TLS server and TLS client written in C for demonstration purposes.

You need to have libssl1.0 and libssl1.0-dev (or a later version) installed.

gcc -o build/client client.c -I /usr/include/openssl/ -lssl -lcrypto
gcc -o build/server server.c -I /usr/include/openssl/ -lssl -lcrypto

To create X509 certificates (hit Enter 7 times after starting this):

openssl req -x509 -newkey rsa:2048 -keyout key.pem -out cert.pem -days 365

Start the server:

build/server

Start the client:

build/client

See also:

• https://wiki.openssl.org/index.php/Simple_TLS_Server
• https://wiki.openssl.org/index.php/SSL/TLS_Client

Check the server by running testssl.sh, easiest in docker (replace IP, if needed):

docker run --rm -ti drwetter/testssl.sh 10.200.0.1:4433