README: rewrite installation instructions

README.rst

@@ -151,29 +151,56 @@ Also, Martin Giess has created an auto-deployment process with vagrant/ansible,
 tested with VirtualBox/AWS/DigitalOcean - see https://github.com/EMnify/matrix-synapse-auto-deploy
 for details.
 
-To set up your homeserver, run (in your virtualenv, as before)::
+Configuring synapse
+-------------------
+
+Before you can start Synapse, you will need to generate a configuration
+file. To do this, run (in your virtualenv, as before)::
 
     cd ~/.synapse
     python -m synapse.app.homeserver \
-        --server-name machine.my.domain.name \
+        --server-name my.domain.name \
         --config-path homeserver.yaml \
         --generate-config \
         --report-stats=[yes|no]
 
-...substituting your host and domain name as appropriate.
+... substituting an appropriate value for ``--server-name``. The server name
+determines the "domain" part of user-ids for users on your server: these will
+all be of the format ``@user:my.domain.name``. It also determines how other
+matrix servers will reach yours for `Federation`_. For a test configuration,
+set this to the hostname of your server. For a more production-ready setup, you
+will probably want to specify your domain (``example.com``) rather than a
+matrix-specific hostname here (in the same way that your email address is
+probably ``user@example.com`` rather than ``user@email.example.com``) - but
+doing so may require more advanced setup - see `Setting up Federation`_.
 
-This will generate you a config file that you can then customise, but it will
+This command will generate you a config file that you can then customise, but it will
 also generate a set of keys for you. These keys will allow your Home Server to
 identify itself to other Home Servers, so don't lose or delete them. It would be
 wise to back them up somewhere safe. If, for whatever reason, you do need to
 change your Home Server's keys, you may find that other Home Servers have the
 old key cached. If you update the signing key, you should change the name of the
-key in the <server name>.signing.key file (the second word) to something different.
+key in the ``<server name>.signing.key`` file (the second word) to something different.
 
-By default, registration of new users is disabled. You can either enable
-registration in the config by specifying ``enable_registration: true`` (it is
-then recommended to also set up CAPTCHA - see `<docs/CAPTCHA_SETUP.rst>`_), or
-you can use the command line to register new users::
+The default configuration exposes two TCP ports: 8008 and 8448. Port 8008 is
+configured without TLS; it is not recommended this be exposed outside your
+local network. Port 8448 is configured to use TLS with a self-signed
+certificate. This is fine for testing with but you will almost certainly want
+to use another certificate for production purposes. You can do so by changing
+``tls_certificate_path``, ``tls_private_key_path`` and ``tls_dh_params_path``
+in ``homeserver.yaml``; alternatively, you can use a reverse-proxy, but be sure
+to read `Using a reverse proxy with Synapse`_ when doing so.
+
+Registering a user
+------------------
+
+You will need at least one user on your server in order to use a Matrix
+client. Users can be registered either `via a Matrix client`__, or via a
+commandline script.
+
+.. __: `client-user-reg`_
+
+To get started, is easiest to use the command line to register new users::
 
     $ source ~/.synapse/bin/activate
     $ synctl start # if not already running
@@ -183,6 +210,16 @@ you can use the command line to register new users::
     Confirm password:
     Success!
 
+This process uses a setting ``registration_shared_secret`` in
+``homeserver.yaml``, which is shared between Synapse itself and the
+``register_new_matrix_user`` script. It doesn't matter what it is (a random
+value is generated by ``--generate-config``), but it should be kept secret, as
+anyone with knowledge of it can register users on your server even if
+``enable_registration`` is ``false``.
+
+Setting up a TURN server
+------------------------
+
 For reliable VoIP calls to be routed via this homeserver, you MUST configure
 a TURN server.  See `<docs/turn-howto.rst>`_ for details.
 
@@ -215,9 +252,18 @@ start sending messages.
 as of the time of writing it is somewhat outdated and not really recommended -
 https://github.com/matrix-org/synapse/issues/1527).
 
+.. _`client-user-reg`:
+
 Registering a new user from a client
 ------------------------------------
 
+By default, registration of new users via Matrix clients is disabled. To enable
+it, specify ``enable_registration: true`` in ``homeserver.yaml``. (It is then
+recommended to also set up CAPTCHA - see `<docs/CAPTCHA_SETUP.rst>`_.)
+
+Once ``enable_registration`` is set to ``true``, it is possible to register a
+user via `riot.im <https://riot.im/app/#/register>`_ or other Matrix clients.
+
 Your new user name will be formed partly from the ``server_name`` (see
 `Configuring synapse`_), and partly from a localpart you specify when you
 create the account. Your name will take the form of::
@@ -432,6 +478,7 @@ versions of synapse.
 
 .. _UPGRADE.rst: UPGRADE.rst
 
+.. _federation:
 
 Setting up Federation
 =====================