View on GitHub

Ubuntu VSFTPD

Written by Carlos Leon

Debian Email Box

Contact

Table

  1. Prerequisites
  2. Setup Debian VM
  3. Install Postfix
  4. Install Dovecot
  5. Install Webmail
  6. Testing

Prerequisites

  1. Have your virtual environment configured
  2. Have the ISP gateway running.
  3. Have pfSense running.

Summary

An Email system is comprised of a couple of parts. First is the Mail Transport Agent or MTA for short. The MTA gets and send messages over SMTP - Postfix will be our MTA. Then the MTA passes its data off to the Mail Delivery Agent or MDA for short. The MDA, normally, uses IMAP or POP3 protocol to save the emails in an users inbox. We will be using Dovecot as our MDA with IMAP protocol. The specific differences between IMAP and POP3 aren’t necessary to know, but in general IMAP is for reading mail on the server and leaving it there, and POP3 is for reading mail on a local machine copied from the server. In our case, IMAP is simpler to setup. Lastly, is the Mail User Agent or MUA. This can refer to the user in general, or specifically to the way the user accesses their inbox. We will be using webmail as our MUA.

TL;DR This is the setup guide for the Debian Email box. We will be using a Postfix as our MTA, dovecot as MDA, and webmail as our MUA.

diagram2

Setup Debian VM

  1. First, go get the Debian server from ISO here. Then, open up VirtualBox, create a new Linux Debian (64-bit) VM, the default setting will do. Then alter the network settings to use Host-only adapter instead of NAT. Insert the downloaded ISO into the virtual optical drive and boot.

  2. Select options as follows in the installation (pretty much a standard setup)
    1. Choose Graphical install
    2. English
    3. United States
    4. American English
    5. “debian”
    6. “debian-email.com”
    7. {super secret password}
    8. {some user}
    9. {some user password}
    10. Eastern
    11. Guided - sue entire disk
    12. All files in one partition
    13. Finish partitioning
    14. Yes - write to file
    15. No
    16. United States
    17. ftp.us.debian.org
    18. No - no popularity contest
    19. For software selection pick only: standard system utilities
    20. Yes - to grub
    21. /dev/sda - should be the only disk
  3. Now you should see a terminal login prompt. Login. login

Install Postfix

Here we will install Postfix.

  1. Preperations

    First become superuser and fetch updates

     su
 # Enter the {super secret password}
 apt-get update
 apt-get upgrade

    Now install some packages that will be useful later

     apt-get install -y net-tools wget curl

    Now open up /etc/host.conf file with vi configure it so it looks like so. What this does is essentially that whenever the server tries to go to any external resource, i.e. the Internet, it will first look at the host file.

     order hosts, bind
 multi on

    Now we add our ip and domain name ‘debian-email.com’ to the host file so it will internally resolve. Essentially, whenever out server tries to go to debian-email.com it will look at the host file, see theres a rule telling it to point to a specific ip, and go to that IP. And that IP will be the servers own IP.

    First, get the IP by running ifconfig .

     $ ifconfig
 eth0      Link encap:Ethernet  HWaddr fc:aa:14:29:7a:11
       inet addr:10.0.2.15 Bcast:192.168.0.255  Mask:255.255.255.0
       inet6 addr: ::b9bf:5d35:cc8c:ff30/64 Scope:Global
       inet6 addr: ::d498:a9c5:e386:65a9/128 Scope:Global
       inet6 addr: fe80::b9bf:5d35:cc8c:ff30/64 Scope:Global
       UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
       RX packets:0 errors:0 dropped:0 overruns:0 frame:0
       TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
       collisions:0
       RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

    Yours will look similar, now look for inet, use your IP instead of 10.0.2.15.

    Now actually set the rules.

     hostnamectl set-hostname mail.debian-email.com
 echo "10.0.2.15" debian-email.com mail.debian-email.com >> /etc/hosts

    Now reboot: reboot . Then become superuser again

2. Install postfix

``` bash
apt-get install -y postfix
# A graphical-esc inerface pops up
# For Mail Configuration: Internet Site
# Our mail name will be: "debian-email.com"
``` 3. No we need to make some adjustments to the postfix configuration

Go to `/etc/postfix` and edit the `main.cf` file with `vi`
```bash
# Find the line that reads myhostname= and change to
myhostname=mail.debian-email.com

# Add the following line
mydomain=debian-email.com  # Allows us to use use user@debian-email.com
home_mailbox = Maildir/    # Tels Dovecot where to dump our mail
smtpd_sasl_type = dovecot  # Whaat to do for authentication - Dovecot
smtpd_sasl_path = private/auth  # Config file for auth
smtpd_sasl_auth_enable = yes  # Use authentication
smtpd_sasl_security_options = noanonymous  # Dissalow anonymous login
smtpd_sasl_local_domain = $myhostname  # use debian-email.com for domain

# permit_auth_destination means skip auth if we are the destination
# permit_mynetworks means allow networks specified in my_networks
# permit_sasl_authenticated means allow if sasl auth (what we are using)
# reject, if no other restriction allows it, reject everything
smtpd_recipient_restrictions = permit_mynetworks,permit_auth_destination,permit_sasl_authenticated,reject
```

Run `postconf -n` and check there where no misspellings

Then restart postfix service
```bash
systemctl restart postfix
```

  1. verify that postfix is listening on port 25

    Run netstat -ant . We are looking for two rows that reads

      tcp    0    0   0.0.0.0:25    0.0.0.0:*    LISTEN
  tcp6   0    0   :::25         :::*         LISTEN


Install Dovecot

Here we will install Dovecot.

  1. install dovecot core and dovecot IMAP so that mail can be retrieved using the IMAP protocol. 
     apt-get install -y dovecot-core dovecot-imapd

  2. Go to /etc/dovecot we need to make some small configuration changes

    Edit the dovecot.conf file with vi

     # Near the bottom of the file, find this line and uncomment it
 listen =*, ::

    Next edit the ./conf.d/10-auth.conf file with vi.

     #  set as follow
 disable_plaintext_auth = no
 auth_mechanisms = plain login

    Next edit the ./conf.d/10-mail.conf file with vi.

     #  set as follow
 mail_location = maildir:~/Maildir

    Next edit the ./conf.d/10-master.conf file with vi.

     # Look for the commented section Postfix smpt-auth
 # uncomment what is there and add so it looks like... 
 # Postfix smtp-auth
     unix_listener /var/spool/postfix/private/auth {
     mode = 0666
     user = postfix
     group = postfix
 }

    Finally restart dovecot

        systemctl restart dovecot
  3. Verify that Dovecot is listening on the right ports by running netstat - ant again 
         tcp    0    0   0.0.0.0:143    0.0.0.0:*    LISTEN
     tcp6   0    0   :::143         :::*         LISTEN
  4. Lastly, add a Maildir for every user 
     echo "export MAIL=$HOME/Maildir" >> /etc/profile
 mkdir -p /etc/skel/Maildir/{cur,new,tmp}


Install Webmail

This will provide a GUI users can use to see their mail

  1. First we install the dependencies 
     apt-get install -y php7.0 libapache2-mod-php7.0 php7.0-curl php7.0-xml

  2. Install webmail

    First go to /var/www/html and delete the index.html file with rm Next download the webmail installer

     curl -sL https://repository.rainloop.net/installer.php | php
 # Then you should see this after a bit...

    webmail-install

  3. Access this box via the web

    Assuming DNS has been setup to redirect debian-email.com to its IP, if not add the redirect your hosts file on linux/windows, or just use the IP. In any case go to http://debian-email.com/?admin or http://10.0.2.5/?admin

    When you get there you will see a login page, login with…

     User: admin
 Password: 12345

    Go to Domains > add

     Imap
 ------
 Server: 127.0.0.1
 Port: 143
 Secure: None
 Use short Login: yes
    
 SMTP
 ------
 Server: 127.0.0.1
 Port: 25
 Secure: None
 Use short Login: yes
 Use authentication: yes

    front-end


Testing

Lets make sure everything works

  1. Users

    Every user on the box should have a Maildir folder To test this, add a new user. The -m means create a folder in home for them.

     useradd -m jeff
 passwd jeff
 # We should see a Maildir folder exists
 ls /home/jeff
 # We should see a cur, new and temp folder exists
 ls /home/jeff/Maildir

  2. SMTP

    If everything went right, SMTP should be working. To test that out install mailutils

     apt-get install -y mailutils
 # Now execute these commands
 echo "TEST EMAIL" | mail -s "testmail" jeff
 mailq
 mail

    Now cat out the contents of jeff user Maildir/new folder content

     # use tab autocomplete here since the file name will be long
 cat /home/jeff/Maildir/new/[tab]
 # Expect something like
    
 Return-path: <root@mail.debian-email.com>
 X-Original-To: jeff@mail.debian-email.com
 Delivered-To: jeff@mail.debian-email.com
 Received: by mail.debian-email.com (Postfix, from userid 0)
         id A981141DF1; Thu,   1 Feb 2018 20:50:14 -0500 (EST)
 Subject: testmail
 To: <jeff@mail.debian-email.com>
 X-Mailer: mail (GNU Mailutils 3.1.1)
 Message-Id: <214324242342342342.A981141DF1@mail.debian-email.com>
 Date: Thu,   1 Feb 2018 20:50:14 -0500 (EST)
 From: root@mail.debian-email.com (root)
    
 TEST EMAIL

  3. Webmail

    Use the user we created and log in to webmail

     login
 -----
 jeff@debian-email.com
 password

    Confirm that you can indeed login. From here you should be able to see you inbox with has the mail we sent from earlier.

Photo by Lauren Mancke / Unsplash