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.. index::
single: Systems; Emailout
========
Emailout
========
Purpose
=======
This system is used as outgoing mail relay for other infrastructure services.
Administration
==============
System Administration
---------------------
* Primary: :ref:`people_jandd`
* Secondary: :ref:`people_jselzer`
Contact
-------
* emailout-admin@cacert.org
Additional People
-----------------
:ref:`people_mario` has :program:`sudo` access on that machine too.
Basics
======
Physical Location
-----------------
This system is located in an :term:`LXC` container on physical machine
:doc:`infra02`.
Logical Location
----------------
:IP Internet: :ip:v4:`213.154.225.239`
:IP Intranet: :ip:v4:`172.16.2.10` (outbound SNAT) and :ip:v4:`172.16.2.32`
:IP Internal: :ip:v4:`10.0.0.32`
:MAC address: :mac:`00:ff:12:01:65:02` (eth0)
.. seealso::
See :doc:`../network`
DNS
---
.. index::
single: DNS records; Emailout
========================== ======== ====================================================================
Name Type Content
========================== ======== ====================================================================
emailout.cacert.org. IN A 213.154.225.239
emailout.cacert.org. IN SSHFP 1 1 1ba1ab632911e8a68a69521130120695086d858c
emailout.cacert.org. IN SSHFP 1 2 6e50d5b2034006b69eb7ba19d3f3fd2c48015bea2bb3d5e2a0f8cf25ff030055
emailout.cacert.org. IN SSHFP 2 1 0e8888352604dbd1cc4d201bc1e985d80b9cf752
emailout.cacert.org. IN SSHFP 2 2 a7402f014b47b805663c904dabbc9590db7d8d0f350cea6d9f63e12bc27bac0c
emailout.cacert.org. IN SSHFP 3 1 527004f2091d2cef2c28b5f8241fc0e76307b2ba
emailout.cacert.org. IN SSHFP 3 2 9094dcf8860523a83542ec4cc46fbcfed396f5525bc202cfecf42d1a7044136d
emailout.intra.cacert.org. IN A 172.16.2.32
========================== ======== ====================================================================
.. seealso::
See :wiki:`SystemAdministration/Procedures/DNSChanges`
Operating System
----------------
.. index::
single: Debian GNU/Linux; Stretch
single: Debian GNU/Linux; 9.4
* Debian GNU/Linux 9.4
Applicable Documentation
------------------------
The following packages where installed after the container setup::
apt-get install vim-nox screen aptitude git etckeeper postfix \
postfix-pcre opendkim opendkim-tools man-db rsyslog logrotate \
heirloom-mailx netcat-openbsd swaks
Services
========
Listening services
------------------
+----------+-----------+-----------+-----------------------------------------+
| Port | Service | Origin | Purpose |
+==========+===========+===========+=========================================+
| 22/tcp | ssh | ANY | admin console access |
+----------+-----------+-----------+-----------------------------------------+
| 25/tcp | smtp | intranet | mail delivery from intranet MTAs |
+----------+-----------+-----------+-----------------------------------------+
| 5666/tcp | nrpe | monitor | remote monitoring service |
+----------+-----------+-----------+-----------------------------------------+
Running services
----------------
.. index::
single: OpenDKIM
single: Postfix
single: cron
single: nrpe
single: openssh
single: rsyslog
+--------------------+--------------------+----------------------------------------+
| Service | Usage | Start mechanism |
+====================+====================+========================================+
| openssh server | ssh daemon for | init script :file:`/etc/init.d/ssh` |
| | remote | |
| | administration | |
+--------------------+--------------------+----------------------------------------+
| cron | job scheduler | init script :file:`/etc/init.d/cron` |
+--------------------+--------------------+----------------------------------------+
| rsyslog | syslog daemon | init script |
| | | :file:`/etc/init.d/syslog` |
+--------------------+--------------------+----------------------------------------+
| OpenDKIM | DKIM signing | init script |
| | daemon | :file:`/etc/init.d/opendkim` |
+--------------------+--------------------+----------------------------------------+
| Postfix | SMTP server for | init script |
| | local mail | :file:`/etc/init.d/postfix` |
| | submission, and | |
| | mail relay for | |
| | infrastructure | |
| | systems | |
+--------------------+--------------------+----------------------------------------+
| Nagios NRPE server | remote monitoring | init script |
| | service queried by | :file:`/etc/init.d/nagios-nrpe-server` |
| | :doc:`monitor` | |
+--------------------+--------------------+----------------------------------------+
Connected Systems
-----------------
* :doc:`monitor`
* SMTP (25/tcp) from other infrastructure systems
Outbound network connections
----------------------------
* DNS (53) resolving nameservers 172.16.2.2 and 172.16.2.3
* :doc:`emailout` as SMTP relay
* :doc:`proxyout` as HTTP proxy for APT
* SMTP (25/tcp) to :doc:`email`, :doc:`issue` and :doc:`lists`
Security
========
.. sshkeys::
:RSA: SHA256:blDVsgNABraet7oZ0/P9LEgBW+ors9XioPjPJf8DAFU MD5:56:09:89:92:af:3c:15:e4:a3:06:11:63:0e:be:b6:a2
:DSA: SHA256:p0AvAUtHuAVmPJBNq7yVkNt9jQ81DOptn2PhK8J7rAw MD5:6c:8d:31:c4:92:de:f0:a8:95:eb:fe:20:83:91:ca:07
:ECDSA: SHA256:kJTc+IYFI6g1QuxMxG+8/tOW9VJbwgLP7PQtGnBEE20 MD5:cb:3c:69:c5:a1:90:c6:8e:55:40:83:6c:10:3f:09:b4
:ED25519: SHA256:TOtIitF+p8jbFh/fM1fic9LqH+W+GDeUqs18S/36qKU MD5:04:ca:72:d0:21:0a:4a:8b:a5:f7:a2:2f:10:e5:3f:92
Non-distribution packages and modifications
-------------------------------------------
* None
Risk assessments on critical packages
-------------------------------------
Postfix has a very good security reputation. The system is patched regularly.
Critical Configuration items
============================
Keys and X.509 certificates
---------------------------
.. todo:: setup a proper certificate for incoming STARTTLS
.. index::
pair: DKIM; Private Key
see: DKIM; OpenDKIM
* :file:`/etc/dkim/2015.private` contains the RSA private key to be used for
:term:`DKIM` signing by OpenDKIM.
.. index::
pair: DKIM; DNS
see: DNS; OpenDKIM
* :file:`/etc/dkim/2015.txt` contains a textual DNS record representation for
the public component of the DKIM signing key
.. seealso::
* :wiki:`SystemAdministration/CertificateList`
.. index::
pair: Postfix; configuration
Postfix configuration
---------------------
Postfix has been configured as outgoing email relay with very little changes to
the default configuration.
The mailname has been set to ``cacert.org`` in :file:`/etc/mailname`.
Postfix configuration file:`/etc/postfix/main.cf` and :file:`/etc/postfix/dynamic_maps.cf` have been modified to:
* set infrastructure related host and network parameters
* allow regular expressions in maps
* activate opportunistic TLS
* prepare for DKIM support
* disable local delivery
.. literalinclude:: ../configdiff/emailout/postfix-main.cf
:language: text
Emails sent to specific intranet hostnames are rewritten to their respective
admin addresses in :file:`/etc/postfix/canonical_maps`:
.. literalinclude:: ../configdiff/emailout/canonical_maps
:language: text
Emails sent to specific cacert.org hostnames are forwarded via
:file:`/etc/postfix/transport`:
.. literalinclude:: ../configdiff/emailout/transport
:language: text
:file:`/etc/postfix/transport` has to be rehashed if it is changed because
Postfix uses a binary representation in :file:`/etc/postfix/transport.db`. To
perform the rehashing and restart Postfix use::
postmap hash:/etc/postfix/transport
service postfix restart
.. index::
pair: OpenDKIM; configuration
OpenDKIM configuration
----------------------
.. todo::
enable OpenDKIM in Postfix configuration when the DNS record is in place and
:doc:`email` is ready for DKIM too or is configured to send mail via
emailout.
The OpenDKIM configuration is stored in :file:`/etc/opendkim.conf`. The
following lines have been added:
.. code:: diff
--- opendkim.conf.dpkg-dist 2017-09-04 00:17:50.000000000 +0000
+++ opendkim.conf 2018-02-16 13:38:55.545110292 +0000
@@ -13,6 +13,11 @@
#Domain example.com
#KeyFile /etc/dkimkeys/dkim.key
#Selector 2007
+Domain cacert.org
+KeyFile /etc/dkim/2015.private
+Selector 2015
+
+InternalHosts /etc/dkim/internalhosts
# Commonly-used options; the commented-out versions show the defaults.
#Canonicalization simple
@@ -31,7 +36,7 @@
# ## local:/path/to/socket to listen on a UNIX domain socket
#
#Socket inet:8892@localhost
-Socket local:/var/run/opendkim/opendkim.sock
+Socket local:/var/spool/postfix/opendkim/opendkim.sock
## PidFile filename
### default (none)
The key has been generated with::
mkdir /etc/dkim
cd /etc/dkim
opendkim-genkey -d cacert.org -s 2015
Internal networks have been defined in :file:`/etc/dkim/internalhosts` as::
127.0.0.1
10.0.0.0/24
172.16.2.0/24
Tasks
=====
Planned
-------
.. todo:: setup IPv6
Changes
=======
System Future
-------------
* No plans
Additional documentation
========================
.. seealso::
* :wiki:`PostfixConfiguration`
References
----------
Postfix documentation
http://www.postfix.org/documentation.html
Postfix Debian wiki page
https://wiki.debian.org/Postfix
OpenDKIM documentation
http://www.opendkim.org/docs.html
|
