make-ca is a script to deliver a complete PKI setup for linux workstaitons
and servers using only bash, coreutils, and openssl. It will optionally
generate keystores for OpenJDK and NSS if already installed, using the upstream
Mozilla cacerts.txt or like formatted file. It was originally developed for use
with Linux From Scratch to minimize dependencies for early system build, but
has been written to be generic enough for any Linux distribution.

The make-ca script will process the certificates included in the certdata.txt
file for use in multiple certificate stores (if the associated applications are
present on the system). Additionally, any local certificates stored in
/etc/ssl/local will be imported to the certificate stores. Certificates in this
directory should be stored as PEM encoded OpenSSL trusted certificates.

To create an OpenSSL trusted certificate from a regular PEM encoded file,
provided by a CA not included in Mozilla's certificate distribution, you need
to add trust arguments to the openssl command, and create a new certificate.
There are three trust types that are recognized by the make-ca.sh script,
SSL/TLS, S/Mime, and code signing. For example, using the CAcert root, if you
want it to be trusted for all three roles, the following commands will create
an appropriate OpenSSL trusted certificate:

# install -vdm755 /etc/ssl/local &&
# wget http://www.cacert.org/certs/root.crt &&
# openssl x509 -in root.crt -text -fingerprint -setalias "CAcert Class 1 root" \
          -addtrust serverAuth -addtrust emailProtection -addtrust codeSigning \
          > /etc/ssl/local/CAcert_Class_1_root.pem

If one of the three trust arguments is omitted, the certificate is neither
trusted, nor rejected for that role. Clients that use OpenSSL or NSS
encountering this certificate will present a warning to the user. Clients using
GnuTLS without p11-kit support are not aware of trusted certificates. To
include this CA into the ca-bundle.crt (used for GnuTLS), it must have
serverAuth trust. Additionally, to explicitly disallow a certificate for a
particular use, replace the -addtrust flag with the -addreject flag.

Local trust overrides are handled entirely using the /etc/ssl/local directory.
To override Mozilla's trust values, simple make a copy of the certificate in
the local directory with alternate trust values.