mirror of
https://kernel.googlesource.com/pub/scm/linux/kernel/git/tglx/remail.git
synced 2024-11-22 04:12:38 +01:00
95 lines
3.8 KiB
ReStructuredText
95 lines
3.8 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
.. _remail_introduction:
|
|
|
|
Introduction
|
|
============
|
|
|
|
remail is a very simplistic mailing list tool which provides encryption.
|
|
|
|
Why yet another mailing list tool?
|
|
----------------------------------
|
|
|
|
The handling of the embargoed hardware security issues made it necessary
|
|
to have a encrypted mailing list. Managing Cc lists manually and dealing
|
|
with the odd GPG integrations in the mail clients is just not a workable
|
|
solution.
|
|
|
|
There are only a few Open Source implementations of encrypted mailing lists
|
|
available. Some of them are abandoned projects. The alive ones have their
|
|
own set of shortcomings. One of them supports only S/MIME. The other
|
|
supports only PGP, but did not survive testing in a real world
|
|
deployment. Repairing ruby code and dis-tangling the thing from its weird
|
|
daemons and other over-engineered features was certainly not a project for
|
|
the weekend.
|
|
|
|
After thinking about it for a while, I recognized that for the purpose at
|
|
hand the tool can be very simplistic. Using existing tools like getmail and
|
|
SMTP servers plus the knowledge about the gory details of emails which I
|
|
gained by writing mail handling scripts in python for my daily work, made
|
|
it possible to implement it in a rather short time.
|
|
|
|
|
|
What it does
|
|
------------
|
|
|
|
remail reads mail from a maildir, decrypts it with the mailing list private
|
|
key and re-encrypts it for every enabled subscriber. The resulting mails are
|
|
delivered to the localhost's SMTP server.
|
|
|
|
remail supports S/MIME and PGP on both ends.
|
|
|
|
No MUA functionality and no complicated SMTP delivery mechanisms are
|
|
required. They all exist in well maintained tools already.
|
|
|
|
The list configuration is a simple yaml file and is maintained manually
|
|
with your favorite text editor. Building tools around that is not part of
|
|
this project and there are many existing ways to handle that conveniently.
|
|
|
|
The proven in use mechanism is to have the configuration files in git and
|
|
let the mailing list system either check for updates regularly or get some
|
|
external notification that a new configuration is available.
|
|
|
|
|
|
What it does not
|
|
----------------
|
|
|
|
It does not care about mail transport on the receiving side, no POP or IMAP
|
|
support as this can be handled by tools like getmail.
|
|
|
|
It does not care about complex mail transport on the sending side as this
|
|
can be handled by SMTP servers like postfix or exim.
|
|
|
|
It has no integration into SMTP server transports or filters because it
|
|
makes no sense to deploy such a sensitive mechanism on a public facing
|
|
machine.
|
|
|
|
It does not come with GUI and managenent tools. A crypto mailing list is
|
|
subscribers only for obvious reasons and not meant to handle a large amount
|
|
of subscribers. It's meant for secure communications of a small group of
|
|
people without having the hassle of keeping Cc lists up to date and
|
|
encrypting for every recipient.
|
|
|
|
|
|
How it works
|
|
------------
|
|
|
|
.. image:: remail.svg
|
|
|
|
The mailing list has the usual post, bounce and owner email addresses on a
|
|
public mail server. These addresses are aliased to a user account. The
|
|
mails are stored in the users inbox or forwarded to a protected machine.
|
|
|
|
The mailing list software runs on a protected and separated machine behind
|
|
firewalls and access barriers like any other sensitive application.
|
|
|
|
The mail is retrieved from the public facing machine by any of the existing
|
|
mechanisms, e.g. getmail, fetchmail or any MTA which can deliver mail to a
|
|
maildir. remail does not implement any transport on the incoming side as
|
|
there are good tools available which can handle the requirements of a
|
|
particular setup.
|
|
|
|
The list daemon retrieves the mails from the maildir and selects the
|
|
appropriate list via the 'To' header. It then decrypts the incoming mail,
|
|
re-encrypts it for each subscriber and delivers it to the local SMTP server
|
|
which takes care of relaying it to the public facing SMTP server.
|