PHP OpenSSL extension has a package?

I know that OpenSSL extension is in PHP source, but I can't enable it when I perform apt-get install php5. There is not even a apt-get install php5-openssl. How I must proceed?

I think SSL support doesn't depend on an extension, it's already built into Ubuntu's PHP. Try creating a PHP file in your web server with this content:

<?php phpinfo() ?>

then access it in a browser (http://<server>/<file>.php). You should see:

and

I have only these PHP packages installed: libapache2-mod-php5, php5-cli, php5-common, php5-gd, php5-mcrypt, php5-mysql.

Try:

php -i | grep -i openssl

If you have the OpenSSL extension installed, you should see something like this:

openssl
OpenSSL support => enabled
OpenSSL Library Version => OpenSSL 1.0.1f 6 Jan 2014
OpenSSL Header Version => OpenSSL 1.0.1f 6 Jan 2014
openssl.cafile => no value => no value
openssl.capath => no value => no value
OpenSSL support => enabled

It seems that the OpenSSL extension is installed by default.

Update:

If you don't have this extension, you can edit php.ini file.

From php.ini:

;;;;;;;;;;;;;;;;;;;;;;
; Dynamic Extensions ;
;;;;;;;;;;;;;;;;;;;;;;

; If you wish to have an extension loaded automatically, use the following
; syntax:
;
;   extension=modulename.extension
;
; For example, on Windows:
;
;   extension=msql.dll
;
; ... or under UNIX:
;
;   extension=msql.so
;
; ... or with a path:
;
;   extension=/path/to/extension/msql.so
;
; If you only provide the name of the extension, PHP will look for it in its
; default extension directory.
;