Installation
============

Hippotat is written in Rust.
The documentation is procssed with Sphinx.

It is most convenient to install (especailly the server) as a `.deb`.

Building
--------

On a system with a new enough `cargo` and `rustc`:

```
   apt-get build-dep .
   CARGO='cargo --locked' dpkg-buildpackage -uc -b
```

Sadly, Debian bullseye is not new enough;
to build there you will need to install Rust from upstream e.g.
[using Rustup](https://www.rust-lang.org/learn/get-started).

In any case, the build runes above will download dependencies
from the upstream Rust package repository.
The precise versions of those dependencies, and their precise contents,
are controlled and checked
by the `Cargo.lock` file shipped in the Hippotat source tree,
provided that `cargo --locked` is used.

If you don't want to install debs,
you can also just use cargo to build the two binaries,
`hippotat` and `hippotatd`.
You could perhaps even `cargo install hippotat` on a client machine.


Installation
------------

 * On the server: `apt install hippotat-{server,common}_*.deb`
 * On the client: `apt install hippotat-{client,common}_*.deb`

This will also install the `userv` privsep tool,
and the `userv-ipif` utility for unprivileged network interface management.


Configuration
-------------

You will need to:

 1. Choose a suitable URL that Hippotat will be able to listen on.
    This should be port 80, or 443 with TLS.
    You can use a reverse proxy
    (but you may want to suppress some of the logging).
    If using a reverse proxy,
    you must choose an internal IP port for the Hippotat server to use.

 2. Select a private network range for use by the IP-over-HTTP system,
    and assign addresses to the server and to each client.
    If you use a range from RFC1918, choose it at random,
    eg using the [Cambridge G-RIN](https://www.ucam.org/cam-grin/).

 3. Configure your firewalls to restrict access from that range
    to internal resources
    (eg, which might otherwise trust Hippotat addresses due to them
    being in RFC1918 private use ranges).
    Note that
    **Hippotat does not provide strong authentication or confidentiality**.

 4. Configure `authbind` to allow the service user `_hippotat`
    (created by the package installation)
    to bind to the port you have chosen,
    on the server.

 5. Configure `ipif` to allow
    the service user `_hippotat` (on the server)
    or your own user (on the client)
    to create network interfaces
    using addresses in the range you have assigned.

 6. Configure `hippotat` itself, at both ends.


Startup - server
----------------

The `hippotat-server` package
supplies an init script
which will start the `hippotatd` server program,
if `/etc/hippotat/main.cfg` exists.
If you just created that file, 
`service hippotatd start` will start the server..

Consult the init script to see options you can put in
`/etc/default/hippotat`.


Usage - client
--------------

It is not usual to have hippotat running all the time,
since its approach is rather wasteful,
and not needed in a sensible network environment.

When you find yourself in a bad network environment,
run `hippotat` from a shell.
It will bring up the hippotat link.
When you don't need Hippotat any more, simply `^C` it.

With the link up you can `ssh` (or, maybe, `mosh`) to the server,
using the server's Hippotat IP address.
If you are using [secnet](https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git/secnet.git/)'s polypath feature,
secnet will automatically start to use hippotat.

Don't send traffic you care about unencrypted over Hippotat.
Hippotat's security mechanisms are designed
to try to minimise denial of service,
especially by off-path entities,
but **data confidentiality and integrity are not provided**.


Troubleshooting
---------------

The server will log to syslog, facility `daemon`, by default.

The client will report its progress to stderr.