Overview#

Obtain a Certificate from Server#

You can Obtain a Certificate from Server with OpenSSL

Obtain Subject Alternative Name#

We found we often needed to verify the Subject Alternative Name of Certificates when doing installs and validations. Bouncing around in Imanager or other tools took too long and we came up with this.
openssl s_client -connect ldap.willeke.com:636 | openssl x509 -noout -text | egrep -A 1 'X509v3 Subject Alternative Name:'
depth=1 O = UNIXAUTH, OU = Organizational CA
verify error:num=19:self signed certificate in certificate chain
verify return:0
            X509v3 Subject Alternative Name:
                IP Address:10.220.180.80, IP Address:10.220.180.81, IP Address:10.220.21.19, DNS:ldap.willeke.com

General OpenSSL Commands#

These commands allow you to generate CSRs, Certificates, Private Keys and do other miscellaneous tasks.

Generate a new private key and Certificate Signing Request#

openssl req -out CSR.csr -new -newkey rsa:2048 -nodes -keyout privateKey.key

Generate a self-signed certificate (see How to Create and Install an Apache Self Signed Certificate for more info)#

openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout privateKey.key -out certificate.crt

Generate a certificate signing request (CSR) for an existing private key#

openssl req -out CSR.csr -key privateKey.key -new

Generate a certificate signing request based on an existing certificate#

openssl x509 -x509toreq -in certificate.crt -out CSR.csr -signkey privateKey.key

Remove a passphrase from a private key#

openssl rsa -in privateKey.pem -out newPrivateKey.pem

Checking Using OpenSSL#

If you need to check the information within a Certificate, CSR or Private Key, use these commands. You can also check CSRs and check certificates using our online tools.

Check a Certificate Signing Request (CSR)#

openssl req -text -noout -verify -in CSR.csr

Check a private key#

openssl rsa -in privateKey.key -check

Check a certificate#

openssl x509 -in certificate.crt -text -noout

Check a PKCS#12 file (.pfx or .p12)#

openssl pkcs12 -info -in keyStore.p12

Debugging Using OpenSSL#

If you are receiving an error that the private doesn't match the certificate or that a certificate that you installed to a site is not trusted, try one of these commands. If you are trying to verify that an SSL certificate is installed correctly, be sure to check out the SSL Checker.

Check an MD5 hash of the public key to ensure that it matches with what is in a CSR or private key#

openssl x509 -noout -modulus -in certificate.crt | openssl md5

or 

openssl rsa -noout -modulus -in privateKey.key | openssl md5

or

openssl req -noout -modulus -in CSR.csr | openssl md5

Check an SSL connection. All the certificates (including Intermediates) should be displayed#

openssl s_client -connect www.paypal.com:443

Converting Certificate Formats#

These commands allow you to Converting Certificate Formats and keys to different formats to make them compatible with specific types of servers or software. For example, you can convert a normal PEM file that would work with Apache to a PFX (PKCS#12) file and use it with Tomcat or IIS. Use our SSL Converter to convert certificates without messing with OpenSSL.

More Information#

There might be more information for this subject on one of the following:

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« This page (revision-5) was last changed on 17-May-2016 11:08 by jim