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How do I configure a CA and sign certificates using OpenSSL in Red Hat and Oracle LINUX

1. Set up /etc/pki/CA as your certificate authority’s working directory. To do this, open /etc/pki/tls/openssl.cnf in a text editor. Find the section labelled “[CA_default]”, and edit the following lines in the section to read:

dir = /etc/pki/CA
certificate = $dir/my-ca.crt
crl = $dir/my-ca.crl
private_key = $dir/private/my-ca.key

2. Edit the [policy_match] section of /etc/pki/tls/openssl.cnf

countryName= optional
stateOrProvinceName= optional
organizationName= optional
organizationalUnitName= optional
commonName= supplied
emailAddress= optional

3. Edit the “[req_distinguished_name]” section to fit your needs

countryName_default =US
stateOrProvinceName_default = Pensylvannia
localityName_default = Wallingford
organizationName_default = WMD LLC.

4. Create the following directories if missing

# mkdir /etc/pki/CA/{certs,crl,newcerts}

5. Create an empty certificate index:

# touch /etc/pki/CA/index.txt

6. Create a file to indicate the next certificate serial number to be issued:

# echo 01 > /etc/pki/CA/serial

7. While in /etc/pki/CA, you need to generate a private key and a self-signed CA certificate. You will be prompted for a passphrase, which will be needed later:

# (umask 077; openssl genrsa -out private/my-ca.key -des3 2048)

8. For your CA certificate, take the defaults for CountryName, StateOrProvinceName, LocalityName, and Organization, and for CommonName use”$hostname Certificate Authority”. Set the other fields as you see fit:

# openssl req -new -x509 -key private/my-ca.key -days 1000 > my-ca.crt

The /etc/pki/CA/private/my-ca.key file is the private key for your CA. This file must be very carefully protected. The my-ca.crt file is the public CA certificate that will eventually be distributed to your users.

9. Let’s assume that we need to sign a server certificate of our LDAP host. Create a private key for the service on the appropriate LDAP host and copy it to the CA host.

#  openssl genrsa 1024 > ldap_server.key

10. Back to the CA host – use the openssl command to sign the copied LDAP host certificate.

# openssl ca -config /etc/pki/tls/openssl.cnf -out ldap_server.crt -infiles ldap_server.key

11. Install the ldap_server.crt on the appropriate host

Posted in LINUX.

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