SSL certificate for Intranet network

2 minute read

Setup OpenSSL

  1. Download and install OpenSSL from here. For our current task light version is more than enough. I have downloaded this one
  2. Add C:\OpenSSL-Win64\bin to your environment variable PATH
  3. If you face no configuration error when running OpenSSL, then you need to add a new Environment variable: Variable Name - OPENSSL_CONF and Variable Value - C:\OpenSSL-Win64\bin\openssl.cfg

Generate self signed root CA

Generate Root CA Key

Open cmd and cd to the directory you want to save the certificates or from the folder SHITF+RMB and select Open Powershell Windows here. then type -

openssl genrsa -des3 -out myrootca.key 2048

and press ENTER. Type a new Password to protect the key file

Request for certificate

Then create a certificate request using the root CA key file

openssl req -new -key myrootca.key -out myrootca.req

When asked enter the Certificate Authority information that will be shown as Authority that verified the issued certificate.

Self signed the requested certificate

To self sign the request certificate run -

openssl x509 -req -days 7305 -extensions v3_ca -signkey myrootca.key -in myrootca.req -out myrootca.crt

you need to install the .crt file to all of the computer that you want to use varify your issued certificates. When importing .crt certificate make sure you select Place all certificates in the following store and browse to Trusted root certification authorities

Issue Certificate as a CA

We have created our own Certificate Authority in the previous step. Now its time to issue certificate.

Generate Server Key

At first we need to create server key.

openssl genrsa -out myhost.key 2048

Request for certificate

Fill the information for the Server. When asked for CA, give your web server’s IP address or domain name

openssl req -new -key myhost.key -out myhost.req

Issue the Certificate

Create a new file and name it v3.ext in the working directory with the contents. Change the [alt_names] portion as needed.

keyUsage = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment
subjectAltName = @alt_names

DNS.1 = localhost
IP.2 =

after making required changes to the v3.ext file run the command bellow in cmd

openssl x509 -req -days 3650 -CA myrootca.crt -CAkey myrootca.key -CAcreateserial -sha256 -extfile v3.ext -out myhost.crt -in myhost.req

Generate .pfx file for IIS Server

To use the server certificate with IIS server we need .pfx file. To generate .pfx file we need to run-

openssl pkcs12 -export -out myhost.pfx -inkey myhost.key -in myhost.crt

*Verify Certificate Chain

You can verify certificate chain in Windows for debugging purpose by running

certutil -f -urlfetch -verify myhost.crt

Where myhost.crt is the server certificate

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