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Generate ssl certificates with Subject Alt Names

Generate ssl certificates with Subject Alt Names on OSX

Open ssl.conf in a text editor.

Edit the domain(s) listed under the [alt_names] section so that they match the local domain name you want to use for your project, e.g.

DNS.1   = my-project.dev

Additional FQDNs can be added if required:

DNS.1   = my-project.dev
DNS.2   = www.my-project.dev
DNS.3   = fr.my-project.dev

Create a directory for your project, e.g. my_project and save ssl.conf inside it.

Open Terminal and navigate to 'my_project':

cd my_project

Generate a private key:

openssl genrsa -out private.key 4096

Generate a Certificate Signing Request

openssl req -new -sha256 \
    -out private.csr \
    -key private.key \
    -config ssl.conf 

(You will be asked a series of questions about your certificate. Answer however you like, but for 'Common name' enter the name of your project, e.g. my_project)

Now check the CSR:

openssl req -text -noout -in private.csr

You should see this:

X509v3 Subject Alternative Name: DNS:my-project.site and Signature Algorithm: sha256WithRSAEncryption

Generate the certificate

openssl x509 -req \
    -sha256 \
    -days 3650 \
    -in private.csr \
    -signkey private.key \
    -out private.crt \
    -extensions req_ext \
    -extfile ssl.conf

Add the certificate to keychain and trust it:

sudo security add-trusted-cert -d -r trustRoot -k /Library/Keychains/System.keychain private.crt

(Alternatively, double click on the certificate file private.crt to open Keychain Access. Your project name my_project will be listed under the login keychain. Double click it and select 'Always trust' under the 'Trust' section.)

If you are using MAMP Pro, add (or edit) a host with the server name you listed under the [alt_names] section of your ssl.conf. On the SSL tab select the Certificate file and Certificate key that you just generated.

Save changes and restart Apache.

[ req ]
default_bits = 4096
distinguished_name = req_distinguished_name
req_extensions = req_ext
[ req_distinguished_name ]
countryName = Country Name (2 letter code)
countryName_default = GB
stateOrProvinceName = State or Province Name (full name)
stateOrProvinceName_default = England
localityName = Locality Name (eg, city)
localityName_default = Brighton
organizationName = Organization Name (eg, company)
organizationName_default = Hallmarkdesign
commonName = Common Name (e.g. server FQDN or YOUR name)
commonName_max = 64
commonName_default = localhost
[ req_ext ]
subjectAltName = @alt_names
[alt_names]
DNS.1 = your-website.dev
DNS.2 = another-website.dev
@johnclary

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commented Feb 21, 2018

This was tremendously helpful--thanks!

@benjibee

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commented Mar 2, 2018

This has been working great for my local development setup until a recent PHP-built project. It uses file_get_contents() and I've started getting this PHP error which seems to have 100+ fixes, but I have a feeling it's something to do with these certs not being properly registered:


file_get_contents(): SSL operation failed with code 1. OpenSSL Error messages:
error:14090086:SSL routines:ssl3_get_server_certificate:certificate verify failed in: [path to PHP file]

😢

@friendscottn

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commented Mar 26, 2018

THANK YOU!

@michael-pratt

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commented May 11, 2018

Many thanks! I couldn't figure out why my SANs weren't carrying over from the CSR to the final cert. This was a big help!

@mcolacino

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commented Jul 10, 2018

THANKS A LOT MAN!

@Zextremo

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commented Aug 21, 2018

THANKS

@pserrano

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commented Sep 18, 2018

i would also add to ssl.conf

organizationalUnitName          = Organizational Unit Name (eg, section)
organizationalUnitName_default    = IT
@jorgejesus

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commented Jan 31, 2019

Your ssl.conf help me alot !!!

@boh717

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commented Mar 8, 2019

Thanks, it worked like a charm!

Would you please add -sha256 option to the signing process?

openssl x509 -req \
    -sha256 \
    -days 3650 \
    -in private.csr \
    -signkey private.key \
    -out private.crt \
    -extensions req_ext \
    -extfile ssl.conf

Without that option, certificate will be signed with SHA1 (which is deprecated).

@shikaku

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commented Mar 13, 2019

Thanks, very helpful!

@carlosyague

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commented Jun 3, 2019

Thank you so much @croxton!!

@alexwitedja

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commented Jun 30, 2019

I'm getting error
NET::ERR_CERT_AUTHORITY_INVALID

How do i do this sudo security add-trusted-cert -d -r trustRoot -k /Library/Keychains/System.keychain private.crt in windows?

@Trollazzo

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commented Jul 30, 2019

Thank you for this marvelous work

@amnkh

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commented Sep 4, 2019

i would also add to ssl.conf

organizationalUnitName          = Organizational Unit Name (eg, section)
organizationalUnitName_default    = IT

Thanks @croxton and @pserrano,
I added organizationalUnitName, emailAddress and different SAN examples to make Wildcard usage more clear.

[ req ]
default_bits       = 4096
distinguished_name = req_distinguished_name
req_extensions     = req_extensions_section
prompt = yes

[ req_distinguished_name ]
countryName                     = Country Name (2 letter code)
countryName_min                 = 2
countryName_max                 = 2
countryName_default             = GB
stateOrProvinceName             = State or Province Name (full name)
stateOrProvinceName_default     = England
localityName                    = Locality Name (eg, city)
localityName_default            = Brighton
organizationName                = Organization Name (eg, company)
organizationName_default        = Hallmarkdesign
organizationalUnitName          = Organizational Unit Name (eg, section)
organizationalUnitName_default  = IT
commonName                      = Common Name (eg, server FQDN or YOUR name)
commonName_max                  = 64
commonName_default              = example.com
emailAddress                    = Email Address (eg, admin@example.com)
emailAddress_max                = 64
emailAddress_default            = info@example.com

[ req_extensions_section ]
subjectAltName = @subject_alternative_name_section

[ subject_alternative_name_section ]
DNS.1   = subdomain.example.com
DNS.2   = *.example.com
DNS.3   = www.example.org
DNS.4   = *.example.org

Result:

Subject: C = GB, ST = England, L = Brighton, O = Hallmarkdesign, OU = IT, CN = example.com, emailAddress = info@example.com
Requested Extensions:
            X509v3 Subject Alternative Name:
                DNS:subdomain.example.com, DNS:*.example.com, DNS:www.example.org, DNS:*.example.org
@HighSoftWare96

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commented Sep 13, 2019

SUPER-useful!

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