How To Create A SSL Self-Signed Certificate, One-Liner

You'll need to change the values inside the -subj variable to suit your needs.

/usr/bin/openssl req -x509 -newkey rsa:2048 -keyout server.key -out server.cert -days 365 -nodes -subj "/C=$countryCode/ST=$state/L=$location/O=$organization/OU=$orgUnit/CN=$hostname"

Just a note, on 32-bit systems, OpenSSLs' use of time_t routine to calculate the epoch is limited to the year 2038 so your -days variable cannot exceed this date or the cert expiration will roll back in time and already be expired. 64-bit systems are not hindered with this limitation.

Verify SSL Certificate And CSR Match

openssl x509 -noout -modulus -in server.crt | openssl md5
openssl req -noout -modulus -in server.csr | openssl md5

Verify SSL Private Key And Certificate Match

openssl x509 -noout -modulus -in server.crt | openssl md5
openssl rsa -noout -modulus -in server.key | openssl md5

Verify SSL Private Key And CSR Match

Compare the output from the following:

openssl rsa -noout -modulus -in server.key | openssl md5 
openssl req -noout -modulus -in server.csr | openssl md5

This can also be accomplished in PHP using:

<php
//CERTIFICATE INFORMATION 
$dn = array( 
  "countryName" => $countryName, 
  "stateOrProvinceName" => $stateOrProvinceName, 
  "localityName" => $localityName, 
  "organizationName" => $organizationName, 
  "organizationalUnitName" => $organizationalUnitName, 
  "commonName" => $commonName, 
  "emailAddress" => $emailAddress 
); 

//GENERATE NEW PRIVATE KEY
$priv = openssl_pkey_new(); 

//GENERATE CSR
$csr = openssl_csr_new($dn, $priv); 

//LOAD DETAILS
$privDetails = openssl_pkey_get_details($priv); 
$csrDetails = openssl_pkey_get_details(openssl_csr_get_public_key($csr)); 

//OUTPUT
echo md5($privDetails['rsa']['n']); 
echo md5($csrDetails['rsa']['n']); 
?>

How To Create A SSL Self-Signed Certificate

openssl genrsa -out ca.key 2048 
openssl req -new -key ca.key -out ca.csr
openssl x509 -req -days 365 -in ca.csr -signkey ca.key -out ca.crt

How To Create A SSL CSR Certificate Signing Request

openssl genrsa -out ca.key 2048 
openssl req -new -key ca.key -out ca.csr

How To Create A SSL Private Key

openssl genrsa -out ca.key 2048 

SSL Certificate Directory Location On cPanel

/etc/ssl/certs