Add short overview, move header files section further down.

=head1 SYNOPSIS

=head1 DESCRIPTION

=head1 OVERVIEW

The OpenSSL B<ssl> library implements the Secure Sockets Layer (SSL v2/v3) and

Transport Layer Security (TLS v1) protocols. It provides a rich API which is

documented here.

=head1 HEADER FILES

Currently the OpenSSL B<ssl> library provides the following C header files

containing the prototypes for the data structures and and functions:

At first the library must be initialized; see

L<SSL_library_init(3)|SSL_library_init(3)>.

=over 4

Then an B<SSL_CTX> object is created as a framework to establish

TLS/SSL enabled connections (see L<SSL_CTX_new(3)|SSL_CTX_new(3)>).

Various options regarding certificates, algorithms etc. can be set

in this object.

=item B<ssl.h>

When a network connection has been created, it can be assigned to an

B<SSL> object. After the B<SSL> object has been created using

L<SSL_new(3)|SSL_new(3)>, L<SSL_set_fd(3)|SSL_set_fd(3)> or

L<SSL_set_bio(3)|SSL_set_bio(3)> can be used to associate the network

connection with the object.

That's the common header file for the SSL/TLS API.  Include it into your

program to make the API of the B<ssl> library available. It internally

includes both more private SSL headers and headers from the B<crypto> library.

Whenever you need hard-core details on the internals of the SSL API, look

inside this header file.

=item B<ssl2.h>

That's the sub header file dealing with the SSLv2 protocol only.

I<Usually you don't have to include it explicitly because

it's already included by ssl.h>.

=item B<ssl3.h>

That's the sub header file dealing with the SSLv3 protocol only.

I<Usually you don't have to include it explicitly because

it's already included by ssl.h>.

=item B<ssl23.h>

That's the sub header file dealing with the combined use of the SSLv2 and

SSLv3 protocols.

I<Usually you don't have to include it explicitly because

it's already included by ssl.h>.

=item B<tls1.h>

That's the sub header file dealing with the TLSv1 protocol only.

I<Usually you don't have to include it explicitly because

it's already included by ssl.h>.

=back

Then the TLS/SSL handshake is performed using

L<SSL_accept(3)|SSL_accept(3)> or L<SSL_connect(3)|SSL_connect(3)>

respectively.

L<SSL_read(3)|SSL_read(3)> and L<SSL_write(3)|SSL_write(3)> are used

to read and write data on the TLS/SSL connection.

L<SSL_shutdown(3)|SSL_shutdown(3)> can be used to shut down the

TLS/SSL connection.

=head1 DATA STRUCTURES

=back

=head1 HEADER FILES

Currently the OpenSSL B<ssl> library provides the following C header files

containing the prototypes for the data structures and and functions:

=over 4

=item B<ssl.h>

That's the common header file for the SSL/TLS API.  Include it into your

program to make the API of the B<ssl> library available. It internally

includes both more private SSL headers and headers from the B<crypto> library.

Whenever you need hard-core details on the internals of the SSL API, look

inside this header file.

=item B<ssl2.h>

That's the sub header file dealing with the SSLv2 protocol only.

I<Usually you don't have to include it explicitly because

it's already included by ssl.h>.

=item B<ssl3.h>

That's the sub header file dealing with the SSLv3 protocol only.

I<Usually you don't have to include it explicitly because

it's already included by ssl.h>.

=item B<ssl23.h>

That's the sub header file dealing with the combined use of the SSLv2 and

SSLv3 protocols.

I<Usually you don't have to include it explicitly because

it's already included by ssl.h>.

=item B<tls1.h>

That's the sub header file dealing with the TLSv1 protocol only.

I<Usually you don't have to include it explicitly because

it's already included by ssl.h>.

=back

=head1 API FUNCTIONS

Currently the OpenSSL B<ssl> library exports 214 API functions.