Detailed explanation of the correct way to configure SSL (https certificate) in Apache on Ubuntu

#LoadModule ssl_module modules/mod_ssl.so (If it cannot be found, please confirm whether the openssl plug-in has been compiled)
#Include conf/extra/httpd-ssl.conf

# Add SSL protocol support protocols and remove insecure protocols SSLProtocol all -SSLv2 -SSLv3
# Modify the encryption suite as follows SSLCipherSuite HIGH:!RC4:!MD5:!aNULL:!eNULL:!NULL:!DH:!EDH:!EXP:+MEDIUM
SSLHonorCipherOrder on
# Certificate public key configuration SSLCertificateFile cert/public.pem
# Certificate private key configuration SSLCertificateKeyFile cert/xxxxxxx.key
# Certificate chain configuration. If the attribute starts with a '#' character, please delete it. SSLCertificateChainFile cert/chain.pem

# It is split into several files forming the configuration hierarchy outlined
# below, all located in the /etc/apache2/ directory:
#
# /etc/apache2/
# |-- apache2.conf
# | `-- ports.conf
# |-- mods-enabled
# | |-- *.load
# | `-- *.conf
# |-- conf-enabled
# | `-- *.conf
# `-- sites-enabled
# `-- *.conf
#

<IfModule ssl_module>
 Listen 443
</IfModule>
 
<IfModule mod_gnutls.c>
 Listen 443
</IfModule>

# Depends: setenvif mime socache_shmcb
LoadModule ssl_module /usr/lib/apache2/modules/mod_ssl.so
ssl.conf looks like this:
<IfModule mod_ssl.c>
 
 # Pseudo Random Number Generator (PRNG):
 # Configure one or more sources to seed the PRNG of the SSL library.
 # The seed data should be of good random quality.
 # WARNING! On some platforms /dev/random blocks if not enough entropy
 # is available. This means you then cannot use the /dev/random device
 # because it would lead to very long connection times (as long as
 # it requires to make more entropy available). But usually those
 # platforms additionally provide a /dev/urandom device which doesn't
 # block. So, if available, use this one instead. Read the mod_ssl User
 # Manual for more details.
 #
 SSLRandomSeed startup builtin
 SSLRandomSeed startup file:/dev/urandom 512
 SSLRandomSeed connect builtin
 SSLRandomSeed connect file:/dev/urandom 512
 
 ##
 ## SSL Global Context
 ##
 ## All SSL configuration in this context applies both to
 ## the main server and all SSL-enabled virtual hosts.
 ##
 
 #
 # Some MIME-types for downloading Certificates and CRLs
 #
 AddType application/x-x509-ca-cert .crt
 AddType application/x-pkcs7-crl .crl
 
 # Pass Phrase Dialog:
 # Configure the pass phrase gathering process.
 # The filtering dialog program (`builtin' is an internal
 # terminal dialog) has to provide the pass phrase on stdout.
 SSLPassPhraseDialog exec:/usr/share/apache2/ask-for-passphrase
 
 # Inter-Process Session Cache:
 # Configure the SSL Session Cache: First the mechanism 
 # to use and second the expiring timeout (in seconds).
 # (The mechanism dbm has known memory leaks and should not be used).
 #SSLSessionCache dbm:${APACHE_RUN_DIR}/ssl_scache
 SSLSessionCache shmcb:${APACHE_RUN_DIR}/ssl_scache(512000)
 SSLSessionCacheTimeout 300
 
 # Semaphore:
 # Configure the path to the mutual exclusion semaphore the
 # SSL engine uses internally for inter-process synchronization. 
 # (Disabled by default, the global Mutex directive consolidates by default
 # this)
 #Mutex file:${APACHE_LOCK_DIR}/ssl_mutex ssl-cache
 
 
 # SSL Cipher Suite:
 # List the ciphers that the client is permitted to negotiate. See the
 # ciphers(1) man page from the openssl package for list of all available
 # options.
 # Enable only secure ciphers:
 SSLCipherSuite HIGH:!RC4:!MD5:!aNULL:!eNULL:!NULL:!DH:!EDH:!EXP:+MEDIUM
 
 # SSL server cipher order preference:
 # Use server priorities for cipher algorithm choice.
 # Clients may prefer lower grade encryption. You should enable this
 # option if you want to enforce stronger encryption, and can afford
 # the CPU cost, and did not override SSLCipherSuite in a way that puts
 # insecure ciphers first.
 # Default: Off
 SSLHonorCipherOrder on
 
 # The protocols to enable.
 # Available values: all, SSLv3, TLSv1, TLSv1.1, TLSv1.2
 # SSL v2 is no longer supported
 SSLProtocol all -SSLv2 -SSLv3
 
 # Allow insecure renegotiation with clients which do not yet support the
 # secure renegotiation protocol. Default: Off
 #SSLInsecureRenegotiation on
 
 # Whether to forbid non-SNI clients to access name based virtual hosts.
 # Default: Off
 #SSLStrictSNIVHostCheck On
 
</IfModule>
 
# vim: syntax=apache ts=4 sw=4 sts=4 sr noet

<IfModule mod_ssl.c>
 <VirtualHost _default_:443>
 ServerName 
 
 ################Add your own site configuration##########
 
 
 
 # Available loglevels: trace8, ..., trace1, debug, info, notice, warn,
 # error, crit, alert, emerg.
 # It is also possible to configure the loglevel for particular
 # modules, e.g.
 #LogLevel info ssl:warn
 
 ErrorLog ${APACHE_LOG_DIR}/error.log
 CustomLog ${APACHE_LOG_DIR}/access.log combined
 
 # For most configuration files from conf-available/, which are
 # enabled or disabled at a global level, it is possible to
 # include a line for only one particular virtual host. For example the
 # The following line enables the CGI configuration for this host only
 # after it has been globally disabled with "a2disconf".
 #Include conf-available/serve-cgi-bin.conf
 
 # SSL Engine Switch:
 # Enable/Disable SSL for this virtual host.
 SSLEngine on
 
 # A self-signed (snakeoil) certificate can be created by installing
 # the ssl-cert package. See
 # /usr/share/doc/apache2/README.Debian.gz for more info.
 # If both key and certificate are stored in the same file, only the
 # SSLCertificateFile directive is needed.
 SSLCertificateFile /etc/apache2/cert/public.pem
 SSLCertificateKeyFile /etc/apache2/cert/xxxxxxx.key
 
 # Server Certificate Chain:
 # Point SSLCertificateChainFile at a file containing the
 # concatenation of PEM encoded CA certificates which form the
 # certificate chain for the server certificate. Alternatively
 # the referenced file can be the same as SSLCertificateFile
 # when the CA certificates are directly appended to the server
 # certificate for convinience.
 SSLCertificateChainFile /etc/apache2/cert/chain.pem
 
 # Certificate Authority (CA):
 # Set the CA certificate verification path where to find CA
 # certificates for client authentication or alternatively one
 # huge file containing all of them (file must be PEM encoded)
 # Note: Inside SSLCACertificatePath you need hash symlinks
 # to point to the certificate files. Use the provided
 # Makefile to update the hash symlinks after changes.
 #SSLCACertificatePath /etc/ssl/certs/
 #SSLCACertificateFile /etc/apache2/ssl.crt/ca-bundle.crt
 
 # Certificate Revocation Lists (CRL):
 # Set the CA revocation path where to find CA CRLs for client
 # authentication or alternatively one huge file containing all
 # of them (file must be PEM encoded)
 # Note: Inside SSLCARevocationPath you need hash symlinks
 # to point to the certificate files. Use the provided
 # Makefile to update the hash symlinks after changes.
 #SSLCARevocationPath /etc/apache2/ssl.crl/
 #SSLCARevocationFile /etc/apache2/ssl.crl/ca-bundle.crl
 
 # Client Authentication (Type):
 # Client certificate verification type and depth. Types are
 # none, optional, require and optional_no_ca. Depth is a
 # number which specifies how deeply to verify the certificate
 # issuer chain before deciding the certificate is not valid.
 #SSLVerifyClient require
 #SSLVerifyDepth 10
 
 # SSL Engine Options:
 # Set various options for the SSL engine.
 # o FakeBasicAuth:
 # Translate the client X.509 into a Basic Authorisation. This means that
 # the standard Auth/DBMAuth methods can be used for access control.
 # user name is the `one line' version of the client's X.509 certificate.
 # Note that no password is obtained from the user. Every entry in the user
 # file needs this password: `xxj31ZMTZzkVA'.
 # o ExportCertData:
 # This exports two additional environment variables: SSL_CLIENT_CERT and
 # SSL_SERVER_CERT. These contain the PEM-encoded certificates of the
 # server (always existing) and the client (only existing when client
 # authentication is used). This can be used to import the certificates
 # into CGI scripts.
 # o StdEnvVars:
 # This exports the standard SSL/TLS related `SSL_*' environment variables.
 # Per default this exportation is switched off for performance reasons,
 # because the extraction step is an expensive operation and is usually
 # useless for serving static content. So one usually enables the
 # exportation for CGI and SSI requests only.
 # o OptRenegotiate:
 # This enables optimized SSL connection renegotiation handling when SSL
 # directives are used in per-directory context.
 #SSLOptions +FakeBasicAuth +ExportCertData +StrictRequire
 <FilesMatch "\.(cgi|shtml|phtml|php)$">
 SSLOptions +StdEnvVars
 </FilesMatch>
 <Directory /usr/lib/cgi-bin>
 SSLOptions +StdEnvVars
 </Directory>
 
 # SSL Protocol Adjustments:
 # The safe and default but still SSL/TLS standard compliant shutdown
 # approach is that mod_ssl sends the close notify alert but doesn't wait for
 # the close notify alert from client. When you need a different shutdown
 # approach you can use one of the following variables:
 # o ssl-unclean-shutdown:
 # This forces an unclean shutdown when the connection is closed, ie no
 # SSL close notify alert is sent or allowed to be received. This violates
 # the SSL/TLS standard but is needed for some brain-dead browsers. Use
 # this when you receive I/O errors because of the standard approach where
 # mod_ssl sends the close notify alert.
 # o ssl-accurate-shutdown:
 # This forces an accurate shutdown when the connection is closed, ie a
 # SSL close notify alert is sent and mod_ssl waits for the close notify
 # alert of the client. This is 100% SSL/TLS standard compliant, but in
 # practice often causes hanging connections with brain-dead browsers. Use
 # this only for browsers where you know that their SSL implementation
 # works correctly.
 # Notice: Most problems of broken clients are also related to the HTTP
 # keep-alive facility, so you usually additionally want to disable
 # keep-alive for those clients, too. Use variable "nokeepalive" for this.
 # Similarly, one has to force some clients to use HTTP/1.0 to workaround
 # their broken HTTP/1.1 implementation. Use variables "downgrade-1.0" and
 # "force-response-1.0" for this.
 # BrowserMatch "MSIE [2-6]" \
 # nokeepalive ssl-unclean-shutdown \
 # downgrade-1.0 force-response-1.0
 
 </VirtualHost>
</IfModule>
 
# vim: syntax=apache ts=4 sw=4 sts=4 sr noet