README.md

openssl-demo-server

Example program to implement a TLS server. It was written for demonstration and educational purposes.

Pre-requisites:

• OpenSSL version 1.1.0 or later
• getdns library, for getdns version

Features:

• OCSP stapling
• DNSSEC Authentication chain extension
• session resumption
• 4 x 100 at SSLlabs given the right key and certificate is used
• chroot operation possible
• setuid(non root user) possible

Limitations:

• can't specify to listen in IPv4 only if IPv6 is available
• proxy-mode: destination must be an IPv4 address

Source:

• based on sample code "Simple_TLS_Server" from https://wiki.openssl.org/
• DNSSEC Authentication chain extension based on the implementation of Shumon Huque available at https://github.com/shuque/chainserver
• session resumption worked after I read https://nachtimwald.com/2014/10/05/server-side-session-cache-in-openssl/
• OCSP implementation was copied from nginx

general Build:

$ make
cc -Wall -Wextra -Wpedantic   -c -o main.o main.c
cc -Wall -Wextra -Wpedantic   -c -o ocsp-stapling.o ocsp-stapling.c
cc -Wall -Wextra -Wpedantic   -c -o dnssec-chain-extension.o dnssec-chain-extension.c
cc -Wall -Wextra -Wpedantic  -lssl -lcrypto -lgetdns -o openssl-demo-server main.o ocsp-stapling.o dnssec-chain-extension.o

personal Build:

$ export DEB_BUILD_MAINT_OPTIONS='hardening=+all'
$ export CFLAGS="$( dpkg-buildflags --get CFLAGS ) $( dpkg-buildflags --get CPPFLAGS )"
$ export LDFLAGS="$( dpkg-buildflags --get LDLAGS )"
$ export LIBS='-lssl-dv -lcrypto-dv -lgetdns'
$ make -B

Usage:

# /path/to/openssl-demo-server -h

Usage: openssl-demo-server [options]

  -h                  print this help message
  -sname  <name>      server name               default: dubai.signing-milter.org
  -port   <port>      server port               default: 443
  -cert   <file>      server certificate file   default: ./cert+intermediate.pem
  -key    <file>      server private key file   default: ./key.pem
  -oscp   <file>      server ocsp response file default: ./ocsp.response
  -chroot <dir>       chroot to directory       default: don't chroot
  -user   <name>      switch to that user       default: don't switch user
  -proxy  <ip>:<port> IPv4 address and port to forward to

If the program cannot access the OCSP response file OCSP will be not used.

Bugs:

I'm sure there are some! For that reason: DO NOT USE that software on a production level system!