path: root/fripost-docs.org

# -*- mode: org-mode; truncate-lines: nil -*-
#+TITLE: Systems documentation
#+AUTHOR: Fripost -- the Free E-mail Association
#+DESCRIPTION: Systems documentation for Fripost, the Free E-mail Association
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#+DRAWERS: HIDDEN STATE PROPERTIES CONTENT
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Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
Version 1.3 or any later version published by the Free Software
Foundation; with no Invariant Sections, no Front-Cover Texts and
no Back-Cover Texts.  A copy of the license is included in a
separate file called "COPYING".

This is the documentation of the server configuration used by the free e-mail
association, given here to provide a transparent system.

Debian GNU/Linux squeeze is the current target system. We might keep some notes
for lenny for some time yet since there might still be servers that have not
been upgraded.

The complete documentation is the actual configuration files on the servers.
This document intends to give a general idea of the setup and be of help if we
need to recreate a crashed server.  Also, if an administrator goes AWOL, it
should be easy to pick up where he left of.

The steps taken here will not necessarily give a perfect replica of our systems.
We are constantly (yes, constantly) working on improving the security and
reliability of our systems.  We do not think of security as a shoot and forget
sort of thing but instead as an ongoing effort.  Thus, while we strive to
document all configuration that we consider stable enough, the documentation may
sometimes lag behind.

We do not believe in security through obscurity. This means we are aiming
instead for a system that fulfills [[http://en.wikipedia.org/wiki/Kerckhoffs%27s_Principle][Kerckhoffs's Principle]]. However, some
information below might have been changed to inconvenience a potential
attacker. Beware and take according measures.

We welcome all criticism, suggestions for improvements, additions etc.  Please
send them to skangas@skangas.se.

* Basic Setup -- Checklist after having installed a new Debian GNU/Linux-server
** Basic installation instructions

- Use expert install to maximize fun.
- Preferably, only install the "Standard system utilities" and "SSH Server" tasks.
- Make sure to answer "yes" to shadow passwords and MD5.
- Do disable the root account.

** Install etckeeper

Install etckeeper immediately after install, to start tracking /etc.

** Uninstall a bunch of unnecessary packages

sudo aptitude remove --purge debian-faq dictionaries-common doc-debian \
doc-linux-text iamerican ibritish iswedish ispell laptop-detect nfs-common \
openbsd-inetd portmap tasksel tasksel-data w3m wbritish

** Packages to install
*** Administrative

sudo aptitude install emacs23-nox harden-servers logcheck molly-guard ntp \
ntpdate openssh-server rsync screen syslog-summary sudo unattended-upgrades

# If the system is on a dynamic IP (e.g. using DHCP):
sudo aptitude install resolvconf

# NB: harden-clients conflicts with telnet, which as we know is very handy
# during configuration.  Therefore, only optionally:
sudo aptitude install harden-clients

** Use GNU Emacs as the default editor

# NOTE: Emacs will be the default on all Fripost systems. If you prefer
# something else, use the EDITOR environment variable.

sudo update-alternatives --config editor
 
** Configure sudo

# If you disabled root account during installation, the default account is
# already in the sudo group.  Otherwise, follow these steps:

sudo adduser myuser sudo

sudo EDITOR="emacs" visudo

     %sudo ALL= (ALL) ALL

** Configure sshd

Make sure your private key is in ~/.ssh/authorized_keys2

:: /etc/ssh/sshd_config

    # Add relevant users here
    AllowUsers xx yy zz
    
    # Change these settings
    PermitRootLogin no
    PasswordAuthentication no
    X11Forwarding no
    
sudo /etc/init.d/ssh restart
   
# Without closing the current connection, try to connect to the server,
# verifying that you can still connect.

** Forward root email 

:: /etc/aliases

    root: admin@fripost.org

** Configure logcheck

sudo aptitude install logcheck syslog-summary

:: /etc/logcheck/logcheck.conf

     INTRO=0
     SENDMAILTO="admin@fripost.org"

:: /etc/logcheck/ignore.d.server/local

# XXX: not always necessary?
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ rsyslogd: \[origin software="rsyslogd" swVersion="[0-9.]+" x-pid="[0-9]+" x-info="http://www.rsyslog.com"\] rsyslogd was HUPed, type '(restart|lightweight)'\.$
# XXX: necessary with squeeze?
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ ntpd\[[0-9]+\]: kernel time sync (disabled|enabled) [0-9]+$
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ ntpd\[[0-9]+\]: kernel time sync (disabled|enabled|status( change)?) [0-9]+$
# not necessary with squeeze
^\w{3} [ :[:digit:]]{11} [._[:alnum:]-]+ sshd\[[[:digit:]]+\]: Received disconnect from [:[:xdigit:].]+: [[:digit:]]+: disconnected by user$
# not necessary with squeeze
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ kernel:( \[[[:digit:]]+\.[[:digit:]]+\])? imklog [0-9.]+, log source = /proc/kmsg started.$
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ rsyslogd: \[origin software="rsyslogd" swVersion="[0-9.]+" x-pid="[0-9]+" x-info="http://www.rsyslog.com"\] restart$
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ kernel: Kernel logging \(proc\) stopped.$
# ddclient
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ ddclient\[[0-9]+\]: FAILED:   updating [,._[:alnum:]-]+: Could not connect to dns.loopia.se/xdyndnsserver/xdyndns.php.$
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ ddclient\[[0-9]+\]: WARNING:  TIMEOUT: dns.loopia.se after 120 seconds$
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ ddclient\[[0-9]+\]: WARNING:  cannot connect to dns.loopia.se:80 socket: IO::Socket::INET: Bad hostname 'dns.loopia.se'$
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ ddclient\[[0-9]+\]: WARNING:  cannot connect to dns.loopia.se:80 socket: IO::Socket::INET: connect: Connection timed out$
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ ddclient\[[0-9]+\]: WARNING:  cannot connect to dns.loopia.se:443 socket: IO::Socket::SSL: SSL connect attempt failed because of handshake problemserror:00000000:lib(0):func(0):reason(0) IO::Socket::INET configuration failederror:00000000:lib(0):func(0):reason(0)$
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ ddclient\[[0-9]+\]: WARNING:  cannot connect to dns.loopia.se:443 socket: IO::Socket::SSL: SSL connect attempt failed with unknown errorerror:00000000:lib(0):func(0):reason(0) IO::Socket::INET configuration failederror:00000000:lib(0):func(0):reason(0)$
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ ddclient\[[0-9]+\]: WARNING:  cannot connect to dns.loopia.se:443 socket: IO::Socket::SSL: Timeout IO::Socket::INET configuration failederror:00000000:lib(0):func(0):reason(0)$
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ ddclient\[[0-9]+\]: WARNING:  file /var/cache/ddclient/ddclient.cache, line [0-9]+: Invalid Value for keyword 'ip' = ''$
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ ddclient\[[0-9]+\]: WARNING:  updating [._[:alnum:]-]+: nochg: No update required; unnecessary attempts to change to the current address are considered abusive$
^\w{3} [ :0-9]{11} [._[:alnum:]-]+ ntpd\[[0-9]+\]: [.0-9]{7,15} interface [.0-9]{7,15} -> [.0-9]{7,15}$

** Configuring aptitude and friends

# We are going to automatically install many security updates using the package
# "unattended-upgrades".  Automated upgrades are in general not a very good
# idea, but "unattended-upgrades" takes steps to mitigate the problems with this
# approach.  Given the Debian security teams track record in recent years we
# believe the positives outweigh the negatives.
#
# For the situations when unattended-upgrades fails (e.g. when there are
# configuration changes), there is an e-mail sent to the administrator.
#

:: /etc/apt/apt.conf

    APT
    {
      // Configuration for /etc/cron.daily/apt
      Periodic
      {
         // Do "apt-get update" automatically every n-days (0=disable)
         Update-Package-Lists "1";
         // Do "apt-get autoclean" every n-days (0=disable)
         AutocleanInterval "1";
         // Do "apt-get upgrade --download-only" every n-days (0=disable)
         Download-Upgradeable-Packages "1";
         // Run the "unattended-upgrade" security upgrade script every n days
         Unattended-Upgrade "1";
      }
    };
    
    Aptitude
    {
      UI
      {
         Autoclean-After-Update:         true;
         Auto-Fix-Broken:                false;
         Keep-Recommends:                true;
         Recommends-Important:           true;
         Description-Visible-By-Default: false;
         HelpBar                         false;
         Menubar-Autohide                true;
         Purge-Unused:                   true;
         Prompt-On-Exit                  false;
      }
    }

# Using Debian squeeze:
:: /etc/apt/apt.conf.d/50unattended-upgrades

     Unattended-Upgrade::Mail "admin@fripost.org";

** Configure ddclient

:: /etc/ddclient.conf

### Not reproduced here due to containing sensitive information

:: /etc/default/ddclient

    run_daemon="true"


* Next Steps
** Configuring the backup solution

*** Bacula configuration

*** Simple rsync solution

General idea [[http://wikis.sun.com/display/BigAdmin/Using+rdist+rsync+with+sudo+for+remote+updating][from here]].  This is just a basic setup for now, will need to be
changed to rsnapshot or perhaps something even more sophisticated like bacula.

1. Install rsync
      - sudo aptitude install rsync
2. Create a key on the backup computer:
      - sudo mkdir /root/.ssh/backup_key
      - sudo ssh-keygen -N "" -b 4096 -f /root/.ssh/backup_key
      - cat /root/.ssh/backup_key.pub
3. Create a user on the computer that will be backed up
      - sudo adduser --disabled-password remupd
      - add the public key from above to ~remupd/.ssh/authorized_keys2
        prefix with: no-X11-forwarding,no-agent-forwarding,no-port-forwarding
      - sudo EDITOR="emacs" visudo
        Cmnd_Alias      RSYNCDIST=/usr/bin/rsync
        remupd	ALL=NOPASSWD:RSYNCDIST
4. Test the key from the backup computer:
      - ssh -i ~/.ssh/backup_key -l remupd example.com
5. Create a script on the backup computer to automatically backup
6. Add script to crontab

** Configuring the e-mail servers
*** Introduction
**** Overview

We will be using one main mail storage server, accessible by users via IMAP.
This server should be referred to as the main `IMAP server'. We will have two or
more mail gateways that will relay e-mail to the main server over secure
connections.  These are called `smarthosts'.

The main server will also be responsible for keeping all users in an MySQL
database that will be replicated using MySQL.

**** Definitions

IMAP server = the main storage server

smarthost = the server receiving email from the internet (configured as MX)

*** Configuring an SSH tunnel between two hosts

# Definitions:
# originating host = the host that will be connecting
# destination host = the host that runs some service

# Begin by setting a few environment variables:

TUNNEL_KEY_FILE="my_tunnel_key"
TUNNEL_USER="tunneluser"
TUNNEL_HOME="/home/$TUNNEL_USER"
DEST_PORT="25"
ORIGIN_PORT="1917"

**** Prepare origin

1. Create a key on the originating host:

   sudo ssh-keygen -N "" -b 4096 -f /root/.ssh/$TUNNEL_KEY_FILE
   sudo cat /root/.ssh/$TUNNEL_KEY_FILE.pub

**** Prepare destination

2a. Install necessary software on the destination host:

   sudo aptitude install netcat-openbsd

2b. Create a new user on the destination host:

   sudo adduser --home=$TUNNEL_HOME --shell=`type rbash|cut -d' ' -f3` \
                --disabled-password $TUNNEL_USER
   echo "exit" | sudo -u $TUNNEL_USER tee $TUNNEL_HOME/.bash_profile

   # Note: We need bash, so we can not change the shell to something else.

2c. Add $TUNNEL_USER to AllowUsers in /etc/ssh/sshd_config.

    sudo /etc/init.d/ssh restart

    # make sure the host is still reachable

2d. Add the public key from above to this user:

   THE_PUBLIC_KEY="ssh-rsa xxxxxxxxxxx" # from above

      sudo -u $TUNNEL_USER mkdir -p $TUNNEL_HOME/.ssh
      echo "command=\"nc localhost $DEST_PORT\",no-X11-forwarding,no-agent-forwarding,no-port-forwarding $THE_PUBLIC_KEY" | sudo -u $TUNNEL_USER tee -a $TUNNEL_HOME/.ssh/authorized_keys2

**** Set up the tunnel

3. Test the key on the originating host:

   sudo ssh -v -l $TUNNEL_USER -i /root/.ssh/$TUNNEL_KEY_FILE destination.example.com

    # Comment: You should be greeted by e.g.:
    # 220 mistral.fripost.org ESMTP Postfix (Debian/GNU)

4. Configure openbsd-inetd on the originating host:

   # Comment: We use inetd instead of ssh -L because, among other things, ssh
   #          -L tends to hang.

   sudo aptitude install openbsd-inetd

   :: /etc/inetd.conf
    
       127.0.0.1:$ORIGIN_PORT  stream  tcp     nowait  root    /usr/bin/ssh    -q -T -i /root/.ssh/$TUNNEL_KEY_FILE $TUNNEL_USER@example.com

    sudo service openbsd-inetd restart

You should now be able to connect through the tunnel from the originating
host using something like:

telnet localhost $ORIGIN_PORT

*** Installing MySQL
     - sudo apt-get install mysql-server
     - generate a long (25 characters) password for the mysql root user
     - /etc/mysql/my.cnf: skip-innodb
*** MySQL on the main IMAP server
**** Overview

We will use four tables `alias', `domain', `log' and `mailbox'.
  
***** mysql> show tables;
+----------------+
| Tables_in_mail |
+----------------+
| alias          | 
| domain         | 
| log            | 
| mailbox        | 
+----------------+
4 rows in set (0.00 sec)

***** mysql> describe alias;
+-------------+--------------+------+-----+---------------------+-------+
| Field       | Type         | Null | Key | Default             | Extra |
+-------------+--------------+------+-----+---------------------+-------+
| address     | varchar(255) | NO   | PRI |                     |       | 
| goto        | text         | NO   |     | NULL                |       | 
| domain      | varchar(255) | NO   |     |                     |       | 
| create_date | datetime     | NO   |     | 0000-00-00 00:00:00 |       | 
| change_date | timestamp    | NO   |     | CURRENT_TIMESTAMP   |       | 
| active      | tinyint(4)   | NO   |     | 1                   |       | 
+-------------+--------------+------+-----+---------------------+-------+
6 rows in set (0.00 sec)

***** mysql> describe domain;
+-------------+--------------+------+-----+---------------------+-------+
| Field       | Type         | Null | Key | Default             | Extra |
+-------------+--------------+------+-----+---------------------+-------+
| domain      | varchar(255) | NO   | PRI |                     |       | 
| description | varchar(255) | NO   |     |                     |       | 
| create_date | datetime     | NO   |     | 0000-00-00 00:00:00 |       | 
| change_date | timestamp    | NO   |     | CURRENT_TIMESTAMP   |       | 
| active      | tinyint(4)   | NO   |     | 1                   |       | 
+-------------+--------------+------+-----+---------------------+-------+
5 rows in set (0.00 sec)

***** mysql> describe log;
+-------+-------------+------+-----+-------------------+----------------+
| Field | Type        | Null | Key | Default           | Extra          |
+-------+-------------+------+-----+-------------------+----------------+
| id    | int(11)     | NO   | PRI | NULL              | auto_increment | 
| user  | varchar(20) | NO   |     |                   |                | 
| event | text        | NO   |     | NULL              |                | 
| date  | timestamp   | NO   |     | CURRENT_TIMESTAMP |                | 
+-------+-------------+------+-----+-------------------+----------------+
4 rows in set (0.00 sec)

***** mysql> describe mailbox;
+-------------+--------------+------+-----+---------------------+-------+
| Field       | Type         | Null | Key | Default             | Extra |
+-------------+--------------+------+-----+---------------------+-------+
| username    | varchar(255) | NO   | PRI |                     |       | 
| password    | varchar(255) | NO   |     |                     |       | 
| name        | varchar(255) | NO   |     |                     |       | 
| maildir     | varchar(255) | NO   |     |                     |       | 
| domain      | varchar(255) | NO   |     |                     |       | 
| create_date | datetime     | NO   |     | 0000-00-00 00:00:00 |       | 
| change_date | timestamp    | NO   |     | CURRENT_TIMESTAMP   |       | 
| active      | tinyint(4)   | NO   |     | 1                   |       | 
+-------------+--------------+------+-----+---------------------+-------+
8 rows in set (0.00 sec)

**** Steps to produce it
mysql -u root -p

   create database mail;

sudo mysql -u root -p --database=mail
FIXME: Not 100 % up to date
       :HIDDEN:
DROP TABLE IF EXISTS `alias`;
SET @saved_cs_client     = @@character_set_client;
SET character_set_client = utf8;
CREATE TABLE `alias` (
  `address` varchar(255) NOT NULL default '',
  `goto` text NOT NULL,
  `domain` varchar(255) NOT NULL default '',
  `create_date` datetime NOT NULL default '0000-00-00 00:00:00',
  `change_date` datetime NOT NULL default '0000-00-00 00:00:00',
  `active` tinyint(4) NOT NULL default '1',
  PRIMARY KEY  (`address`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COMMENT='Virtual Aliases - mysql_virtual_\nalias_maps';
SET character_set_client = @saved_cs_client;

DROP TABLE IF EXISTS `domain`;
SET @saved_cs_client     = @@character_set_client;
SET character_set_client = utf8;
CREATE TABLE `domain` (
  `domain` varchar(255) NOT NULL default '',
  `description` varchar(255) NOT NULL default '',
  `create_date` datetime NOT NULL default '0000-00-00 00:00:00',
  `change_date` datetime NOT NULL default '0000-00-00 00:00:00',
  `active` tinyint(4) NOT NULL default '1',
  PRIMARY KEY  (`domain`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COMMENT='Virtual Domains - mysql_virtual_\ndomains_maps';
SET character_set_client = @saved_cs_client;

DROP TABLE IF EXISTS `log`;
SET @saved_cs_client     = @@character_set_client;
SET character_set_client = utf8;
CREATE TABLE `log` (
  `id` int(11) NOT NULL auto_increment,
  `user` varchar(20) NOT NULL default '',
  `event` text NOT NULL,
  `date` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=106 DEFAULT CHARSET=utf8 COMMENT='log table';
SET character_set_client = @saved_cs_client;

DROP TABLE IF EXISTS `mailbox`;
SET @saved_cs_client     = @@character_set_client;
SET character_set_client = utf8;
CREATE TABLE `mailbox` (
  `username` varchar(255) NOT NULL default '',
  `password` varchar(255) NOT NULL default '',
  `name` varchar(255) NOT NULL default '',
  `maildir` varchar(255) NOT NULL default '',
  `domain` varchar(255) NOT NULL default '',
  `create_date` datetime NOT NULL default '0000-00-00 00:00:00',
  `change_date` timestamp NOT NULL default CURRENT_TIMESTAMP on update CURRENT_TIMESTAMP,
  `active` tinyint(4) NOT NULL default '1',
  PRIMARY KEY  (`username`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COMMENT='Virtual Mailboxes - mysql_virtua\nl_mailbox_maps';
SET character_set_client = @saved_cs_client;
        :END:

mysql -u root -p

# Create triggers

       use mail;

       DELIMITER $$
       CREATE TRIGGER alias_set_created_on_insert before insert on alias
         for each row begin set new.create_date = current_timestamp; end$$
       CREATE TRIGGER domain_set_created_on_insert before insert on domain
         for each row begin set new.create_date = current_timestamp; end$$
       CREATE TRIGGER mailbox_set_created_on_insert before insert on mailbox 
         for each row begin set new.create_date = current_timestamp; end$$
       DELIMITER ;
       
# Create mail user

       CREATE USER 'mail'@'localhost' IDENTIFIED BY '<password>';
       GRANT SELECT ON mail.alias   TO 'mail'@'localhost';
       GRANT SELECT ON mail.domain  TO 'mail'@'localhost';
       GRANT SELECT ON mail.mailbox TO 'mail'@'localhost';

*** Configuring the MySQL replication
***** Overview
[[http://dev.mysql.com/doc/refman/5.0/en/replication.html][MySQL 5.0 Reference Manual :: 16 Replication]]

We will use MySQL replication to keep the MySQL user data on the smarthosts
in sync with the data held on the main IMAP server.

These instructions are mainly adapted from the MySQL manual.

***** Configure the master

 :: /etc/mysql/my.cnf:

    server-id		= 1
    log_bin		= /var/log/mysql/mysql-bin.log
    expire_logs_days	= 10
    max_binlog_size	= 100M
    binlog_do_db	= mail

sudo service mysql restart

# Enter MySQL shell and create a user with replication privileges.
# NB: Use only ASCII for the <password>
mysql -u root -p

    GRANT REPLICATION SLAVE ON *.* TO 'slave_user'@'localhost' IDENTIFIED BY '<password>';
    FLUSH PRIVILEGES;
  
***** Configure the slave
****** Set up an SSH tunnel 

We begin by setting up an SSH tunnel from the slave to the master, as described [[Configuring an SSH tunnel between two hosts][above]].

****** Preparing steps to take on master

# Make a database dump.

mysql -u root -p

    USE mail;
    FLUSH TABLES WITH READ LOCK;
    quit;

mysqldump -u root -p --opt mail > mydump.sql

# Now, transfer this file to the slave.  After you have transferred the file,
# delete all copies except the one on the slave.

# Save the output of the SHOW MASTER STATUS COMMAND.
mysql -u root -p

    SHOW MASTER STATUS;
    unlock tables;
    quit;

****** Slave configuration

# Create a new temporary directory.
# NOTE: It has to be outside of /tmp so the replication is not screwed up on e.g. power outage.
        
TMP_DIR=/var/lib/mysql/tmp
sudo mkdir $TMP_DIR
sudo chown mysql:mysql $TMP_DIR
sudo chmod 0750 $TMP_DIR

 :: /etc/mysql/my.cnf

    tmpdir		= /var/lib/mysql/tmp
    # Note that the server-id must be different on all hosts
    server-id		= 2
    relay-log		= mysqld-relay-bin

sudo service mysql restart

# Enter the MySQL shell and create the database:

mysql -u root -p

    CREATE DATABASE mail;
    quit;
  
mysql -u root -p --database=mail < mydump.sql
  
# [[http://dev.mysql.com/doc/refman/5.0/en/change-master-to.html][12.5.2.1. CHANGE MASTER TO Syntax]]
# NOTE: fill in these values using output from SHOW MASTER STATUS; above
# NOTE: filling this in my.cnf is deprecated

mysql -u root -p

    SLAVE STOP;

    CHANGE MASTER TO
    MASTER_HOST='127.0.0.1',
    MASTER_PORT=1949,
    MASTER_USER='slave_user',
    MASTER_PASSWORD='<password>', MASTER_LOG_FILE='mysql-bin.000013', MASTER_LOG_POS=98;

    START SLAVE;
    show slave status\G

# If it seems OK, just:

    quit;

*** Configuring the main IMAP server
**** Install packages

sudo aptitude install postfix postfix-mysql

**** /etc/postfix/main.cf

TODO: add file contents

**** Setting up the MDA

# squeeze has dovecot-1.2. upgrade notes:
# - we might want to upgrade to their sieve (instead of cmusieve)
# - we want to add the -s flag to deliver in master.cf

***** Installing

sudo aptitude install dovecot-imapd

***** Configuring


:: /etc/dovecot/dovecot.conf

    protocol lda {
      # Address to use when sending rejection mails.
      postmaster_address = postmaster@fripost.org
    
      # Hostname to use in various parts of sent mails, eg. in Message-Id.
      # Default is the system's real hostname.
      hostname = imap.fripost.org
    
      # Support for dynamically loadable plugins. mail_plugins is a space separated
      # list of plugins to load.
      #mail_plugins =
      #mail_plugin_dir = /usr/lib/dovecot/modules/lda
    
      # Binary to use for sending mails.
      sendmail_path = /usr/lib/sendmail
    
      # UNIX socket path to master authentication server to find users.
      auth_socket_path = /var/run/dovecot/auth-master
    
      # Enabling Sieve plugin for server-side mail filtering
      mail_plugins = cmusieve
    }

    [...]

      ## dovecot-lda specific settings
      ##
      socket listen {
        master {
          path = /var/run/dovecot/auth-master
          mode = 0600
          user = xxx # User running Dovecot LDA
          #group = mail # Or alternatively mode 0660 + LDA user in this group
        }
      }

:: /etc/postfix/master.cf

    dovecot   unix  -       n       n       -       -       pipe
      flags=DRhu user=xxx:xxx argv=/usr/lib/dovecot/deliver -f ${sender} -d ${recipient} -n
    

:: /etc/postfix/main.cf

    virtual_transport = dovecot
    dovecot_destination_recipient_limit = 1

http://wiki.dovecot.org/LDA/Postfix
http://www.tehinterweb.co.uk/roundcube/#pisieverules
**** Test delivery

sudo mkdir -p /home/mail/virtual/fripost.org/
mysql -u root -p

    INSERT INTO mailbox (username,password,name,maildir,domain)
    VALUES ('exempel@fripost.org','test666','Exempelanvändare','fripost.org/exempel/Maildir/','fripost.org');

sudo /etc/init.d/postfix restart

echo "test at `date`"|mail -s "test" exempel@fripostorg

**** Configuring dovecot

sudo aptitude install dovecot-imapd

:: /etc/dovecot/dovecot.conf

# Note: These settings are already in the file but commented out or set to other
#       values.

:HIDDEN:
protocols = imaps
protocol imap {
	ssl_listen = *:993
}
disable_plaintext_auth = yes
mail_location = maildir:/home/mail/virtual/%d/%u/Maildir

# Set this to something that works for the Maildirs
first_valid_uid = XXX
first_valid_gid = XXX

# Allow clients to be fancy if they want to
mechanisms = plain cram-md5

#passdb pam <--- comment this stuff out

# uncomment this stuff
passdb sql {
  args = /etc/dovecot/dovecot-sql.conf
}

#userdb passwd  <--- comment this stuff out

# uncomment this stuff
userdb sql {
   args = /etc/dovecot/dovecot-sql.conf
}

# Do not needlessly run as root
user = nobody
:END:

:: /etc/dovecot/dovecot-sql.conf

:HIDDEN:
driver = mysql
connect = host=127.0.0.1 port=3306 user=XXX password=XXX dbname=mail

# Salted MD5
default_pass_scheme = SMD5

password_query = SELECT username AS user, password FROM mailbox WHERE username = '%u' AND domain = '%d'

# replace XXX with relevant numbers for the system
user_query = SELECT concat('/home/mail/virtual/',maildir) AS mail, XXX AS uid, XXX AS gid FROM mailbox WHERE username = '%u' AND domain = '%d'
:END:

sudo /etc/init.d/dovecot restart

# Provided there is a user, you should now be able to login using any IMAP
# client.

**** Making sure the services are not started at boot [might not be needed]
sudo update-rc.d -n dovecot stop 2 3 4 5 .
sudo update-rc.d -n postfix stop 2 3 4 5 .
*** Configuring a new smarthost to relay e-mail to the main IMAP server
**** Overview

We relay mail from our smarthosts to the main IMAP server.

This is to avoid having a single poin of failure and to separate concerns. The
IMAP server then only needs to deal with authenticated clients and the
smarthosts.

**** Prerequisites 

Before this can work we must make sure that:
- the MySQL replication is working
- there is an SSH tunnel for the smtp

If they are both setup, we can configure postfix on the smarthost to relay
emails through the tunnel.

**** Configuration files

TODO: add the necessary configuration files

*** Configuring the outgoing SMTP
**** Anonymize the senders
If RoudCube automatically anonymize the sender (by simply shortening the trace), it's not the case (by default) for SquirrelMail, or when clients connect via ESMTP/ESMTPS/ESMTPA/ESMTPSA. Here are a couple of traces we want to obfuscate, to prevent the recicipient and/or the intermediate SMTP relays to track the sender.

Received: from localhost (machine.example.org [127.0.0.1])
        by example.org (Postfix) with ESMTP id C9DAB841F4
        for <guilhem@fripost.org>; Thu, 22 Mar 2012 16:27:56 +0100 (CET)
Received: from example.org ([127.0.0.1])
        by localhost (machine.example.org [127.0.0.1]) (amavisd-new, port 10024)
        with ESMTP id 8onAXWOvImDh for <guilhem@fripost.org>;
        Thu, 22 Mar 2012 16:27:56 +0100 (CET)
Received: from webmail.example.org (localhost [IPv6:::1])
        by example.org (Postfix) with ESMTP id 3ADAB8243D
        for <guilhem@fripost.org>; Thu, 22 Mar 2012 16:27:56 +0100 (CET)
Received: from 192.168.1.5
        (SquirrelMail authenticated user guilhem)
        by webmail.example.org with HTTP;
        Thu, 22 Mar 2012 16:27:56 +0100

Received: from localhost (machine.example.org [127.0.0.1])
        by example.org (Postfix) with ESMTP id 2D1098243D
        for <guilhem@fripost.org>; Thu, 22 Mar 2012 16:36:36 +0100 (CET)
Received: from example.org ([127.0.0.1])
        by localhost (machine.example.org [127.0.0.1]) (amavisd-new, port 10024)
        with ESMTP id Hr2J-eRTN0jI for <guilhem@fripost.org>;
        Thu, 22 Mar 2012 16:36:35 +0100 (CET)                                                                                                           
Received: from client.example.org (client.machine.org [192.168.1.1])                                                                                    
        (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
        (Client CN "client.machine.org", Issuer "machine.org" (not verified))
        by machine.org (Postfix) with ESMTPS id DA22981B95
        for <guilhem@fripost.org>; Thu, 22 Mar 2012 16:36:35 +0100 (CET)
Received: (nullmailer pid 5057 invoked by uid 0);
        Thu, 22 Mar 2012 15:36:34 -0000

Received: from localhost (machine.example.org [127.0.0.1])
        by example.org (Postfix) with ESMTP id DBAFE816BB
        for <guilhem@fripost.org>; Thu, 22 Mar 2012 14:48:01 +0100 (CET)
Received: from example.org ([127.0.0.1])
        by localhost (machine.example.org [127.0.0.1]) (amavisd-new, port 10024)
        with ESMTP id Upen4QhYpKf4 for <guilhem@fripost.org>;
        Thu, 22 Mar 2012 14:48:01 +0100 (CET)
Received: from client.example.org (client.example.org [192.168.1.2])
        (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
        (Client CN "", Issuer "" (not verified))
        (Authenticated sender: guilhem)
        by guilhem.org (Postfix) with ESMTPSA id 40284804F5
        for <guilhem@fripost.org>; Thu, 22 Mar 2012 14:48:01 +0100 (CET)
Received: by machine@example.org (Postfix, from userid 1000)
        id 1D24F41747; Thu, 22 Mar 2012 14:48:00 +0100 (CET)

(The first one was sent using a SquirrelMail; The second using ESMTPS; And the third using ESMTPSA).
If we are to hide the sender, we could simply clean the trace (like RoundCube does) when the mail leaves the server. However, some aggressive mailfilters may reject the mail since the trace is incomplete (if RoundCube hides the history I guess it doesnt' happen that often, but who knows...).

Another option would be to clean the trace and to simply add a fake field to pretend that the mail is sent from localhost by the user nobody:
    Received: by example.org (Postfix, from userid 65535)
            id 2C537816BB; Thu, 22 Mar 2012 14:08:45 +0100 (CET)
This possible by adding "smtp_header_checks = regexp:$config_directory/smtp_header_checks" in the main.cf, with a suitable file "smtp_header_check" in the Postfix configuration directory.

Yetan other option is not to hide the trace, but rather forge it to pretend that the connections ESMTP/... are coming from localhost. This way we are not hiding the fast that a client has logged in using a valid certificate, and in case of an SMTP relay, the early part of the trace (before it entered our Postfix) remains unchanged. For example, the third trace would become:

Received: from [127.0.0.1] (localhost [127.0.0.1])
        (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
        (Client CN "", Issuer "" (not verified))
        (Authenticated sender: guilhem)
        by example.org (Postfix) with ESMTPSA id 40284804F5
        for <guilhem@fripost.org>; Thu, 22 Mar 2012 14:48:01 +0100 (CET)
Received: by client.example.org (Postfix, from userid 1000)
        id 1D24F41747; Thu, 22 Mar 2012 14:48:00 +0100 (CET)

(the other field remaining unchanged). This is also possible using smtp_header_checks. In that case, the corresponding file would contain the following rexep, forging the header by pretending that the sender has EHLO'ed from localhost:

  /^Received:\s+from (\S+)\s+\(\S+\s+\S+\)(.*\sby example\.org \(Postfix\)\s+with E?SMTP(S|A|SA)\W.*)$/
    REPLACE Received: from [127.0.0.1] (localhost [127.0.0.1])${2}

You can try out the regexp using "postmap -h -q - regexp:smtp_header_checks < email" (email can also be a bunch of traces).

DISCLAIMER: The regexp probably needs tests (especially for multiple hops, in case of relaying SMTPs). Also, note that the hostname of the client has not been obfuscated in the above trace (and that will break the path if the client has a routable hostname that doesn't point to the SMTP server!). However, this line has been added by the client itself, so it's his/her responsability to masquerade it I suppose. In the same way, the CN and Issuer of the client's certificate may help to track him/her down. Maybe we should forge it as well?

** Configuring the webserver

sudo apt-get install apache2

sudo a2enmod ssl rewrite

:: /etc/apache2/ports.conf

    <IfModule mod_ssl.c>
      NameVirtualHost *:443
    </IfModule>

:: /etc/apache2/conf.d/security

    ServerTokens Prod

*** Roundcube

**** Installing roundcube

# Add the backports repository first, to make sure we're running a somewhat more
# current version than the one currently in stable.

:: /etc/apt/sources.list

    deb http://backports.debian.org/debian-backports squeeze-backports main

sudo apt-get install roundcube

:: /etc/php5/apache2/php.ini

    log_errors = Off
    post_max_size = 25M
    upload_max_filesize = 25M
    tmp_dir = FIXME

:: /etc/roundcube/main.inc.php  ## checked for roundcube 0.5.4+dfsg-1~bpo60+1

    # Use caching
    $rcmail_config['enable_caching'] = TRUE;

    # fripost.org specific
    $rcmail_config['force_https'] = TRUE;
    $rcmail_config['default_host'] = 'ssl://imap.fripost.org';
    $rcmail_config['imap_auth_type'] = 'plain';
    $rcmail_config['username_domain'] = 'fripost.org';

    # use IP for extra paranoia
    $rcmail_config['ip_check'] = true;

    # Locale settings
    $rcmail_config['language'] = 'sv_SE';
    $rcmail_config['date_long'] = 'Y-m-d.Y H:i';

    $rcmail_config['product_name'] = 'Fripost';

    # IMAP Folders (I guess these were changed for compatibility with SquirrelMail)
    $rcmail_config['drafts_mbox'] = 'INBOX.Drafts';
    $rcmail_config['junk_mbox'] = 'INBOX.Junk';
    $rcmail_config['sent_mbox'] = 'INBOX.Sent';
    $rcmail_config['default_imap_folders'] = array('INBOX', 'INBOX.Drafts', 'INBOX.Sent', 'INBOX.Junk', 'Trash');
    $rcmail_config['create_default_folders'] = TRUE;

    # timezone
    $rcmail_config['timezone'] = 'CET';
 
    # compose html formatted messages by default
    $rcmail_config['htmleditor'] = TRUE;


**** Installing custom logo

wget https://fripost.org/images/logo2011_webmail.png
LOGO="logo2011_webmail.png"
sudo mv /var/lib/roundcube/skins/default/images/roundcube_logo.png /var/lib/roundcube/skins/default/images/roundcube_logo2.png
sudo mv $LOGO /var/lib/roundcube/skins/default/images/roundcube_logo.png
sudo chmod 0644 /var/lib/roundcube/skins/default/images/roundcube_logo.png

**** Adding a custom message on login page

Before this

: <roundcube:object name="preloader" images="  

in 

:: /usr/share/roundcube/skins/default/templates/login.html

    <div style="margin: 20px;"/>

    <div style="max-width: 45em; margin: 0px auto; border: dotted 3px red; padding:1em;">
    
    <h3>Important message</h3>
    
    <p align="left"><strong>Mon Feb 13 12:55:30 CET 2012</strong> </p>
    <p>
    Lorem ipsum dolor sit amet, consectetur adipiscing
    elit. Pellentesque molestie, velit vel tristique iaculis, massa diam viverra
    arcu, sit amet pellentesque dui enim vitae ipsum.</p>
    
    <p>J. Random Hacker</p>
    
    </div>

*** ikiwiki

- sudo apt-get install ikiwiki

- Add separate ikiwiki user

[[http://rtime.felk.cvut.cz/~sojka/blog/using-ikiwiki-with-gitolite/][Link: Integration with ikiwiki]]

*** gitolite and gitweb

# Note: incomplete steps

sudo apt-get install gitolite

sudo dpkg-reconfigure gitolite

  :: /var/lib/gitolite/.gitolite.rc

    $REPO_UMASK = 0027;       # gets you 'rwxr-x---'

# Add the repositories/users to gitolite
# This is mostly self-explanatory, but begin on your local workstation:

git clone gitolite@githost:gitolite-admin

cd gitolite-admin

... make edits

git push

# Push all repositories

cd myrepo

git push --all gitolite@githost:myrepo

git push --tags gitolite@githost:myrepo

# Add the gitweb user to gitolite

sudo apt-get install gitweb

sudo usermod -a -G gitolite www-data

sudo /etc/init.d/apache2 stop

sudo /etc/init.d/apache2 start

# Add repositories to gitweb

sudo ln -s /var/lib/gitolite/repositories/myrepo.git /var/cache/git/myrepo.git

... etc

# Make sure one can checkout the repository via http

[[http://www.kernel.org/pub/software/scm/git/docs/howto/setup-git-server-over-http.txt][Git docs]]

sudo su gitolite

cd /var/lib/gitolite/repositories/myrepo.git
git update-server-info
mv hooks/post-update.sample hooks/post-update

  :: /etc/apache2/sites-available/default

    AliasMatch ^/pub(/.*\.git)(/.*)? /var/cache/git$1$2 

  :: /usr/share/gitweb/indextext.html

    För att klona ett av dessa träd, installera <a href="http:///">git</a> och kör:
    
    <blockquote><code>git clone http://git.fripost.org/pub/</code> + projektets sökväg</blockquote>
    
    <p>
    För mer information om <a href="http://www.kernel.org/pub/software/scm/git/">git</a>, se en
    <a href="http://git.or.cz/">överblick</a>, en 
    <a href="http://www.kernel.org/pub/software/scm/git/docs/gittutorial.html">tutorial</a>
     eller
    <a href="http://www.kernel.org/pub/software/scm/git/docs">manualsidorna</a>.
    </p>

# Add a description of a repository for gitweb

echo "Mötesprotokoll" > fripost-meetings.git/description


** Logging
*** Overview
We want to limit how much we log for privacy reasons. At the same time we want
to be able to debug technical problems and detect intrusions.

For the webmail, we only log messages of priority warn or higher.
*** Configuration

  :: /etc/rsyslog.conf

    *.*;auth,authpriv.none;mail.err	-/var/log/syslog

# NOTE: /var/log/mail.{err,warn} can be kept at the default
# values since they do not contain any sensitive information.
  :: /etc/logrotate.d/rsyslog

    /var/log/mail.log
    /var/log/mail.info
    {
    	rotate 3
    	daily
    	missingok
    	ifempty
    	compress
    	delaycompress
    	sharedscripts
    	postrotate
    		invoke-rc.d rsyslog reload > /dev/null
    	endscript
    }

** Necessary stuff to fix for security
*** Bacula for backups
Also has tripwire-like capabilities.
*** OSSEC

*** Firewall rules
TODO: Add nice rules.

** Ideas for improved security

*** Monitoring



* Hardening
** Overview

The [[http://www.debian.org/doc/manuals/securing-debian-howto/][Securing Debian Manual]] is the definitive reference for Debian security.

These are just some quick notes for easy access to the administrators.
** ntp
# Let's be overly paranoid... ;-)

:: /etc/ntp.conf

-restrict -4 default kod notrap nomodify nopeer noquery
-restrict -6 default kod notrap nomodify nopeer noquery
+restrict default ignore
+restrict -6 default ignore

** rkhunter

sudo aptitude install rkhunter

sudo rkhunter -c --nomow --rwo

:: /etc/rkhunter.conf

    MAIL-ON-WARNING=admin@fripost.org

    ALLOWHIDDENDIR=/dev/.udev
    ALLOWHIDDENDIR=/dev/.initramfs
    ALLOWHIDDENDIR=/etc/.git

    ALLOWHIDDENFILE=/etc/.gitignore
    ALLOWHIDDENFILE=/etc/.etckeeper

    # something like: (adapt port as needed)
    INETD_ALLOWED_SVC=127.0.0.1:2000
    
    # in case whitelisting is needed, use something like:
    # (whitespace important)
    APP_WHITELIST=" openssl:0.9.8g sshd:4.7p1 "

:: /etc/default/rkhunter

    REPORT_EMAIL="admin@fripost.org"
    NICE="19"

# testing:

sudo rkhunter -c --nomow --rwo



* NEED TO KNOW FOR SERVER ADMINS

** Procedure for restarting mistral (the VPS)

1. There is one password which has to be provided at boot. This is given to our
   VPS host provider via some insecure means of communication.

2. When the server is booted, this password is changed.

3. The partition on /home/mail is then mounted. A separate password is provided
   for this.

4. Once the partition is mounted, dovecot and postfix may be started.

** Document your changes

The latest version of this document is always available at:

    git clone http://git.fripost.org/pub/fripost-docs.git

To get commit access, contact admin@fripost.org with your request.

** Use etckeeper

We keep /etc in a git repository using the tool etckeeper. This makes it
possible to use standard git commands in /etc, e.g. `git log'. `etckeeper' has
the benefit of keeping track of file permissions, which git by itself will not.

Every time you make changes to any files in /etc, you are encouraged to commit
them using a descriptive commit message.

$ etckeeper commit "postfix: relay messages to remote hosts via smtp"

If you do not commit your changes, they will be automatically committed.  This
is not ideal, since this means other administrators might have to guess as to
why changes were being made and by whom.  Please try to avoid putting your
co-administrators in this uncomfortable position.

** Use Cluster SSH

This pretty much sums it up:

"ClusterSSH controls a number of xterm windows via a single graphical console
window to allow commands to be interactively run on multiple servers over an ssh
connection."

** Use fripost-tools

We have written some tools to make administration tasks easier. They can be
found at:

    git clone git://github.com/skangas/fripost-tools.git