How to create a self-signed SSL Certificate with SubjectAltName(SAN)

After Chrome 58, self-signed certificate without SAN is not valid anymore.

Step 1: Generate a Private Key

openssl genrsa -out example.com.key 2048

Step 2: Generate a CSR (Certificate Signing Request)

openssl req -new -key example.com.key -out example.com.csr

Enter pass phrase for example.com.key:
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [XX]:XX
State or Province Name (full name) []:State
Locality Name (eg, city) [Default City]:City
Organization Name (eg, company) [Default Company Ltd]:Company
Organizational Unit Name (eg, section) []:BU
Common Name (eg, your name or your server's hostname) []:*.example.com
Email Address []:[email protected]

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:

Step 3: Create config file for SAN

touch v3.ext

File content

subjectKeyIdentifier   = hash
authorityKeyIdentifier = keyid:always,issuer:always
basicConstraints       = CA:TRUE
keyUsage               = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment, keyAgreement, keyCertSign
subjectAltName         = DNS:example.com, DNS:*.example.com
issuerAltName          = issuer:copy

Step 5: Generating a Self-Signed Certificate

openssl x509 -req -in example.com.csr -signkey example.com.key -out example.com.crt -days 3650 -sha256 -extfile v3.ext

blissini/Self-Signed SSL with SAN.md

How to create a self-signed SSL Certificate with SubjectAltName(SAN)

Step 1: Generate a Private Key

Step 2: Generate a CSR (Certificate Signing Request)

Step 3: Create config file for SAN

Step 5: Generating a Self-Signed Certificate

Reference