SSL in a development environment

Using ssl certificates can be a tedious task. Especially in a development or testing environment where you (or your company) does not want to pay for expensive certificates. More importantly, you do not have to pay for certificates in a dev/test environment assuming that everyone accessing that environment is within your control. In these cases self signed certificates allow you to achieve the same effect as if you were using a signed certificate.

Generate a self signed (root) certificate

You can use the following script to generate a ssl certificate (I took most of the information from here). I saved the following code to a file called sslcertgen and saved it in /usr/local/bin or anywhere else on my system’s $PATH.

# Create a self signed (wildcard) certificate


if [[ "" == "$1" || "help" == "$1" ]]; then
  echo "Usage: $(basename $0) certificate_name"
  exit 3


openssl genrsa $RSA_ENC > "${KEY}"
openssl req -new -x509 -nodes -sha1 -days ${DAYS} -extensions v3_ca -key "${KEY}" > "${CRT}"
openssl pkcs12 -export -out ${PFX} -inkey ${KEY} -in ${CRT} -certfile ${CRT}

cat "${CRT}" "${KEY}" > "${PEM}"

chmod 400 "${KEY}" "${PEM}" "${PFX}"
chmod 644 "${CRT}"

Now I can use this script to create a wildcard certificate for e.g. like this:

# Generate a certificate named mywebsite
$ sslcertgen mywebsite
# ...[enter as the Common Name]...

If you use * as the common name you will create a self signed wild card certificate.

This will producte the files:

  • mywebsite.crt contains the public version of this ssl key. This is what you install on clients;
  • mywebsite.key contains the private version of this ssl certificate. You keep this private and use this on the server;
  • mywebsite.pem contains the private and public key concatenaded together. This is often used by apache.
  • mywebsite.pfx contains the private and public key in a format compatible for IIS based servers.

From the above files the most important (and the only two essentials ones) are the .crt and the .key file. If you need to convert the sertificate to other formats, read this article

Server: Install the SSL certificate on the server

Place the .crt and the .key files somewhere where your nginx application can access them. For enhanced security make sure that the .key file has only read permissions for the user that nginx is running as. Now that we have generated an ssl certificate we can ‘install’ it on the server. There are many different ways to do this and it really depends on the application you are using. In the below example I will show you how to configure nginx:

server {
  listen       443;

  ssl                  on;
  ssl_certificate      /etc/server_certs/mywebsite.crt;
  ssl_certificate_key  /etc/server_certs/mywebsite.key;

  location / {

Restart nginx using sudo service nginx restart on Debian based distributions. Now when you visit you will get a certificate warning. The reason for this is simple. We created a self signed certificate. It was not signed by a central authority. Because of this clients are not able to tell if they can trust this certificate or not. To make sure that clients trust the connection we have to explicitly tell them that it is trustable by adding the .crt version of the certificate to the local certificate store.

I will explain how to do this on Debian based systems in the next part.

Client: Install a self signed SSL (root) certificate on a Unix client

So the server is set up and accessible using an ssl connection. To tell the client that the self signed certificate from the server is trustable we will download the public version and ‘install’ it locally.

First download the certificate from the server:

# Download a SSL certificate from a remote host
$ openssl s_client -connect -showcerts < /dev/null 2> /dev/null | sed -n '/BEGIN CERTIFICATE/,/END CERTIFICATE/p' > mywebsite.crt

Or copy the .crt file we generated earlier with ssh to the client. Now that we have the public version available we can ‘install’ it.

# Copy the certificate to the ca-certifactes directory
cp mywebsite.crt /usr/share/ca-certificates
chmod 644 /usr/share/ca-certificates/certificate.crt

Edit this file and add mywebsite.crt on a blank line to the end

# Note that the path is relative to the directory /usr/share/ca-certificates
$ vim /etc/ca-certificates.conf

Now update the certificate database

# Update the local CA certificate database

That’s it. now we told the client to trust this self signed certificate by installing it locally.

# Test if it works now
wget -O- ""

# Testing if SSL works
openssl s_client -connect -state -debug < /dev/null

Server: Install .pfx certificate in IIS 6.0 on Windows Server 2003

The following walkthrough describes how to add a .pfx formatted self signed certificate to an IIS application on Windows 2003. Look for more information about viewing certificates with the Snap-In tool here.

# Go to 'Start' -> 'Run' and type: mmc <enter>
# Go to 'File' -> 'Add/Remove Snap-in'
# Click 'Add'
# Select 'Certificates'
# Click 'Add', Click 'Close', Click 'Ok'
# Right click 'Trusted Root Certification Authorities' -> 'All Tasks' -> 'Import'
# Import the created .pfx certificate
# Next -> Next -> Next -> Ok
# Copy the certificate from 'Trusted Root...' to 'Personal' folder.
# Close mmc
# Configure IIS 6.0 to use server ssl certificate
# Restart IIS