How can I determine the Client Address from the ssl_socket which is defined as

typedef boost::asio::ssl::stream<boost::asio::ip::tcp::socket> ssl_socket;

ssl_socket::lowest_layer() gives you reference to the underlaying tcp socket (actually, to basic_stream_socket). From there, you can use any socket methods:

http://www.boost.org/doc/libs/1_37_0/doc/html/boost_asio/reference/basic_stream_socket.html

Eg., sslSocket.lowest_layer().remote_endpoint();// etc