OpenSSL Generating a Certificate Signing Request

Generate the Certificate Signing Request (CSR)

Apache with mod_ssl Enabled (No subjectAltName)

1. If required follow the OpenSSL Generating a Private Key procedure.
2. For Apache purposes, use the key with no pass phrase to generate the CSR file.
3. Generate the CSR from the private key using openssl.

   # openssl req -new -key <key_name>.key -out <csr_name>.csr

4. Enter the information as required by the prompts.
5. Verify the checksum of the key matches the checksum CSR.

   # openssl req -noout -modulus -in <csr_name>.csr | openssl md5

Apache with mod_ssl Enabled (With subjectAltName)

1. If required follow the OpenSSL Generating a Private Key procedure.
2. For Apache purposes, use the key with no pass phrase to generate the CSR file.
3. Create a config file to be configured with the multiple subdomains.

   # cat << EOL >> <config_file>.cnf

[ req ] 
default_bits       = 2048 
default_keyfile    = <private_key>.key 
distinguished_name = req_distinguished_name 
req_extensions     = req_ext 

[ req_distinguished_name ] 
countryName                 = Country Name (2 letter code) 
countryName_default         = US 
stateOrProvinceName         = State or Province Name (full name) 
stateOrProvinceName_default = New York 
localityName                = Locality Name (eg, city) 
localityName_default        = New York 
organizationName            = Organization Name (eg, company) 
organizationName_default    = Example 
commonName                  = Common Name (e.g. server FQDN or YOUR name) 
commonName_max              = 64 

[ req_ext ] 
subjectAltName = @alt_names 

[alt_names] 
DNS.1   = <domain>.com 
DNS.2   = www.<domain>.com 
DNS.3   = *.<domain>.com 
EOL 

1. Generate the CSR from the private key using openssl.

   # openssl req -new -key <key_name>.key -out <csr_name>.csr

2. Enter the information as required by the prompts.
3. Verify the checksum of the key matches the checksum CSR.

   # openssl req -noout -modulus -in <csr_name>.csr | openssl md5

Further Reading

1. How to Generate SSL key, CSR, and Self Signed Certificate for Apache