/usr/include/asio/ssl/ is in libasio-dev 1.4.1-3ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/asio/ssl/basic_context.hpp
/usr/include/asio/ssl/context.hpp
/usr/include/asio/ssl/context_base.hpp
/usr/include/asio/ssl/context_service.hpp
/usr/include/asio/ssl/detail/
/usr/include/asio/ssl/detail/openssl_context_service.hpp
/usr/include/asio/ssl/detail/openssl_init.hpp
/usr/include/asio/ssl/detail/openssl_operation.hpp
/usr/include/asio/ssl/detail/openssl_stream_service.hpp
/usr/include/asio/ssl/detail/openssl_types.hpp
/usr/include/asio/ssl/stream.hpp
/usr/include/asio/ssl/stream_base.hpp
/usr/include/asio/ssl/stream_service.hpp