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Created October 14, 2017 13:12
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Create self-signed SSL certificate with SubjectAltName(SAN)

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 -des3 -out 2048

Step 2: Generate a CSR (Certificate Signing Request)

openssl req -new -key -out
Enter pass phrase for
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) []:*
Email Address []

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

Step 3: Remove Passphrase from Key

openssl rsa -in -out

Step 4: 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:*
issuerAltName          = issuer:copy

Step 5: Generating a Self-Signed Certificate

openssl x509 -req -in -signkey -out -days 3650 -sha256 -extfile v3.ext


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Your best bet is to create a CA - and then use that to sign the CSR as above. Good luck!
Hi, can you give instructions on how to actually do this! I'm new to this and need to do this at the moment!

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