Category Archives: Linux HOWTO

Linux HOWTO

Configuring a Secure Mail Server on CentOS 6

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Introduction

As you know, Mail Server tutorials are all over the internet. So if you stumbled upon mine, then you were like me trying to assemble one based on how others do it to save reading the manual. A mail server is NOT a walk through the park like some other servers are (such as Web, Database, etc). They can be very complicated to master; and frankly, when you’re short on time, it’s easier to just get one going right away. Don’t dismiss the need to learn how it works once you’ve set it up otherwise you may not know how to recover from a unexpected situation. But instead, learn about how it works (and how to further tweak it) after the deadlines have been met. Besides, your boss will be impressed when you show him your successful results sooner then later.

You’re reading this blog because your needs were/are similar to what mine were:

  • You’re looking for an automated solution to installing a mail server with little effort because you’re on a tight deadline.
  • You want a central configuration point; you want everything to be easy to maintain after it’s all set up.
  • You want everything to just work the first time and you want to leave the figuring it out part to the end.
  • Package management and version control is incredibly important to you.

Here is what my tutorial will be focused on:

  • A Database Backend (PostgreSQL) giving you central configuration. This tutorial focuses on version 8.4 because that is what ships with CentOS and Red Hat. But most (if not all) of this tutorial should still work fine if you choose to use version 9.x of the database instead.
  • Spam Control (SpamAssasin v3.3.x, Amavisd-new v2.8, and Clam AntiVirus v0.98) gives you some spam and anti-virus control. I’ve been looking into DSPAM but haven’t implemented it yet. I figure I’ll make a part 2 to this blog once i get around to working with it and mastering it’s setup.
  • Dovecot Pigeonhole v2.0.x provides you a way of routing mail in the users inbox based on it’s content. You can key off of certain content within a received message and mark it as spam, or flag it as important because it was sent by a certain individual, etc. It basically gives you the ability to custom some of the post processing of a received message that passed through all the other checks (spam, anti-virus, etc).
  • Security Considered
  • Mail Delivery Agent (MDA) (DoveCot v2.0.x):
    • Secure POP3 (POP3S) Access
    • Secure IMAP (IMAPS) Access
    • WebMail (RoundCube) Access
Message Delivery Agent Configuration
MDA Configuration
  • Mail Transport Agent (MTA) (PostFix v2.6.x): Secure SMTP (SMTPS)
Mail Transport Agent
MTA Configuration
  • Web Based Administration (PostFixAdmin v2.3.6). Life is made easier when you don’t have to do very much once everything has been set up. Run your server like an ISP would:
    • Virtual Domain Administration: Add/Remove as many as you want
    • Unlimited Virtual Aliases (or restrict if you want) per domain
    • Unlimited Mailboxes (or restrict if you want) per domain
    • Administrative Delegation: Grant enough privileges to another administrator who only has rights to his/her domain you granted them access to.
    • Away on Vacation Support (automatic replies)
Central Configuration
Central Configuration

Please note the application versions identified above as this tutorial focuses specifically on only them. One big issue I found while researching how to set up a mail server was that the other tutorials I found didn’t really mention the software versions they were using. Hence, when I stumbled upon these old article(s) with new(er) software, it made for quite a painful experience when things didn’t work.

Please also note that other tutorials will imply that you setup one feature at a time. Then test it to see if it worked correctly before moving on to the next step. This is no doubt the proper way to do things. However, I’m just going to give it all to you at once. If you stick with the versions and packages I provide… If you follow my instructions, it will just work for you the first time. Debugging on your end will be a matter of tracing back to see what step you missed.

I tried to make this tutorial as cookie cutter(ish) as I could. Therefore you can literally just copy and paste what I share right to your shell prompt and the entire setup will be automated for you.

Hurdles

Just to let you know, I had many hurdles in order to pull this feat off. They were as follows:

  • postfix as shipped with CentOS and in the EPEL repository is not compiled with PostgreSQL support. I had to recompile this package as well just to enable this extra database support.
  • postfixadmin in the EPEL repository has qwirks I wasn’t happy with. I needed to fix a php error that kept coming up. I needed to adjust the database schema and permissions as well as fixing the Vacation Notification feature. I also did not want the mandatory MySQL dependency; so I removed that too.
  • perl Yes… that’s right, I had to patch perl :(. I had to recompile it due to a bug that I don’t belive was correctly addressed. In a nutshell, prior to my custom rebuild, perl-devel would haul in absolutely every development package including kernel headers and the GCC compiler. In the past the perl-devel package could be installed by itself providing us some tools spamassassin and amavisd-new depended on. You’re welcome to use the official version of perl over the one I recompiled; but be prepared to have a ton of compilation tools and source code in your production environment. This is not something I wanted at all. Interestingly enough; after the developers at RedHat said they wouldn’t tackle the issue of rolling their changes back, they seem to be entertaining this new guy’s request who’s asking for a similar alternative. So who knows, maybe newer versions of perl will accommodate mail servers again! 🙂
  • This blog itself was a massive hurdle. There are just so many configuration files and important points to account for that I found it easier to package my own rpm (nuxref-templates-mxserver) containing a series of configuration templates. The templates themselves took a while to construct in such a way that they could all be used together.

Installation

The following seven steps below will get you up and running.

Step 1 of 7: Setup Your Environment

This is the key to my entire blog; it’s going to make all of the remaining steps just work the first time for you. All; I repeat All of the steps below (after this one) assume that you’ve set this environment up. You will need to reset up your environment at least once before running through any of the remaining steps below or they will not work.

Make sure you hook up with my repository and then install all of the necessary packages:

# You'll need to be hooked up to my repository for
# the installation to be this simple. Make sure to
# visit: http://nuxref.com/nuxref-repository/

# You should use yum priorities (if you're not already) to
# eliminate version problems later, but if you intend on 
# just pointing to my repository and not the others, then you'll
# be fine.
yum install -y yum-plugin-priorities

################################################################
# Install our required products
################################################################
yum install -y 
       --enablerepo=nuxref 
       --enablerepo=nuxref-shared 
           postgresql-server postgresql 
           php-pgsql php-imap php-mcrypt php-mbstring  
           dovecot dovecot-pgsql dovecot-pigeonhole 
           clamav amavisd-new spamassassin 
           postfix postfix-perl-scripts 
           roundcubemail postfixadmin 
           nuxref-templates-mxserver

# Choose between NginX or Apache
## NginX Option (a) - This one is my preferred choice:
yum install -y 
       --enablerepo=nuxref 
       --enablerepo=nuxref-shared 
           nginx php-fpm

## Apache Option (b):
yum install -y 
       --enablerepo=nuxref 
       --enablerepo=nuxref-shared 
            httpd php

# Make sure your build of Postfix supports PostgreSQL
# execute the following to see: 
postconf -c /etc/postfix -m | 
   egrep -q '^pgsql$' && echo "Supported!" || 
      echo "Not Supported!"

# If it's not supported then you ran into the first of many
# problems I had. It also means you didn't haul in my version
# from the previous command.  This can happen if you already had
# postfix installed on your machine and it's of a newer version
# then what I'm hosting. Your options at this point is to either
# uninstall your copy of postfix and install mine or recompile 
# your version of postfix (but this time with PostgreSQL support).

# Setup Default Timezone for PHP. For a list of supported
# timezones you can visit here: http://ca1.php.net/timezones
TIMEZONE="America/Montreal"
sed -i -e "s|^[ t]*;*(date.timezone[ t]*=).*|1 $TIMEZONE|g" /etc/php.ini

################################################################
# Setup PostgreSQL (v8.4)
################################################################
# The commands below should all work fine on a PostgreSQL v9.x
# database too; but your mileage may vary as I've not personally
# tested it yet.

# Only init the database if you haven't already. This command
# could otherwise reset things and you'll loose everything.
# If your database is already setup and running, then you can
# skip this line
service postgresql initdb

# Now that the database is initialized, configure it to trust
# connections from 'this' server (localhost)
sed -i -e 's/^[ t]*(local|host)([ t]+.*)/#12/g' 
    /var/lib/pgsql/data/pg_hba.conf
cat << _EOF >> /var/lib/pgsql/data/pg_hba.conf
# Configure all local database access with trust permissions
local   all         all                               trust
host    all         all         127.0.0.1/32          trust
host    all         all         ::1/128               trust
_EOF

# Make sure PostgreSQL is configured to start up each time
# you start up your system
chkconfig --levels 345 postgresql on

# Start the database now too because we're going to need it
# very shortly in this tutorial
service postgresql start

To simplify your life, I’ve made the configuration of all the steps below reference a few global variables. The ones identified below are the only ones you’ll probably want to change. May I suggest you paste the below information in your favorite text editor (vi, emacs, etc) and adjust the variables to how you want them making it easier to paste them back to your terminal screen.

# Identify the domain name of your server here
DOMAIN=nuxref.com
# Setup what you want to be your Administrative email account
# Note: This does 'NOT' have to be of the same domain even though
#       thats how I set it up to be. Don't worry if the email
#       address doesn't exist, because when you're all done
#       following this blog, you'll be able to create it!
ADMIN=hostmaster@$DOMAIN

# The following is only used for our SSL Key Generation
COUNTRY_CODE="7K"
PROV_STATE="Westerlands"
CITY="Lannisport"
SITE_NAME="NuxRef"

Now for the rest of the global configuration; There really should be no reason to change any of these values (but feel free to). It’s important that you paste the above information (tailored to your liking’s) as well as the below information below to your command line interface (CLI) of the server you wish to set up.

# PostgreSQL Database
PGHOST=localhost
PGPORT=5432
PGNAME=system_mail
# This is the Read Only access user (or very limited access)
PGROUSER=mailreader
PGROPASS=mailreader
# This is for administration
PGRWUSER=mailwriter
PGRWPASS=mailwriter

# VHost Mail Directory
VHOST_HOME=/var/mail/vhosts
VHOST_UID=5000
# No real reason to make them differ
# but define tis variable anyway for
# below configuration to work
VHOST_GID=$VHOST_UID

# RoundCube Configuration
MXHOST=$PGHOST
PGRQNAME=system_roundcube
PGRQUSER=roundcube_user
PGRQPASS=roundcube_pass

# This is where our templates get installed to make your life
# incredibly easy and the setup to be painless. These files are
# installed from the nuxref-templates-mxserver RPM package you
# installed above. If you do not have this RPM package then you
# must install it or this blog simply won't work for you.
# > yum install --enablerepo=nuxref nuxref-templates-mxserver
NUXREF_TEMPLATES=/usr/share/nuxref

Once all of this has been set you can proceed to do any of the below steps! Keep in mind that if you decide to change any of the variables above, you may need to redo every single step identified below.

Step 2 of 7: System Preparation

First off, Make sure you’ve set up your environment correctly (defined in Step 1 above) or you will have problems with the outcome of this step!
General:

# Create vmail user; this will be a secure user no one else has
# permissions to that we can lock and keep our mail private
# from any prying eyes of people who have or gain access to our
# server.
useradd -u $VHOST_UID -d /var/mail/vhosts -M -s /sbin/nologin vmail
mkdir -p  /var/mail/vhosts/
chown vmail.vmail /var/mail/vhosts/
chmod 700 /var/mail/vhosts/

# Create a clam user we can preform our anti-virus scans as
usermod -G amavis clam

# Fix ClamD Sock Reference
sed -i -e 's|/var/spool/amavisd/clamd.sock|/var/run/clamav/clamd.sock|g' /etc/amavisd/amavisd.conf

# Fix Amavis Directory Permission
chmod 1770 /var/spool/amavisd/tmp/
# Amavis Domain Configuration
sed -i -e '/NuxRef BulletProofing/d' 
       -e "s/(# $myhostname.*)/1n$myhostname = 'mail.$DOMAIN'; # NuxRef BulletProofing/g" /etc/amavisd/amavisd.conf
sed -i -e "s/^($mydomain[ t]*=[ t]*).*$/1'$DOMAIN';/g" /etc/amavisd/amavisd.conf

# Generate SSL Keys (if you don't have any already) that we
# will secure all our inbound and outbound mail as.
openssl req -nodes -new -x509 -days 730 -sha256 -newkey rsa:2048 
   -keyout /etc/pki/tls/private/$DOMAIN.key 
   -out /etc/pki/tls/certs/$DOMAIN.crt 
   -subj "/C=$COUNTRY_CODE/ST=$PROV_STATE/L=$CITY/O=$SITE_NAME/OU=IT/CN=$DOMAIN"

# Permissions; protect our Private Key
chmod 400 /etc/pki/tls/private/$DOMAIN.key

# Permissions; protect our Public Key
chmod 444 /etc/pki/tls/certs/$DOMAIN.crt

Create PostgreSQL Mail Database:

# Optionally Eliminate Reset Database.
/bin/su -c "/usr/bin/dropdb -h $PGHOST -p $PGPORT $PGNAME 2>&1" postgres &>/dev/null
/bin/su -c "/usr/bin/dropuser -h $PGHOST -p $PGPORT $PGRWUSER 2>&1" postgres &>/dev/null
/bin/su -c "/usr/bin/dropuser -h $PGHOST -p $PGPORT $PGROUSER 2>&1" postgres &>/dev/null

# Create Read/Write User (our Administrator)
echo "Enter the role password of '$PGRWPASS' when prompted"
/bin/su -c "/usr/bin/createuser -h $PGHOST -p $PGPORT -S -D -R $PGRWUSER -P 2>&1" postgres

# Create Read-Only User
echo "Enter the role password of '$PGROPASS' when prompted"
/bin/su -c "/usr/bin/createuser -h $PGHOST -p $PGPORT -S -D -R $PGROUSER -P 2>&1" postgres

# Create our Database and assign it our Administrator as it's owner
/bin/su -c "/usr/bin/createdb -h $PGHOST -p $PGPORT -O $PGRWUSER $PGNAME 2>&1" postgres 2>&1

# Secure and protect a temporary file to work with
touch /tmp/pgsql.postfix.schema.sql
chmod 640 /tmp/pgsql.postfix.schema.sql
chown root.postgres /tmp/pgsql.postfix.schema.sql

# the below seems big; but will work fine if you just copy and
# it as is right to your terminal: This will prepare the SQL
# statement needed to build your mail server's database backend
sed -e '/^--?/d' 
    -e "s/%PGROUSER%/$PGROUSER/g" 
    -e "s/%PGRWUSER%/$PGRWUSER/g" 
    -e "s/%DOMAIN%/$DOMAIN/g" 
        $NUXREF_TEMPLATES/pgsql.postfix.template.schema.sql > 
          /tmp/pgsql.postfix.schema.sql

# load DB
/bin/su -c "/usr/bin/psql -h $PGHOST -p $PGPORT -f /tmp/pgsql.postfix.schema.sql $PGNAME 2>&1" postgres 2>&1
# cleanup
/bin/rm -f /tmp/pgsql.postfix.schema.sql

Step 3 of 7: Setup our Mail Transfer Agent (MTA): Postfix

First off, Make sure you’ve set up your environment correctly (defined in Step 1 above) or you will have problems with the outcome of this step!

################################################################
# Configure Postfix (MTA)
################################################################
# Create backup of configuration files
[ ! -f /etc/postfix/main.cf.orig ] && 
   cp /etc/postfix/main.cf /etc/postfix/main.cf.orig
[ ! -f /etc/postfix/master.cf.orig ] && 
   cp /etc/postfix/master.cf /etc/postfix/master.cf.orig

# Directory to store our configuration in
[ ! -d /etc/postfix/pgsql ] && 
    mkdir -p /etc/postfix/pgsql

# Secure this new directory since it will contain passwords
# information
chmod 750 /etc/postfix/pgsql
chown root.postfix /etc/postfix/pgsql

# Now using our templates, build our SQL files:
for FILE in relay_domains.cf 
            transport_maps.cf 
            virtual_alias_maps.cf 
            virtual_domains_maps.cf 
            virtual_mailbox_limit_maps.cf 
            virtual_mailbox_maps.cf
do
    sed -e "/^#?/d" 
        -e "s/%PGROUSER%/$PGROUSER/g" 
        -e "s/%PGROPASS%/$PGROPASS/g" 
        -e "s/%PGHOST%/$PGHOST/g" 
        -e "s/%PGNAME%/$PGNAME/g" 
            $NUXREF_TEMPLATES/pgsql.postfix.template.$FILE > 
                /etc/postfix/pgsql/$FILE
done

# main.cf
sed -e "/^#?/d" 
    -e "s/%DOMAIN%/$DOMAIN/g" 
    -e "s|%VHOST_HOME%|$VHOST_HOME|g" 
    -e "s/%VHOST_UID%/$VHOST_UID/g" 
    -e "s/%VHOST_GID%/$VHOST_GID/g" 
        $NUXREF_TEMPLATES/pgsql.postfix.template.main.cf > 
            /etc/postfix/main.cf

# master.cf
cat $NUXREF_TEMPLATES/pgsql.postfix.template.master.cf > 
   /etc/postfix/master.cf

# Run the newaliases command to generate /etc/aliases.db
newaliases

# Vacation Support
echo "autoreply.$DOMAIN vacation:" > /etc/postfix/transport
postmap /etc/postfix/transport

# Update to latest Spam Assassin Rules/Filters
sa-update
# Update to latest Antivirus
freshclam

# Setup Auto-Cron Entries (so future antivirus updates
# can just be automatic).
sed -i -e '//etc/cron.hourly/d' /etc/crontab
sed -i -e '//etc/cron.daily/d' /etc/crontab
sed -i -e '//etc/cron.weekly/d' /etc/crontab
sed -i -e '//etc/cron.monthly/d' /etc/crontab
cat << _EOF >> /etc/crontab
  01 * * * * root run-parts /etc/cron.hourly 
  02 4 * * * root run-parts /etc/cron.daily 
  22 4 * * 0 root run-parts /etc/cron.weekly 
  42 4 1 * * root run-parts /etc/cron.monthly
_EOF

# Enable our Services On Reboot
chkconfig --levels 345 spamassassin on
chkconfig --levels 345 clamd on
chkconfig --levels 345 clamd.amavisd on
chkconfig --levels 345 amavisd on
chkconfig --levels 345 postfix on

# Start all of our other services if they aren't already
service spamassassin start
service clamd start
service amavisd start
service clamd.amavisd start

# Restart our postfix service to on our new configuration
service postfix restart

Step 4 of 7: Setup our Mail Delivery Agent (MDA): Dovecot

First off, Make sure you’ve set up your environment correctly (defined in Step 1 above) or you will have problems with the outcome of this step!

################################################################
# Configure Dovecot (MDA)
################################################################
# Create backup of configuration files
[ ! -f /etc/dovecot/dovecot.conf.orig ] && 
   cp /etc/dovecot/dovecot.conf /etc/dovecot/dovecot.conf.orig

# dovcot.conf
sed -e "/^#?/d" 
    -e "s/%DOMAIN%/$DOMAIN/g" 
    -e "s|%VHOST_HOME%|$VHOST_HOME|g" 
    -e "s/%VHOST_UID%/$VHOST_UID/g" 
    -e "s/%VHOST_GID%/$VHOST_GID/g" 
        $NUXREF_TEMPLATES/pgsql.dovecot.template.dovecot.conf > 
            /etc/dovecot/dovecot.conf

# Create our Sieve Directories
[ ! -d /var/lib/sieve/users ] && 
   mkdir -p /var/lib/sieve/users
[ ! -d /var/lib/sieve/before.d ] && 
   mkdir -p /var/lib/sieve/before.d
[ ! -d /var/lib/sieve/after.d ] && 
   mkdir -p /var/lib/sieve/after.d
chown -R vmail.vmail /var/lib/sieve
chmod 750 /var/lib/sieve

# Dovecot PostgreSQL Configuration
for FILE in dovecot-sql.conf 
            dovecot-dict-user-quota.conf 
            dovecot-dict-domain-quota.conf
do
   sed -e "/^#?/d" 
       -e "s|%VHOST_HOME%|$VHOST_HOME|g" 
       -e "s/%VHOST_UID%/$VHOST_UID/g" 
       -e "s/%VHOST_GID%/$VHOST_GID/g" 
       -e "s/%PGROUSER%/$PGROUSER/g" 
       -e "s/%PGROPASS%/$PGROPASS/g" 
       -e "s/%PGHOST%/$PGHOST/g" 
       -e "s/%PGNAME%/$PGNAME/g" 
           $NUXREF_TEMPLATES/pgsql.dovecot.template.$FILE > 
               /etc/dovecot/$FILE
   # permissions
   chmod 640 /etc/dovecot/$FILE
   chown root.dovecot /etc/dovecot/$FILE
done

# Warning Message when mailbox is almost full
sed -e "/^#?/d" 
    -e "s/%DOMAIN%/$DOMAIN/g" 
        $NUXREF_TEMPLATES/pgsql.dovecot.template.mail-warning.sh > 
            /usr/libexec/dovecot/mail-warning.sh

# Make Script Executable
chmod 755 /usr/libexec/dovecot/mail-warning.sh

# Ensure Dovecot starts after each system reboot:
chkconfig --levels 345 dovecot on

# Start Dovecot (otherwise restart it if it's already running)
service dovecot status && service dovecot restart || service dovecot start

Step 5 of 7: Setup Postfix Admin

First off, Make sure you’ve set up your environment correctly (defined in Step 1 above) or you will have problems with the outcome of this step!

################################################################
# Configure PostfixAdmin
################################################################
sed -e "/^//?/d" 
    -e "s/%DOMAIN%/$DOMAIN/g" 
    -e "s/%ADMIN%/$ADMIN/g" 
    -e "s/%PGHOST%/$PGHOST/g" 
    -e "s/%PGNAME%/$PGNAME/g" 
    -e "s/%PGRWUSER%/$PGRWUSER/g" 
    -e "s/%PGRWPASS%/$PGRWPASS/g" 
        $NUXREF_TEMPLATES/pgsql.postfixadmin.template.config.local.php > 
            /etc/postfixadmin/config.local.php

# Protect file since it contains passwords
chmod 640 /etc/postfixadmin/config.local.php
chown root.apache /etc/postfixadmin/config.local.php

# Vacation Auto-respond Support
sed -e "/^#?/d" 
    -e "s/%DOMAIN%/$DOMAIN/g" 
    -e "s/%PGROUSER%/$PGROUSER/g" 
    -e "s/%PGROPASS%/$PGROPASS/g" 
    -e "s/%PGHOST%/$PGHOST/g" 
    -e "s/%PGNAME%/$PGNAME/g" 
        $NUXREF_TEMPLATES/pgsql.postfixadmin.template.vacation.conf > 
            /etc/postfixadmin/vacation.conf

# Protect file since it contains passwords
chmod 640 /etc/postfixadmin/vacation.conf
chown root.vacation /etc/postfixadmin/vacation.conf

# Log Rotation
cat << _EOF > /etc/logrotate.d/postfix-vacation
/var/log/vacation.log {
        missingok
        notifempty
        create 644 vacation root
}
_EOF

Now you can setup NginX to host your administration; in the below example, I set up https://postfixadmin.<your.domain>/ to go to the postfixadmin page.

# Create dummy favicon.ico for now (silences some log entries)
touch /usr/share/postfixadmin/favicon.ico

# PostfixAdmin NginX Configuration
sed -e "/^#?/d" 
    -e "s/%DOMAIN%/$DOMAIN/g" 
        $NUXREF_TEMPLATES/nginx.postfixadmin.template.conf > 
            /etc/nginx/conf.d/postfixadmin.conf

# You may have to bump php-fpm to be safe (if it's not already running)
service php-fpm status 2>/dev/null && service php-fpm restart || service php-fpm start
# make sure it starts on every reboot too:
chkconfig php-fpm --level 345 on
# Restart NginX if it's not already
service nginx status 2>/dev/null && service nginx restart || service nginx start
chkconfig nginx --level 345 on

Once you’re complete that, you’re now ready to access the administrator interface and set up a new account. Simply visit https://postfixadmin.<your.domain>/setup.php. The templates I provided will set the system password to admin. You’ll need to always enter this value prior to creating an account below.
PostfixAdmin Setup
Once you’re done creating an account, just change the setup.php script to read-only as a security precaution. You can preform every other action you’ll ever need using the account you already created.

################################################################
# Disable Future System Administrator Creation
################################################################
chmod 600 /usr/share/postfixadmin/setup.php

# later on, you can re-enable the setup.php file to create a new
# account in the distant future by just typing:
#
# chmod 644 /usr/share/postfixadmin/setup.php
#

You can simply access https://postfixadmin.<your.domain>/ now (without the setup.php) and login using the new administrator you created.

Step 6 of 7: Setup Roundcube

First off, Make sure you’ve set up your environment correctly (defined in Step 1 above) or you will have problems with the outcome of this step!

################################################################
# Configure RoundCube Mailer
################################################################
# RoundCube NginX Configuration
sed -e "/^#?/d" 
    -e "s/%DOMAIN%/$DOMAIN/g" 
        $NUXREF_TEMPLATES/nginx.roundcubemail.template.conf > 
            /etc/nginx/conf.d/roundcubemail.conf

# Optionally Eliminate Reset RoundCube Database
/bin/su -c "/usr/bin/dropdb -h  $PGHOST -p $PGPORT $PGRQNAME 2>&1" postgres &>/dev/null
/bin/su -c "/usr/bin/dropuser -h $PGHOST -p $PGPORT $PGRQUSER 2>&1" postgres &>/dev/null

# Create RoundCube Admistrator User
echo "Enter the role password of '$PGRQPASS' when prompted"
/bin/su -c "/usr/bin/createuser -h $PGHOST -p $PGPORT -S -D -R $PGRQUSER -P 2>&1" postgres 2>&1

# Create our Database and assign it our Administrator as it's owner
/bin/su -c "/usr/bin/createdb -h $PGHOST -p $PGPORT -O $PGRQUSER $PGRQNAME 2>&1" postgres 2>&1
/usr/bin/psql -h $PGHOST -p $PGPORT -U $PGRQUSER $PGRQNAME -f /usr/share/doc/roundcubemail-0.9.5/SQL/postgres.initial.sql

# Configure Roundmail
sed -i -e "s|(^[ t]*$rcmail_config[[']db_dsnw['"]][ t]*=).*$|1 'pgsql://$PGRQUSER:$PGRQPASS@$PGHOST/$PGRQNAME';|g" /etc/roundcubemail/db.inc.php
sed -i -e "s|(^[ t]*$rcmail_config[[']default_host['"]][ t]*=).*$|1 'ssl://$MXHOST:993';|g" /etc/roundcubemail/main.inc.php
sed -i -e "s|(^[ t]*$rcmail_config[[']smtp_server['"]][ t]*=).*$|1 'tls://$MXHOST';|g" /etc/roundcubemail/main.inc.php
sed -i -e "s|(^[ t]*$rcmail_config[[']smtp_user['"]][ t]*=).*$|1 '%u';|g" /etc/roundcubemail/main.inc.php
sed -i -e "s|(^[ t]*$rcmail_config[[']smtp_pass['"]][ t]*=).*$|1 '%p';|g" /etc/roundcubemail/main.inc.php

# Some extra Roundmail options I preferred:
sed -i -e "s|(^[ t]*$rcmail_config[[']identities_level['"]][ t]*=).*$|1 3;|g" /etc/roundcubemail/main.inc.php
sed -i -e "s|(^[ t]*$rcmail_config[[']quota_zero_as_unlimited['"]][ t]*=).*$|1 true;|g" /etc/roundcubemail/main.inc.php
sed -i -e "s|(^[ t]*$rcmail_config[[']htmleditor['"]][ t]*=).*$|1 1;|g" /etc/roundcubemail/main.inc.php
sed -i -e "s|(^[ t]*$rcmail_config[[']preview_pane['"]][ t]*=).*$|1 true;|g" /etc/roundcubemail/main.inc.php

# You may have to bump php-fpm to be safe (if it's not already running)
service php-fpm status 2>/dev/null && service php-fpm restart || service php-fpm start
# make sure it starts on every reboot too:
chkconfig php-fpm --level 345 on
# Restart NginX if it's not already
service nginx status 2>/dev/null && service nginx restart || service nginx start
chkconfig nginx --level 345 on

You can simply access https://roundcube.<your.domain>/ now and access any mailboxes you configured. Just remember to tell your users that they must specify their full email address as their username.

Each mailbox you create using PostfixAdmin you’ll be able to access with your Roundcube webpage.

Step 7 of 7: Security

If you aren’t familiar with Fail2Ban; now would be an excellent time to learn about it. I wrote a blog about securing your CentOS system a while back and encourage you to read it. At the very least, read the section on Fail2Ban. The below explains how you can protect yourself from brute force.

# Monitor for multiple failed SASL Logins into postfix
cat << _EOF > /etc/fail2ban/filter.d/postfix-sasl.conf
[Definition]
failregex = (?i): warning: [-._w]+[<HOST>]: SASL (?:LOGIN|PLAIN|(?:CRAM|DIGEST)-MD5) authentication failed(: [A-Za-z0-9+/ ]*)?$
ignoreregex =
_EOF
# Monitor for multiple failed postfixadmin logins
cat << _EOF > /etc/fail2ban/filter.d/postfixadmin-auth.conf
[Definition]
failregex = ^<HOST> -.*POST.*login.php HTTP[^ t]+ 500$
ignoreregex =
_EOF

# Now in /etc/fail2ban/jail.conf you will want the following:
cat << _EOF >> /etc/fail2ban/jail.conf
[dovecot-iptables]
enabled  = true
filter   = dovecot
backend  = polling
action   = iptables[name=dovecot, port=110,143,993,995, protocol=tcp]
           sendmail-whois[name=dovecot, dest=root, sender=fail2ban@$DOMAIN]
logpath  = /var/log/mail.log

[sasl-iptables]
enabled  = true
filter   = postfix-sasl
backend  = polling
action   = iptables[name=sasl, port=25,587, protocol=tcp]
           sendmail-whois[name=sasl, dest=root, sender=fail2ban@$DOMAIN]
logpath  = /var/log/mail.log

[roundcube-iptables]
enabled  = true
filter   = roundcube-auth
backend  = polling
action   = iptables[name=RoundCube, port="http,https"]
           sendmail-whois[name=RoundCube, dest=root, sender=fail2ban@$DOMAIN]
logpath  = /var/log/roundcubemail/errors

[pfixadmadmin-iptables]
enabled  = true
filter   = postfixadmin-auth
backend  = polling
action   = iptables[name=PostfixAdmin, port="http,https"]
           sendmail-whois[name=PostfixAdmin, dest=root, sender=fail2ban@$DOMAIN]
logpath  = /var/log/nginx/postfixadmin.access.log
_EOF

You will want to additionally add the following to your iptables /etc/sysconfig/iptables:

#---------------------------------------------------------------
# Web Traffic (for PostfixAdmin and RoundCube)
#---------------------------------------------------------------
# Allow non-encrypted port so we can redirect these users to the
# encrypted version.  It's just a nicer effect to support
# redirection
-A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 443 -j ACCEPT

#---------------------------------------------------------------
# SMTP /Message Transfer Agent Communication
#---------------------------------------------------------------
-A INPUT -m state --state NEW -m tcp -p tcp --dport 465 -j ACCEPT

#---------------------------------------------------------------
# IMAP 
#---------------------------------------------------------------
-A INPUT -m state --state NEW -m tcp -p tcp --dport 993 -j ACCEPT

#---------------------------------------------------------------
# POP3
#---------------------------------------------------------------
-A INPUT -m state --state NEW -m tcp -p tcp --dport 995 -j ACCEPT

Useful Commands When Running Your Mail Server

  • doveconf -a: Display Dovecot configuration
  • postconf -n: Display Postfix configuration
  • postqueue -p: Display mail queue information

Sometimes when first playing with quotas, you may or may not want to recalculate them against a user. This can be done as follows:

#  Recalculate a specific users quota
doveadm quota recalc -u foobar@your.domain.com

# Or you can do this and recalculate ALL user quotas
doveadm quota recalc -A

# You will also want to run the following command if you decide
# to recalculate someone (or all) in your database:
# UPDATE domain_quota SET bytes=sq.sb, messages=sq.sm 
#   FROM (SELECT 'your.domain.com',
#           sum(bytes) as sb, sum(messages) as sm from quota2 WHERE
#            username like '%@your.domain.com') AS sq 
#   WHERE domain = 'your.domain.com';

Note: If you delete a mailbox for a specified domain, remember to manually remove: /var/mail/vhosts/domain/user

So… That’s it? Now I’m done?

Yes and No… My blog pretty much hands over a working mail server with little to no extra configuration needed on your part. But to properly accept mail from other people around the world, you will need:

  1. This mail server (ideally) must be accessible to the internet via a static IP address. This means that if you’re hosting this at home, the IP address your ISP provides you may not work (Dynamic IP vs Static IP). That said; a lot of ISPs can offer you a static IP if you don’t already have one for little (to no) extra cost.
  2. Your own domain name (if you don’t have an official one already) because you can’t have an email@your.domain.com if your.domain.com isn’t publicly recognized.
  3. A Mail Exchange (MX) Record that points to your new mail server by via it’s accessible IP on the internet. This is the only way the outside world will be able to send mail back to you; this step is not required if the only thing you’re doing is sending email out.

    Most Domain Registars allow you to set your own MX record (GoDaddy.com, NameCheap.com) which can simply be entered right from their webpage with little to no effort. If you’re paying someone else to host your websites for the domain you own, then most likely they have the MX record already pointing to them. You may need to open a support ticket (or call them) and tell them you want the MX record changed to point back to your own server instead or forward it.

Please keep in mind that there are risks involved with running your own mail server. You can get yourself temporarily (or permantenly) blacklisted if you’re not careful. Once you’re blacklisted, you’ll have a very hard time getting other mail servers on the internet to accept your emails for delivery. Blacklisting occurs when mail servers (which you will now be interacting with) detect abuse. In most cases, the mail server administrator (this is YOU) won’t even know you’re abusing other peoples servers. The abuse will start under your nose from emails that originated from your system by those you given mailboxes too. In fact, once your domain is blacklisted; it can be a pain in the @$$ to get de-listed later. A Blacklisted domain’s emails usually never reaches their intended recipient. Instead, they are immediately flagged as spam and sent to the deleted items (by the remote server). The configuration I provided considers most of the cases, but you still need to consider:

  • Don’t create mailboxes for people that you know intend to use it for derogatory purposes or for the intentions of spamming others. Hence; don’t allow users to send out hundreds of thousands of emails a day to a massive distribution on a regular bases even if it’s meaningful mail. Consider that the same stuff that you don’t like in your inbox is the same stuff that nobody else likes in theirs either. 🙂
  • Don’t allow your mail server to relay mail from untrusted sources. Hence; make sure you only allow users you create accounts for to send mail from your server.
  • Throttle all outbound mail delivery to each of their relay locations. With respect to the first point, even if you have to send massive amounts of mail from your system on a regular basis, do it in small batches. This way you won’t overwhelm the remote servers accepting your mail you want delivered.

If you followed my blog and are using the settings I put in place, then you’re already configured for the last 2 options above. The first option is governed by your own decisions.

No system is bulletproof; disaster can always strike when you’re least expecting it. To cover yourself, always consider backups of the following:

  • Your PostgreSQL Database: This is where all of your mail configuration is for both your MTA and MDA. You definitely do not want to lose this. May I suggest you reference my other blog entry here where I wrote a really simple backup/restore tool for a PostgreSQL database.
  • /etc/postfixadmin/*: Your Postfix Admin flat file configuration allowing you to centrally manage everything via a webpage.
  • /etc/postfix/*: Your Postfix flat file configuration which defines the core of your MTA. It’s configuration allows you to centrally manage everything else through the Postfix Administration website.
  • /etc/roundcube/*: Your Roundcube flat file configuration which allowing users to check their mail via a webpage you host.
  • /etc/dovecot/*: Your Dovecot flat file configuration which defines the core of your MDA. It’s configuration allows you to centrally manage everything through the Postfix Administration website.
  • /var/mail/vhosts/*: All of your user’s mailboxes are defined here. This is a vast storage of unread and read mail that resides on your server.

Oct 20th, 2014 Security Update: Handles The Poodle SSLv3 Exploit
Last week a security exploit was found specifically targeting web hosting making use of the SSLv3 (see here for details) protocol. Previously, the NginX templates (residing in nuxref-templates-mxserver version 1.0.1 or less) I provided did not protect you from this vulnerability. As a result; earlier readers of this blog entry may be susceptible to a man-in-the-middle attack. I just recently posted an update to the nuxref-templates-mxserver (v1.0.2) which will automatically cover any new bloggers building a mail server. For the previous readers, you just need to make 2 changes to correct yourself of this exploit:

  1. Open up /etc/nginx/conf.d/roundcubemail.conf and /etc/nginx/conf.d/postfixadmin.conf and change this: 
       ssl_ciphers HIGH:!ADH:!MD5;
   ssl_prefer_server_ciphers on;
   ssl_protocols SSLv3;
   ssl_session_cache shared:SSL:1m;
   ssl_session_timeout 15m;

    to this:

       ssl_session_timeout  5m;
   ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
   ssl_ciphers 'ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-DSS-AES128-GCM-SHA256:kEDH+AESGCM:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA:ECDHE-ECDSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-DSS-AES128-SHA256:DHE-RSA-AES256-SHA256:DHE-DSS-AES256-SHA:DHE-RSA-AES256-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128:AES256:AES:DES-CBC3-SHA:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!RC4:!MD5:!PSK';
   ssl_prefer_server_ciphers on;
   ssl_session_cache  builtin:1000  shared:SSL:10m;

    This information was based on a great blog entry on securing your NginX configuration found here.

  2. Finally you will want to reload your NginX configuration so it takes on the new updates you applied: 
    # Reload NginX
service nginx reload

What about Apache?

Apache is a perfectly fine alternative solution as well! I simply chose NginX because it is much more lightweight approach. In fact, PostfixAdmin and RoundCube mail already come with Apache configuration out of the box located in /etc/httpd/conf.d/. Thus, if you simply start up your Apache instance (service httpd start), you will be hosting its services right away. Please keep in mind that the default (Apache) configuration does not come with all the SSL and added security I provided with the NginX templates. Perhaps later on, I will update the template rpm to include an Apache secure setup as well.

Credit

This blog took me a very (,very) long time to put together and test! The repository hosting alone now accommodates all my blog entries up to this date. If you like what you see and wish to copy and paste this HOWTO, please reference back to this blog post at the very least. It’s really all I ask.

Repository

This blog required me to set up my own repository of which I was thinking that some people might want me to continue to maintain. Such as fetching and applying the latest security updates after testing them first for the continued promise of stability. Personally, I believe I may be setting up a new can of worms for myself by offering this service because bandwidth costs money and updates cost time. But I’ll share it publicly and see how things go anyway.

If you’d like me to continue to monitor and apply updates as well as hosting the repository for long terms, please consider donating or offering a mirror server to help me out! This would would be greatly appreciated!

Sources

This blog could not have been made possible without the tons of resources that I used. Some of these resources including other peoples blogs too which I picked and chose approaches they took.

Software Resources

Linux HOWTO

Backing Up and Restoring Your PostgreSQL Database

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Introduction

As a Developer or even a System Administrator, experiencing database corruption is a scary thing. Usually when something you’re responsible fails… it fails hard. It’s important to always make frequent backups of your database(s) your in charge of. The internet is filled with solutions and one liners you can consider. But there is a lot of contradiction everywhere too as each site tells you how it should be done. Personally, I’m not going to tell you the way I do it is the correct way or not. But I will tell you it works, and it’s saved me in numerous occasions.

I’m lazy, and when I look for solutions online, I always hope someone is just going to spell it right out for me. It’s so much easier when someone else does all the work; but usually that’s wasn’t the case for me. Stack Overflow is fantastic for getting the quick 1 liners you need to build your solution, but I prefer automation. I don’t want to remember all of the different options one tool has from another. I want simplicity because when something fails, I don’t want to learn the complicated steps to do a database restoration.

As a strong supporter of PostgreSQL, I want to provide the solution I use to hopefully speed along someone else’s research in the future. I can’t stress enough also that if you aren’t taking regular backups of databases you are responsible for, then you really should reconsider and at use the scripts defined below.

Jun 28th, 2016 Update
I packaged pgnux_backup, pgnux_restore and pgnux_kickusers into an RPM to simplify things:
RPM: pgnux-1.0.3-1.el6.nuxref.noarch.rpm
Source: pgnux-1.0.3-1.el6.nuxref.src.rpm

Those who use CentOS/Red Hat 7 can get them here:
RPM: pgnux-1.0.3-1.el7.nuxref.noarch.rpm
Source: pgnux-1.0.3-1.el7.nuxref.src.rpm

These RPMs can also be fetch from my nuxref repository.

The rest of this blog contains a simplified version of the content found in the attached RPMs but should still suit the needs of most!

Database Backup

Assuming you you are the global system administrator responsible for a PostgreSQL database and have root privileges, here is a simple backup script you can use:

#!/bin/bash
# Author: Chris Caron <lead2gold at gmail.com>
# Name: pgnux_backup
# Description: Preform a backup of one ore more PostgreSQL Database(s)
# Returns: 0 on success, a non-zero value if a failure occurred
# Syntax: pgnux_backup [db1 [db2 [db3 [...]]]
#
# Note: If no database is specified to be backed up, then all of
#       databases hosted by the postgresql instance are used.

##################################
# Define some simple variables
##################################
PGENGINE=/usr/bin
PGPORT=5432
PGHOST=localhost
DUMPDIR=/var/pgbackup

##################################
# System Tweaks
##################################
# if COMPRESSION is enabled, then all database backups are
# gzipped to save space.  The trade off is more cpu power will
# be used to generate your backups and they will take longer
# to create.  But you can save yourself significant amounts of
# disk space.  Set this value to 0 if you do not wish to use
# compression. COMPRESSION can be set to a value between 0 and
# 9 where a setting of 0 is used to disable it.
# Please keep in mind also, that if you choose to use
# compression, the PostgreSQL restores will be a bit slower since
# the data needs to be first uncompressed before it can be
# reloaded.
COMPRESSION=6

# For SELinux we need to use 'runuser' not 'su'
if [ -x /sbin/runuser ]; then
    SU=/sbin/runuser
else
    SU=/bin/su
fi

# Safety Check
if [ $(whoami) != 'root' ]; then
   echo "Error: You must be 'root' to use this script."
   exit 1
fi

# List of databases you wish to back up by default.  If you
# leave this blank, then the system will automatically detect
# all of the databases hosted by the PostgreSQL instance.
#
# You can use Space, Tab or some form of white space delimiter
# between each database you specify if you need to specify more
# than one.
# If nothing is specified on the command line (when this script
# is called, then this is the default list that will be used in
# it's place.
DBLIST=""

# If anything was specified on the command line; we over-ride it here
[ ! -z "$@" ] && DBLIST="$@"

# Capture the current time to make it easy to locate our backups later
SNAPTIME=$(date +'%Y%m%d%H%M%S')

# Build DBLIST if it isn't already defined:
[ -z "$DBLIST" ] && DBLIST=$($SU -l postgres -c "$PGENGINE/psql 
                          -p $PGPORT -h $PGHOST -lt | 
                   awk 'NF >=5 { print $1}' | 
                    egrep -v '^[ t]*(template[0|1]||)')

# Create our backup directory if it doesn't already exist
[ ! -d $DUMPDIR ] && mkdir -p $DUMPDIR

# Ensure our directory is protected from prying eyes
chmod 770 $DUMPDIR
chown root.postgres $DUMPDIR

# Backup our Database Globals (exit on failure)
$SU -l postgres -c "$PGENGINE/pg_dumpall --globals-only 
   -p $PGPORT -h $PGHOST | 
   gzip -c > $DUMPDIR/${SNAPTIME}-globals.sql.gz"
if [ $? -ne 0 ]; then
   echo -n "$(date +'%Y-%m-%d %H:%M:%S') - $$ - ERROR - "
   echo "Failed to dump system globals; backup aborted."
   exit 2
fi

# Protect our backup and ensure the user postgres user can manage
# this file if need be.
chmod ug+rw "$DUMPDIR/${SNAPTIME}-globals.sql.gz" &>/dev/null
chown postgres.root $DUMPDIR/${SNAPTIME}-globals.sql.gz &>/dev/null

FAIL_COUNT=0
# Iterate over our database list and perform our backup:
for DBNAME in $DBLIST; do
   echo -n "$(date +'%Y-%m-%d %H:%M:%S') - $$ - INFO - "
   echo "Dumping database '$DBNAME' ..."
   PGBKUP=
   PGFLAGS="-p $PGPORT -h $PGHOST --create --oids --format=t --verbose"
   if [ $COMPRESSION -gt 0 ]; then
      # Use Compression
      PGBKUP=$SNAPTIME-$DBNAME.db.gz
      $SU -l postgres -c "$PGENGINE/pg_dump $PGFLAGS $DBNAME | 
                 gzip -cq$COMPRESSSION > $DUMPDIR/$PGBKUP"
      RETVAL=$?
   else
      # Do not compres (flag is not set to 1)
      PGBKUP=$SNAPTIME-$DBNAME.db
      $SU -l postgres -c "$PGENGINE/pg_dump $PGFLAGS 
                 --file=$DUMPDIR/$PGBKUP $DBNAME"
      RETVAL=$?
   fi
   if [ $RETVAL -eq 0 ]; then
      echo -n "$(date +'%Y-%m-%d %H:%M:%S') - $$ - INFO - "
      echo "Backup Complete: $PGBKUP"
      chmod ug+rw $DUMPDIR/$PGBKUP &>/dev/null
      chown postgres.root $DUMPDIR/$PGBKUP &>/dev/null
   else
      [ -f $DUMPDIR/$PGBKUP ] && 
          rm -f $DUMPDIR/$PGBKUP
      echo -n "$(date +'%Y-%m-%d %H:%M:%S') - $$ - ERROR - "
      echo "Backup Failed: $PGBKUP"
      let FAIL_COUNT+=1
   fi
done

if [ $FAIL_COUNT -ne 0 ]; then
   exit 1
fi
exit 0

Database Restore

Backups are one thing, but the ability to restore is another. This script pairs with the above and will allow you to restore different points in time.

#!/bin/bash
# Author: Chris Caron <lead2gold at gmail.com>
# Name: pgnux_restore
# Description: Preform a restore of one ore more PostgreSQL Database(s)
# Returns: 0 on success, a non-zero value if a failure occurred
# Syntax: pgnux_restore <database_name> [snapshot_time]
#
# Note: This script will not work if people are connected to the
#       databases in question you are trying to restore.
 
##################################
# Define some simple variables
##################################
PGENGINE=/usr/bin
PGPORT=5432
PGHOST=localhost
DUMPDIR=/var/pgbackup
 
# How many backups in the past to list when no restore
# has taken place
HISTORY=10
 
# Specify a keyword that when in place of the <database_name>
# it triggers all databases for specified snapshot time to be
# restored including database system globals. Set this to
# 'nothing' if you want the restore to do a global restore every
# time (might be dangerous)
# The below allows you to type 'pgnux_restore --' to restore
# everything.
RESTORE_ALL_KEYWORD="--"

# For SELinux we need to use 'runuser' not 'su'
if [ -x /sbin/runuser ]; then
    SU=/sbin/runuser
else
    SU=/bin/su
fi

# Safety Check
if [ $(whoami) != 'root' ]; then
   echo "Error: You must be 'root' to use this script."
   exit 1
fi

# Not worth continuing if there is no dump directory
if [ ! -d $DUMPDIR ]; then
   echo -n "$(date +'%Y-%m-%d %H:%M:%S') - $$ - ERROR - "
   echo "Directory '$DUMPDIR' does not exist."
   exit 2
fi
  
# Capture Database(s) and allow for delimiters to separate more
# then one. Keep in mind that the first database specified will
# be the one used to detect the SNAPTIME if one isn't specified
DBLIST=$(echo "$1" | sed -e 's/[,:+%!&]/ /g')
 
# Take the value specified on the command line (argument 2)
shift
_SNAPTIME=$(echo "$@" | sed -e 's/[^0-9]//g')
SNAPTIME=
if [ -z "$_SNAPTIME" ]; then
   # Fetch most recent backup time
   SNAPTIME=$(find -L $DUMPDIR -maxdepth 1 -mindepth 1 
        -type f -regex ".*/[0-9]+-.*.(db|db.gz)$" 
        -exec basename {} ; | 
        sed -e 's/^([0-9]+)-(.*).(db|db.gz)$/1/g' | 
        sort -r -n | uniq | head -n1)
   if [ -z "$SNAPTIME" ]; then
      echo -n "$(date +'%Y-%m-%d %H:%M:%S') - $$ - ERROR - "
      echo "No backups detected."
      exit 2
   fi
fi
 
# Initialize Globals Loaded Flag 
GLOBALS_LOADED=1
if [ "$DBLIST" == "$RESTORE_ALL_KEYWORD" ]; then
   # Now we build a list of the databases based on the
   # snapshot time specified
   DBLIST=$(find -L $DUMPDIR -maxdepth 1 -mindepth 1 
      -type f -regex ".*/$SNAPTIME-.*.(db|db.gz)$" 
      -exec basename {} ; | 
      sed -e 's/^[0-9]+-(.*).(db|db.gz)$/1/g')
   GLOBALS_LOADED=0
fi
 
FAILLIST=""
RESTORE_COUNT=0
for DBNAME in $DBLIST; do
   # Toggle 'Globals Loaded Flag' if 'Restore All Keyword' found
   # This neat little trick allows you to force the restores of
   # globals associated with a specified date of the backup
   # hence: pgnux_restore --,foobar_database 2014010100000
   # would cause the globals taken at this time to be loaded
   # with the database,
   [ "$DBLIST" == "$RESTORE_ALL_KEYWORD" ] && GLOBALS_LOADED=0

   # If no Snapshot time was specified, we need to
   # keep detecting it based on the database specified
   [ -z "$_SNAPTIME" ] &&
      SNAPTIME=$(find -L $DUMPDIR -maxdepth 1 -mindepth 1 
        -type f -regex ".*/[0-9]+-$DBNAME.(db|db.gz)$" 
        -exec basename {} ; | 
        sed -e 's/^([0-9]+)-(.*).(db|db.gz)$/1/g' | 
        sort -r -n | uniq | head -n1)
   PGBKUP=$DUMPDIR/$SNAPTIME-$DBNAME.db

   if [ $GLOBALS_LOADED -eq 0 ] && 
      [ -f $DUMPDIR/globals-$SNAPTIME.sql.gz ]; then
      echo -n "$(date +'%Y-%m-%d %H:%M:%S') - $$ - INFO - "
      echo -n $"Restoring Database Globals ..."
         $SU -l postgres -c "gunzip 
             -c $DUMPDIR/globals-$SNAPTIME.sql.gz | 
             $PGENGINE/psql -a -p $PGPORT -h $PGHOST"
      # Toggle Flag
      GLOBALS_LOADED=1
   fi
 
   # Detect Compression
   if [ -f $PGBKUP.gz ]; then
      echo -n "$(date +'%Y-%m-%d %H:%M:%S') - $$ - INFO - "
      echo $"Uncompressing Database $DBNAME ($SNAPTIME)..."
      gunzip -c $PGBKUP.gz > $PGBKUP
      if [ $? -ne 0 ]; then
         FAILLIST="$FAILLIST $DBNAME"
         [ -f $PGBKUP ] && rm -f $PGBKUP
      fi
   fi
 
   [ ! -f $PGBKUP ] && continue
 
   echo -n "$(date +'%Y-%m-%d %H:%M:%S') - $$ - INFO - "
   echo $"Restoring Database $DBNAME ($SNAPTIME)..."
   # This action can fail for 2 reasons:
   #  1. the database doesn't exist (this is okay because we
   #     are restoring it anyway.
   #  2. Someone is accessing the database we are trying to
   #     drop.  You need to make sure you've stopped all
   #     processes that are accessing the particular database
   #     being restored or you will have strange results.
   $SU -l postgres -c "$PGENGINE/dropdb 
          -p $PGPORT -h $PGHOST $DBNAME" &>/dev/null
   # use -C & -d 'template1' so we can bootstrap off of the
   # 'template1' database. Note, that this means we are bound
   # by the character encoding of 'template1' (default is UTF-8)
   $SU -l postgres -c "$PGENGINE/pg_restore -e -v -p $PGPORT 
                   -C -d template1 -h $PGHOST $PGBKUP"
   [ $? -ne 0 ] && FAILLIST="$FAILLIST $DBNAME" || 
        let RESTORE_COUNT+=1
   [ -f $PGBKUP.gz ] && [ -f $PGBKUP ] && rm -f $PGBKUP
done
  
# Spit a readable list of databases that were not recovered if
# required.
if [ ! -z "$FAILLIST" ]; then
   for DBNAME in $FAILLIST; do
      echo "Warning: $DBNAME ($SNAPTIME) was not correctly restored."
   done
   exit 1
elif [ $RESTORE_COUNT -eq 0 ]; then
   # Nothing was restored; now is a good time to display to the user
   # their options
   echo -n "$(date +'%Y-%m-%d %H:%M:%S') - $$ - WARNING - "
   echo $"There were no databases restored."
   echo
   # Display last X backups and the databases associated with each
   BACKUPS=$(find -L $DUMPDIR -maxdepth 1 -mindepth 1 
        -type f -regex ".*/[0-9]+-.*.(db|db.gz)$" 
        -exec basename {} ; | 
        sed -e "s/^([0-9]+)-(.*).(db|db.gz)$/1|2/g" | 
        sort -r -n | head -n$HISTORY)
   [ -z "$BACKUPS" ] && exit 1
 
   LAST_SNAPTIME=""
   printf "    %-16s %sn" "TIMESTAMP" "DATABASE(S)"
   for BACKUP in $BACKUPS; do
      SNAPTIME=$(echo $BACKUP | cut -d'|' -f1)
      DBNAME=$(echo $BACKUP | cut -d'|' -f2)
      if [ "$LAST_SNAPTIME" != "$SNAPTIME" ]; then
          printf "n%s: %s" $(echo "$SNAPTIME" | 
              sed -e 's/([0-9]{4})([0-9]{2})([0-9]{2})([0-9]{2})([0-9]{2})([0-9]{2})/1-2-3_4:5:6/g') "$DBNAME"
          LAST_SNAPTIME=$SNAPTIME
      else
         printf ", %s" "$DBNAME"
      fi
   done
   printf "n"
   exit 1
fi
exit 0

Automation

Consider creating a few crontab entries to manage backups during off hours as well as some tool that can keep your backups from growing out of control on your hard drive. Feel free to adjust the numbers as you see fit. The below assumes you copied the 2 scripts above in /usr/bin

cat << EOF > /etc/cron.d/nuxref_postgresql_backup
# Create a backup of all databases every hour
0  * * * * root /usr/bin/pgnux_backup &>/dev/null
# Only keep the last 30 days of backups (check run every hour on the 40 min mark)
40 * * * * root find /var/pgbackup -maxdepth 1 -type f -mtime +30 -delete &>/dev/null
EOF

Usage

Backups are as simple as the following:

# Backup All databases
pgnux_backup

# Backup just the foobar_database:
pgnux_backup foobar_database

# Backup just the foobar_database and the barfoo_database:
pgnux_backup foobar_database barfoo_database

Restoring requires that no one is accessing the database (if it already exists). Otherwise it’s just as easy:

# Call the script with no parameters, to see a nice list of the last 10 backups.
# This list can be really helpful because it also identifies all of the
# snapshot times that they were taken.  You need these times to preform
# restores with.
pgnux_restore

# Restore ALL databases that resided in the last database snapshot
# Caution: If you just backed up a single database on it's own last
#          time, this might be a bit unsafe to run. If you backed
#          up other databases at a different time, then they won't
#          get included in this restore. The -- also forces the
#          system globals to get reloaded as well.
pgnux_restore --

# Restore the last snapshot taken of the foobar_database
pgnux_restore foobar_database

# Restore the last snapshot taken of the foobar_database and
# barfoo_database notice we can't use space as a delimiter (like
# pgnux_backup does) only because the second argument identifies
# the snapshot time (in case you want your restore to be specific).
pgnux_restore foobar_database,barfoo_database

# With respect to the last point, this will restore a database
# snapshot further back in the past (not the latest one). This
# also assumes you have a backup at this point.  You can find
# this out by running pgnux_restore all by itself as the first
# example given above. The script will take care of the formatting
# of the time so long as you provide YYYYMMDDHHmmss in that format.
# You can stick in as many delimiters to make the time readable as
# you want. The below restore a specific database snapshot:
pgnux_restore foobar_database 2014-03-13_15:47:06

# You can restore more then one database at a specific time as
# well using the a comma (,) to delimit your databases and
# specifying the snapshot time at the end. Here is how to restore
# the foobar_database and the barfoo_database at a specific
# instance of time:
pgnux_restore foobar_database,barfoo_database 2014-03-13_15:47:06

# the -- also plays another role, it can be used to force the loading
# of the postgresql globals again when it's paired with databases
# consider the above line but with this small tweak:
pgnux_restore --,foobar_database,barfoo_database 2014-03-13_15:47:06

Catastrophic Recoveries

If worst case scenario happens, and the restore process seems to be failing you, your not out of options. As long as you’ve been taking frequent backups, there is always a way back!

Remember that restores will fail if the database is being accessed by someone else. The below is a dirty little scripted trick that boots everyone accessing your system off. It’s somewhat dangerous to do, but if restoring is your final goal, then the danger is mitigated.

#!/bin/bash
# Author: Chris Caron <lead2gold at gmail.com>
# Name: pgnux_kickusers
# Description: Kicks all users off of a PostgreSQL instance being
#              accessed.
# Syntax: pgnux_kickusers

##################################
# Define some simple variables
##################################
PGENGINE=/usr/bin
PGPORT=5432
PGHOST=localhost

# For SELinux we need to use 'runuser' not 'su'
if [ -x /sbin/runuser ]; then
    SU=/sbin/runuser
else
    SU=/bin/su
fi

# Safety Check
if [ $(whoami) != 'root' ]; then
   echo "Error: You must be 'root' to use this script."
   exit 1
fi

# Get a list of all PIDS accessing our system while kicking
# the ones we can control via the database
# PostgreSQL 9.2 and above
PIDS=$($SU -l postgres \
      -c "$PGENGINE/psql -h $PGHOST -p $PGPORT -t -E --no-align \
      -c \"SELECT pg_stat_activity.pid, pg_terminate_backend(pg_stat_activity.pid) FROM pg_stat_activity WHERE pid <> pg_backend_pid();\"" 2>/dev/null | egrep -v 't' | cut -d'|' -f1)

# PostgreSQL 9.1 and below (un-comment if this is your version):
# PIDS=$($SU -l postgres \
#       -c "$PGENGINE/psql -h $PGHOST -p $PGPORT -t -E --no-align \
#      -c \"SELECT  pg_stat_activity.procpid,pg_terminate_backend(pg_stat_activity.procpid) FROM pg_stat_activity WHERE procpid <> pg_backend_pid();\"" 2>/dev/null | egrep -v 't' | cut -d'|' -f1)

# Iterate over the left over pids that we couldn't otherwise
# handle and attempt to kick them by sending each of them a SIGTERM.
for PID in $PIDS; do
   RETRY=3
   while [ $RETRY -gt 0 ]; do
      kill $PID &>/dev/null
      ps -p $PID &>/dev/null
      if [ $? -ne 0 ]; then break; fi
      let RETRY-=1
   done
   # All PostgreSQL Documentation will tell you SIGKILL
   # is the absolute 'WORST' thing you can do.
   # The below code should only be uncommented in
   # catastrophic situations where a restore is inevitable
   # ps -p $PID &>/dev/null
   # [ $? -eq 0 ] && kill -9 $PID
done
exit 0

They can also fail if PostgreSQL data directory contents has been corrupted. Corruption can occur:

  • From a system that is experiencing harddrive failures.
  • From another processes accessing /var/lib/pgsql/data/* that shouldn’t be. Only the database itself should be modifying/accessing the contents of this directory unless you know what you’re doing.
  • From just a simple power outage. A busy system that isn’t backed up by a UPS device or redundant power sources can have it’s file system corrupted easily during a loss of power. What usually happens is PostgreSQL is writing content to the database when the power is pulled from the machine. At the end of the day, you’re left with a database that wasn’t correctly written to and in some cases can be seriously damaged from this as a result.

In some cases, the corruption can be so bad the database instance (PostgreSQL) won’t even start. Evidently, you can’t restore a working copy of a database if the service itself isn’t working for you.

Sometimes attempting to repair the write-ahead logging can help you recover. Obviously this completely depends on the type of failure you’re experiencing. /var/lib/pgsql/data/pg_xlog/* can help shed some light on this subject as well. The below script assumes your instance of PostgreSQL is stopped.

# Make sure your database is NOT running if you intend to run the below
# command:
service postgresql stop

Here is the the simple wrapper to the read-ahead write log repair:

#!/bin/bash
# Author: Chris Caron <lead2gold at gmail.com>
# Name: pgnux_repair
# Description: Simple wrapper to pg_resetxlog
# Syntax: pgnux_repair
 
##################################
# Define some simple variables
##################################
PGENGINE=/usr/bin
PGDATA=/var/lib/pgsql/data

# For SELinux we need to use 'runuser' not 'su'
if [ -x /sbin/runuser ]; then
    SU=/sbin/runuser
else
    SU=/bin/su
fi

# Safety Check
if [ $(whoami) != 'root' ]; then
   echo "Error: You must be 'root' to use this script."
   exit 1
fi

# Attempt to repair the WAL logs
$SU -l postgres -c "$PGENGINE/pg_resetxlog -f $PGDATA"

If it still doesn’t work, as a last resort consider these simple commands to bring your system back up again. Note that you should be the root user prior to preforming these steps:

# Stop the database (if it isn't already):
service postgresql stop

# Backup your configuration files
mkdir -p /tmp/postgresql_conf
cp -a /var/lib/pgsql/data/*.conf /tmp/postgresql_conf

# Destroy the database data directory. Unless you changed the
# default directory, the below command will do it:
# This is IRREVERSIBLE, be sure you have a recovery point to
# restore to before doing this otherwise you will make your
# situation worse!
find /var/lib/pgsql/ -mindepth 1 -maxdepth 1 rm -rf {} ;

# Initialize a new empty database; this will rebuild
# the /var/lib/pgsql/data directory for you
service postgresql initdb

# Restore all of your configuration you backed up above:
cp -af /tmp/postgresql_conf/*.conf /var/lib/pgsql/data/

# Just in case, for SELinux Users, make sure we're set okay
restorecon -R /var/lib/pgsql

# Start your database up
service postgresql start

# Now restore your databases using pgnux_restore and make sure you
# include the double dash '--' so that you load the system globals
# back as well:
#   pgnux_restore --,db1,db2,db3,db4,...
#
# If you've always been backing them all together, then you can
# restore them with a single command:
pgnux_restore --

# Your done! You should be back and running now and hopefully with
# minimal downtime.

Disclaimer

I can not be held responsible or liable for anything that goes wrong with your system. This blog is intended to be used as a resource only and will hopefully help you out in the time of need. These tools work for me and have been tested thoroughly using PostgreSQL v8.4 (which ships with CentOS 6.x). I have not tried any of these tools for PostgreSQL v9.x or higher and can not promise you anything, but I honestly can’t see a reason why they wouldn’t work.

Credit

Please note that this information took me several days to put together and test thoroughly. I may not blog often; but I want to re-assure the stability and testing I put into everything I intend share.

If you like what you see and wish to copy and paste this HOWTO, please reference back to this blog post at the very least. It’s really all I ask.

Linux HOWTO

Configuring and Installing VSFTPD on CentOS 6

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Introduction

FTP Servers have been around for a very long time. On could easily argue that they aren’t always the best option to choose anymore. But for those dealing with legacy systems, the FTP protocol provides one the easiest ways to share and distribute files across external systems. Despite the hate some might give the protocol; it still receives a lot a love from others just because it’s still very compatible with just about everything; heck, even web browsers such as Internet Explorer, Chrome, and Firefox (and many more) have the protocol built right into it.

In my case, I needed to set up an FTP server to help a client with some legacy software they use (and are familiar with). This blog is more or less just the steps I took to make it work in case anyone else is interested.

Security Concerns

FTP preforms all of it’s transactions in ‘plain text’ including it’s authentication. This wasn’t a problem back in 1980 when online security wasn’t an issue. This also isn’t a problem for sites offering anonymous file hosting services. But for everyone else, it pretty much leaves you susceptible to privacy issues and possible intrusions.

FTPS (not to be confused with SFTP) is a way of securing the FTP protocol for the systems that require it allowing you to eliminate the ‘plain text’ problem. But this requires the client uses software that can take advantage of it.

Some additional security concerns I wanted to consider:

  • Separate user accounts from the system ones. We don’t want people trying to guess our root password or access anyone’s home directory unless with specifically configure the server to allow it.

Setup VSFTPD

VSFTPD stands for Very Secure FTP Daemon and provides all the flexibility we need. It’s official website can be found here.

The following will set up VSFTPD into your CentOS/RedHat environment in a isolated manor. You see we want to disconnect the users that currently access your system from the users we create for VSFTPD for more flexibility and control.

# First fetch the required packages
# db4:       The Berkeley Database (Berkeley DB) which is a
#             quick and dirty way of storing our user accounts.
# db4-utils: This provides a tool we'll use to build a small user
#             database with.  Technically you can uninstall (just)
#             this package afterwards for added security after.
# openssl:   This is used to grant our FTP server FTPS support
# vsftpd:    The FTP/FTPS Daemon itself
yum -y install db4 db4-utils openssl vsftpd

# Create a password file: /etc/vsftpd/users.passwd
# This file contains all of the users you want to allow on the
# site in the structure:
# Line: Entry
#  1  | USERNAME1
#  2  | PASSWORD1
#  3  | USERNAME2
#  4  | PASSWORD2
# This below creates a simple user 'foobar' and a password
# of 'barfoo'.  This isn't the safest way to build your password
# file because it leaves a persons password set available in
# the shell history... But for the purpose of this tutorial:
echo foobar > /etc/vsftpd/users.passwd
echo barfoo >> /etc/vsftpd/users.passwd

# Protect our password file now from prying eyes:
chmod 600 /etc/vsftpd/users.passwd
chown root.root /etc/vsftpd/users.passwd

# Prepare a directory we want the foobar user to send it's files
# to. You can also just use a directory you already have in place
# or someone elses home directory.
mkdir -p /var/ftp/foobar

# Set a comfortable permission to this directory granting the ftp
# user (or any user account your later going to assign to this user
# read/write access)
chown root.ftp /var/ftp/foobar
chmod 775 /var/ftp/foobar

# Convert our plain-text password file into the Berkeley Database
# format. This is the only command that requires the db4-utils
# rpm package which you can uninstall if you want for security
# reasons after you run the below command.  You'll need to
# re-install it though if you ever want to add or update accounts
db_load -T -t hash 
   -f /etc/vsftpd/users.passwd /etc/vsftpd/virtual.users.db

# Protect our new (Berkley) database:
chmod 600 /etc/vsftpd/virtual.users.db
chown root.root /etc/vsftpd/virtual.users.db

# Prepare our virtual user directory; this is where we can
# optionally place over-riding configuration for each user
# we create in the Berkley database above.
mkdir -p /etc/vsftpd/virtual.users
chmod 700 /etc/vsftpd/virtual.users
chown root.root /etc/vsftpd/virtual.users

# Create PAM Module that points to our new database.
# Note: you do not provide the '.db' extension when creating
#       this file. The file is valid as you see it below.
cat << _EOF > /etc/pam.d/vsftpd-virtual
auth     required pam_userdb.so db=/etc/vsftpd/virtual.users
account  required pam_userdb.so db=/etc/vsftpd/virtual.users
session  required pam_loginuid.so
_EOF

# Protect our Module
chmod 644 /etc/pam.d/vsftpd-virtual
chown root.root /etc/pam.d/vsftpd-virtual

# Create an empty jail directory.  This is used for default
# configurations only. A well configured system won't even use
# this; but it's still good to have since we'll be referencing
# it in our configuration. This will become the default
# directory a user connects to if they aren't otherwise
# configured to go to another location.
mkdir -p /var/empty/vsftpd/
chown nobody.ftp /var/empty/vsftpd/
chmod 555 /var/empty/vsftpd/

# Now we want to allow FTPS support, we'll need an SSL key to
# do it with.  If you already have one, you can skip this step.
# Otherwise, the following will just generate you a self-signed
# key as a temporary solution.
openssl req -nodes -new -x509 -days 730 -sha256 -newkey rsa:2048 
   -keyout /etc/pki/tls/private/nuxref.com.key 
   -out /etc/pki/tls/certs/nuxref.com.crt 
   -subj "/C=7K/ST=Westerlands/L=Lannisport/O=NuxRef/OU=IT/CN=nuxref.com"

# Protect our Keys
chmod 400 /etc/pki/tls/private/nuxref.com.key; # Private Key
chmod 444 /etc/pki/tls/certs/nuxref.com.crt; # Public Certificate

# Create ourselves a little banner we can use to at least alert
# human intruders that they are in fact being monitored.  This
# scare tactic may or may not work, but if you ever have a breach
# of security, you may need to reference that you gave the user
# ample warning that they were violating someones rights by
# continuing.  Feel free to adjust the banner to your liking.
cat << _EOF > /etc/banner
* - - - - - - W A R N I N G - - - - - - - W A R N I N G - - - - - *
*                                                                 *
* The use of this system is restricted to authorized users. All   *
* information and communications on this system are subject to    *
* review, monitoring and recording at any time, without notice or *
* permission.                                                     *
*                                                                 *
* Unauthorized access or use shall be subject to prosecution.     *
*                                                                 *
* - - - - - - W A R N I N G - - - - - - - W A R N I N G - - - - - *
_EOF

# Protect our banner
chmod 640 /etc/banner

At this point we have our environment set up the way we want it. The next step is to create our VSFTPD configuration.

# Lets first backup original configuration file
mv /etc/vsftpd/vsftpd.conf /etc/vsftpd/vsftpd.conf.orig

# Create new configuration
cat << _EOF > /etc/vsftpd/vsftpd.conf
# --------------------------------------------------------------
# Base Configuration
# --------------------------------------------------------------
anon_world_readable_only=NO
anonymous_enable=NO
chroot_local_user=YES
hide_ids=YES
listen=YES
local_enable=YES
max_clients=10
max_per_ip=3
nopriv_user=ftp
pasv_min_port=64000
pasv_max_port=64100
session_support=NO
user_config_dir=/etc/vsftpd/virtual.users
userlist_enable=YES
use_localtime=YES
xferlog_enable=YES
xferlog_std_format=NO
log_ftp_protocol=YES
pam_service_name=vsftpd-virtual
banner_file=/etc/banner
reverse_lookup_enable=NO
# --------------------------------------------------------------
# Secure Configuration (FTPS)
# --------------------------------------------------------------
ssl_enable=YES
virtual_use_local_privs=NO
allow_anon_ssl=NO
# forcing SSL makes the FTP portion of your site disabled and it
# will only operate as FTPS.  This may or may not be what you
# want.
force_local_data_ssl=NO
force_local_logins_ssl=NO
ssl_tlsv1=YES
ssl_sslv2=NO
ssl_sslv3=NO
# Point to our certificates
rsa_cert_file=/etc/pki/tls/certs/nuxref.com.crt
rsa_private_key_file=/etc/pki/tls/private/nuxref.com.key
require_ssl_reuse=NO
ssl_ciphers=HIGH:!MD5:!ADH
# --------------------------------------------------------------
# FTP Configuration
# --------------------------------------------------------------
async_abor_enable=YES
ftp_data_port=20
connect_from_port_20=YES
# --------------------------------------------------------------
# Default Anonymous Restrictions (over-ride per virtual user)
# --------------------------------------------------------------
guest_enable=NO
guest_username=nobody
# Default home directory once logged in
local_root=/var/empty/vsftpd
# write_enabled is required if the user is to make use of any of
# the anon_* commands below
write_enable=NO
# give the user the ability to make directories
anon_mkdir_write_enable=NO
# give the user the ability delete and overwrite files
anon_other_write_enable=NO
# give the user the ability upload new files
anon_upload_enable=NO
# Give the user permission to do a simple directory listings
dirlist_enable=NO
# Give the user permission to download files
download_enable=NO
# if the user has can upload or make new directories, then this
# will be the umask applied to them
anon_umask=0002
# delete failed uploads (speaks for itself)
delete_failed_uploads=YES
_EOF

# Protect our configuration
chmod 600 /etc/vsftpd/vsftpd.conf
chown root.root /etc/vsftpd/vsftpd.conf

Technically we’re done now, but because we intentionally specified very restrictive user access rights, our foobar user we created will only connect to the /var/empty/vsftpd directory with no access rights. Therefore, our final step is to create an additional configuration file for the foobar account granting him read/write access to /var/ftp/foobar.

# The file you write to in the /etc/vsftpd/virtual.users/ 'must' be the same
# name as the user(s) you created to over-ride their permissions!
cat << _EOF > /etc/vsftpd/virtual.users/foobar
local_root=/var/ftp/foobar
# --------------------------------------------------------------
# User
# --------------------------------------------------------------
guest_enable=YES
# Set this to any system user you want
guest_username=ftp
local_root=/var/ftp/foobar
# --------------------------------------------------------------
# Permissions
# --------------------------------------------------------------
# write_enabled is required if the user is to make use of any of
# the anon_* commands below
write_enable=YES
# give the user the ability to make directories
anon_mkdir_write_enable=YES
# give the user the ability delete and overwrite files
anon_other_write_enable=YES
# give the user the ability upload new files
anon_upload_enable=YES
# Give the user permission to do a simple directory listings
dirlist_enable=YES
# Give the user permission to download files
download_enable=YES
# if the user has can upload or make new directories, then this
# will be the umask applied to them
anon_umask=0002
# delete failed uploads (speaks for itself)
delete_failed_uploads=NO
_EOF

# Protect our foobar permission file
chmod 600 /etc/vsftpd/virtual.users/foobar
chown root.root /etc/vsftpd/virtual.users/foobar

You are now complete, you can start VSFTPD at any time:

# Have VSFTPD start after each system reboot
chkconfig --level 345 vsftpd on

# Start VSFTPD if it isn't already running
service vsftpd status || service vsftpd start

It’s worth noting that if you ever change any of the configuration or add more, you will need to restart the VSFTPD server in order for the changes you made to take effect:

# Restarting the vsftpd server is simple:
service vsftpd restart

Firewall Configuration

The FTP firewall configuration can get complicated especially when the ephemeral ports it chooses to open are random (when operating it in Passive mode). If you scan through the configuration file above, you’ll see that we’ve specified this range to be between 64000 and 64100.

In a nutshell, if you choose to use/enable FTPS (which I strongly recommend you do), the firewall configuration will look like this (/etc/sysconfig/iptables):

#....
#---------------------------------------------------------------
# FTP Traffic
#---------------------------------------------------------------
-A INPUT -p tcp -m state --state NEW --dport 21 -j ACCEPT
# non-encrypted ftp connections (ip_contrack_ftp) module looks
# after these ports, however for the encrypted sessions it can't
# spy so we need to disable ip_contrack_ftp and just open the
# port range himself
-A INPUT -p tcp -m state --state NEW --dport 64000:64100 -j ACCEPT
#...

However, if (and only if) you choose not to use FTPS and strictly operate using FTP only then your configuration will look as follows:

  1. /etc/sysconfig/iptables 
    #....
#---------------------------------------------------------------
# FTP Traffic
#---------------------------------------------------------------
-A INPUT -p tcp -m state --state NEW --dport 21 -j ACCEPT
#...
  2. /etc/sysconfig/iptables-config
    This file requires you to add ip_conntrack_ftp to the variable IPTABLES_MODULES which is near the top of this file. You may also need to update /etc/sysconfig/ip6tables-config if you are using ip6; the change is the same. This keeps the entire range of 64000 to 64100 ports closed be default and through packet sniffing, they are opened on demand.
#...
IPTABLES_MODULES="ip_conntrack_ftp"
#...

If you’re not running any other modules, you can use the following one liner to update the file:

sed -i -e 's/^IPTABLES_MODULES=.*/IPTABLES_MODULES="ip_conntrack_ftp"/g' 
    /etc/sysconfig/iptables-config
sed -i -e 's/^IPTABLES_MODULES=.*/IPTABLES_MODULES="ip_conntrack_ftp"/g' 
    /etc/sysconfig/ip6tables-config

Be sure to reload your firewall configuration once you have these in place:

# Restart the firewall
service iptables restart

Fail2Ban Brute Force Configuration

The final thing you should consider if your server will be available via the internet is some bruit force prevention. I really recommend you read my blog on Securing Your CentOS 6 System, specifically my blurb on Fail2Ban which I think all systems should always have running. Fail2ban allows you to track all users hitting your FTP server and take immediate action on preventing further access to this potential intruder.

The configuration is as follows (remember to set the email to what you want it as where I’ve specified your@email.goes.here so you can be notified of any intrusions that take place.

cat << _EOF >> /etc/fail2ban/jail.conf
[my-vsftpd-iptables]

enabled  = true
filter   = vsftpd
action   = iptables[name=VSFTPD, port=ftp, protocol=tcp]
           sendmail-whois[name=VSFTPD, dest=your@email.goes.here]
logpath  = /var/log/vsftpd.log
_EOF

Be sure to reload your Fail2Ban configuration once this is done

# Restart Fail2Ban
service fail2ban restart

Test Our Configuration

Make sure you have an ftp tool installed into your environment like lftp or even a GUI based tool like FileZilla that supports both FTP and FTPS. The old Linux tool ‘ftp’ will only allow you to test the un-encrypted connection.

# Install lftp to keep things simple
yum -y install lftp

# Test our server (FTP)
[root@nuxref ~]# lftp ftp://foobar:barfoo@localhost
lftp foobar@localhost:~> pwd
ftp://foobar:barfoo@localhost
lftp foobar@localhost:~> exit

# Test our server (FTPS)
[root@nuxref ~]# lftp ftps://foobar:barfoo@localhost
lftp foobar@localhost:~> pwd
ftps://foobar:barfoo@localhost
lftp foobar@localhost:~> exit

First lets just test the basic FTP portion (plain-text):

# Connect to our server
[root@nuxref ~]# ftp localhost
Connected to localhost (127.0.0.1).
220-* - - - - - - W A R N I N G - - - - - - - W A R N I N G - - - - - *
220-*                                                                 *
220-* The use of this system is restricted to authorized users. All   *
220-* information and communications on this system are subject to    *
220-* review, monitoring and recording at any time, without notice or *
220-* permission.                                                     *
220-*                                                                 *
220-* Unauthorized access or use shall be subject to prosecution.     *
220-*                                                                 *
220-* - - - - - - W A R N I N G - - - - - - - W A R N I N G - - - - - *
220 
Name (localhost:nuxref): foobar
331 Please specify the password.
Password:
230 Login successful.
Remote system type is UNIX.
Using binary mode to transfer files.
ftp> ls
227 Entering Passive Mode (127,0,0,1,250,83).
150 Here comes the directory listing.
226 Directory send OK.
FileZilla FTPS Configuration
FileZilla FTPS Configuration

If you plan on using FileZilla as your solution, You need to configure it to connect as the FTP protocol with the Encryption set to Requires explicit FTP over TLS similar to the screen shot I provided.

You may or may not have to accept your certificate afterwards that we created earlier in this blog.

FileZilla On-Going FTPS Bug

The FileZilla Client is a pretty sweet application for those who like to work with a GUI instead of a command line. Those who choose to test their configuration with this should just know that there is an outstanding bug with FileZilla and the FTPS protocol. Hence, if you’re using Filezilla to to test your new VSFTPD server and it’s not working, it might not be your configuration at the end of the day. The versions seem to be hit and miss of which cause the bug to surface; reports of v3.5.2 working and v3.5.3 not. That all said, I’m using v3.7.3 and am not having a problem.

Here is the ticket #7873 that identifies the problem. One thing that is mentioned is that an earlier version of FileZilla works perfectly fine (specifically v3.5.2). But I’ve also had no problem with the current version (at the time was v3.7.3). I guess my main point is… don’t panic if you see this error; it’s not necessarily anything you’ve configured incorrectly. If you followed this blog then you shouldn’t have any issue at all.

Credit

I may not blog often; but I want to re-assure the stability and testing I put into everything I intend share.

If you like what you see and wish to copy and paste this HOWTO, please reference back to this blog post at the very least; it’s really all that I ask of you.

Sources: