== OVERVIEW & PREPARATION==Last week{{Admon/important|Warning|Your lab 4a must be complete before you can start this lab.}} In Lab 4a, we you configured and ran the '''Postfix''' application for our MTA (MTA a.k.a. SMTP server) on our your '''vm2''' and '''vm3''' machines. This  That setup had a drawback, in that it has some major drawbacks::* It required an SMTP server ('''MTA''') to be configured on each machine. :* The Message Store ('''MS''') would also be unique to each machine: - what a user received on one server would not exist on any other.  In this lab we you will centralize some of this information, so that a user can send email from any machine in the network, and have incoming mail sent to a centralized messages store.

We You will begin by modifying the existing '''Postfix''' ('''MTA''') servers to make mail they send come from your domain, (instead of each machine). Then we you will add a record to your DNS server to allow mail to be sent to the domain itself, instead of the individual machines. Next we , you will add a Local Delivery Agent ('''LDA''') to your '''vm3''' by installing '''dovecot-lda''', configure it, and test it to make sure that is is working correctly.

Finally, we you will set up an '''IMAP''' server (called '''Dovecot) ''' on VM3your '''vm3''' machine, so you can read your email from an MUA such as ''Thunderbird'' or a ''Webmail'' (we application. You will set up a webmail application called '''Roundcube''' in a later lab).

=== Learning About the Services involved Involved in email delivery an Email Delivery ===

[http://wiki.dovecot.org/MailServerOverview Here's is an overview] of those terms (from the Dovecot wiki). It is worth viewing this link.

* A '''userUser Account'''. That's the person The individual who wants to send an emailor receive mail messages.* An '''MUA''' (email client). This is the application that the user individual uses to send an emailor receive mail messages. It can be a '''native application ''' or a '''web application'''. We'll set up You will learn how to setup and use both typesof these applications throughout the remainder of this course.* Two '''MTAsMTA'''servers. These are the servers responsible for getting your emails to the <u>destination</u> server.

* The '''LDA/MDA''' Server. This server will receive the email from the MTA, and will store it on disk in some format. '''MailDir''' and '''MBOX''' are the most popular mailbox formats.* '''IMAP/POP3''' server(s). When sending an email, you send it to the destination using your MTA, but you also want to save it in your '''"Sent"''' folder for yourself. This is accomplished by a separate connection to either your '''IMAP''' or '''POP3''' server.

* Note that a '''DNS''' Server. A DNS server is also involved - it is needed to retrieve the address of the email server responsible for email for a particular domain. This is done with '''MX ''' records.

=== Install Unlike the '''mailx''' (MUA) application you installed and used in Lab 4a, this lab will be using the '''Thunderbird Application ''' (MUA) application instead which is a graphical application that uses a '''centralized Message Store''' (MS) to retrieve and Setup a Reference Client ===read mail messages.

Eventually Although wewill be eventually setting up the Thunderbird application to perform all the mail operations discussed above, you need to learn to '''"walk before you can run"''re '. Eventually, you are going to set up all those mail services, but to begin with, we you will set up an email client to connect to a (hopefully) an already working server - which is the '''Seneca email server'''. This will be a good exercise with an Once we learn how to do this for our Seneca email clientaccount, then we can use it for our mail servers for our VM2 and VM3.

#When you see first launch the Thunderbird application, a configuration dialog box, configure it in a similar way (''using your own information'') should appear as shown in the diagram below:

<br>::[[Image:Seneca-student-thunderbird-email-setup.png|600px]]<br><ol><li value="3">Use the data in the table below to configure the Thunderbird settings dialog box for YOUR Seneca e-mail account:</li></ol>

{| class="wikitable" border="1" style="margin-left:40px;"! Setting !! '''Incoming: IMAP''' !! '''Outgoing:Notice that there are <u>unencrypted</u> options available to connect to your SMTP'''|-| '''Username'''|| yoursenecauserid@myseneca.ca || yoursenecauserid@myseneca.ca|-| '''servername''' || outlook.office365.com || outlook.office365.com|-| '''port''' || 993 || 587|-| '''security''' || SSL/IMAP servers but those are rarely used these days TLS || STARTTLS|- the potential for abuse is too great| '''References''' | colspan="2" | [1] [https://employees.senecacollege. On a free wifi network, the operator would be able to not only read your email, but also obtain your password without any passwordca/spaces/77/encryption cracking tools. In fact, even on a private wired network, it is not uncommon for an employer to use a packet sniffer utility to monitor all the traffic going over their network (Packet Sniffing applications were actually found to be legally acceptable practices if used by the management of organizations).-services/wiki/view/2394/other-email-clients ITS - Configuring other Email Clients]|}

::The specific security settings depend on how Note that your servers were configured. '''The settings for the seneca servers are [https://inside.senecacollegeusername is your full email address(<em>yourid@myseneca.ca</itsem>) and not just <em>yourid</services/email/email_clients/imap.html published here]'''em>.

{{Admon/important |Unencrypted Options|Notice that there are <u>unencrypted</u> options available to connect to your SMTP/IMAP servers but those are rarely used these days - the potential for abuse is too great. On a free wifi network, the operator would be able to not only read your email, but also obtain your password without any password/encryption cracking tools. In fact, even on a private wired network, it is not uncommon for an employer to use a packet sniffer utility to monitor all the traffic going over their network (Packet Sniffing applications were actually found to be legally acceptable practice if used by the management of organizations)}}<br><ol><li value="3">After you create your '''Thunderbird''' account, you should be able to read your existing email and send new email within the Thunderbird application.</li><li>Take time to view your ''Account Settings'' and ''Preferences'' to get a feel for what settings exist. For example:<ul><li>How often will Thunderbird check for new messages?</li><li>Will the messages you write be in HTML or plain text?</li><li>How do you change your SMTP server settings? Why are they in a different section?</li></ul></li><li>The main objective of this section was to learn how to setup your Thunderbird application to read your Seneca email, so in the next section you can use the exact type of setup for your own email server.</li></ol>

== '''Record steps, commands, and your observations in INVESTIGATION 1: SETTING UP MTA FOR RECEIVING EMAIL ==in your OPS335 lab log-book'''

=== Specifying Which Domains are Used to Send Mail Messages=INVESTIGATION 2: SETUP A CENTRALIZED MESSAGE STORE ==

As of last lab, both of your email servers are sending mail addressed from users of the machines themselves. This would be confusing for the receiver who might get emails from the same user @vm1, vm2, and vm3. Which would they respond === Setup Your MTA to? To avoid this, we can make all servers make the sent mail appear to come from a common location (usually the domain), and make incoming email sent to that address accessible from machines inside our network.Use Correct Domain===

Look at the In Lab 4a, both of your email servers were sending mail messages you sent between your addressed from users of the actual machines themselves. This would be confusing for the receiver who might get emails from the same user @vm1, vm2 , and vm3 in lab 4a. Notice Which would they respond to? To avoid this problem from occurring, we can make all servers make the sent mail appear to come from a central location (usually the '''domain'''), and make incoming email sent to that each is addressed address to be accessible from root on whichever machine sent itmachines within our network.

On both machines, edit /etc/postfix/main.cf and change the '''myorigin''' parameter from ''Perform the following steps:'$myhostname''' to '''$mydomain'''. Restart postfix and send emails between the machines again. The sender address should now read root@yourdomain.org.

=== Specifying Which Domains are Used # Issue the '''mail''' command to Deliver view the email messages you sent between your '''vm2''' and '''vm3''' in your lab 4a. Notice that each is addressed from root on whichever machine sent it.# On both machines (vm2 and vm3), edit the '''/etc/postfix/main.cf''' file to change the '''myorigin''' parameter from '''$myhostname''' to '''$mydomain'''. Restart the '''postfix''' service.# Now, send emails messages (via the '''mail''' command) between both of your vm2 and vm3 machines, and view the mail messages by issuing '''mail''' in each vm. The sender address should now read that the "Received" Mail Messages===received mail messages came from '''root@yourdomain.ops'''.

Perform ::The next step is to configure what addresses that the server will receive email for. This is done using postfix by setting the following steps on vm3:'''mydestination''' parameter (configuration variable) to include '''$mydomain''' (this is assuming you've set up '''mydomain''', '''myorigin''' , and '''inet_interfaces''' properly).

<preol><li value="4">Edit the '''/etc/postfix/main.cf''' file for '''vm3 ONLY''', scroll down to the line containing: '''mydestination''' and change line to the text shown below:<br><source>mydestination = $mydomain, $myhostname, localhost.$mydomain, localhost</presource>'''Note:''' Even though your machine's name is ''vm3.yoursenecaid.ops'', your postfix MTA will also receive emails addressed to the domain called: yoursenecaid.ops</li></ol><br>::In order for this to work, we need to add a DNS record that will point mail sent to the domain towards one of the SMTP servers configured to accept it.

:<ol><li value="5">Add an '''Note:MX''' Even though your machinerecord to the forward lookup zone on '''host's name is ''so that all incoming mail addressed to the domain is sent to your vm3.yoursenecaid</li><li>Restart the service and use the '''dig''' command to confirm that it works.org</li><li>Send an email from your '''vm2''', your postfix MTA will also receive emails addressed to the domain called: yoursenecaid'''root@yourdomain.orgops'''</li><li>Confirm that it arrives on your '''vm3''' machine</li></ol>

In order for this to work, we need to add a DNS record that will point mail sent to the domain towards one of the SMTP servers configured to accept it. Add an MX record to the forward lookup zone on vm1 so that all incoming mail addressed to the domain is sent to your vm3. Restart the service and use dig to confirm that it works.  Send an email from your vm2 to root@yourdomain.org. Confirm that it arrives on vm3. === Relaying Relay Email Through Another Server===

*First, we must direct vm2 to relay mail through vm3, by editing /etc/postfix/main.cf again'''Perform the following steps:'''

# Move to your vm2 machine.# Direct your '''vm2''' MTA to relay mail through vm3, by making the following editing change for the '''/etc/postfix/main.cf''' file:<br><presource>relayhost = vm3.<yourdomain>.orgops</presource># Restart the '''postfix''' service.# Next, you must instruct your '''vm3''' machine to allow your vm2 machine to pass email through it by making the following editing change to the '''/etc/postfix/main.cf''' file:<br><source>mynetworks = 192.168.X.0/24</source>NOTE: Substitute in your '''own network''' for X<br><br># Restart the '''postfix''' service.

*Remember All mail is now being delivered to restart postfix once you a centralized location (and also appears to be coming from that same location), but a user would still have done so.*Next, we must tell vm3 to allow vm2 access that server to pass email through retrieve it:<pre>mynetworks = 192.168.X.0/24</pre>*Substitute in your own network for X, and remember to restart postfix.

All mail is now being delivered to a centralized location === Install and Configure the Local Delivery Agent (and also appears to be coming from that same locationLDA/MDA), but a user would still have to access that server to retrieve it.===

=== Installing Postfix is capable of performing the function of an LDA, but its LDA capabilities are limited, thus postfix is generally not used for that purpose. Currently, the most popular LDA is ''LMTP'', but we will be installing, configuring, and Configuring using an LDA called '''Dovecot''' since it is also popular and we will setting up Dovecot as an '''IMAP''' server later in this lab. Using both Postfix and Dovecot will actually increase the Local Delivery Agent (LDA) ===performance of our IMAP server.

Postfix is capable of performing the function of an LDA, but its LDA capabilities are limited, thus postfix is generally not used for that purpose. Currently, the most popular LDA is ''LMTP'', but we will be installing, configuring, and using an LDA called '''Dovecot''' since it is also popular and we will later be setting up Dovecot as an Perform the following steps:'''IMAP''' server. Using both Postfix and Dovecot will actually increase the performance of our IMAP server.

#Move to your '''Perform vm3''' machine.#Dovecot is not installed when you installed your Virtual machines in previous labs.<br>Install the Dovecot application by issuing the following steps on vm3command:<br><source>yum install dovecot</source>#Edit your '''/etc/postfix/main.cf'''file and scroll down to (or search for) '''mailbox_command'''. Add the following line:<br><source>mailbox_command = /usr/libexec/dovecot/dovecot-lda -f "$SENDER" -a "$RECIPIENT"</source>

#Dovecot is ::NOTE: Do <u>'''not installed '''</u> replace any variables, those are set automatically by Postfix when it runs the LDA. If you installed your Virtual machines are interested in previous labs.#Install learning more about the Dovecot application by issuing the following command, you can read about dovecot-lda [http://wiki.dovecot.org/LDA/Postfix here] and [http://wiki.dovecot.org/LDA here].<br>yum install dovecot#Edit your <ol><li value="4">Finally, edit the '''/etc/postfixdovecot/conf.d/main10-mail.cf file and scroll down to (or search for) conf'''mailbox_command'''. Add file and indicate where you want your mail delivered by including the following line:<source>mail_location = maildir:~/Maildir</source></li><li>Restart your postfix service.</li><li>While the emails are still stored only on VM3, they will now be easier for other machines/services to access.</li><li>Due to permissions on the directories where mail will now be stored, root will no longer receive mail. Check the logs for an indication as to why.</li></ol>

<pre>mailbox_command = /usr/libexec/dovecot/dovecot'''Record steps, commands, and your observations in INVESTIGATION 2 in your OPS335 lab log-lda -f "$SENDER" -a "$RECIPIENT"</pre>book'''

==INVESTIGATION 3:NOTE: Do <u>'''not'''</u> replace any variables, those are set automatically by Postfix when it runs the LDA. If you are interested in learning more about the Dovecot application, you can read about dovecot-lda [http://wiki.dovecot.org/LDA/Postfix here] USING THUNDERBIRD (MUA) FOR VM2 and [http://wiki.dovecot.org/LDA here].VM3 MACHINES ==

<ol><li value="4">Finally, edit the '''/etc/dovecot/conf.d/10-mail.conf''' file and indicated where you want your mail delivered by including the following line</li></ol>== Accessing Received Mail Messages on VM3 VIA IMAP ===

While #The configuration file for the Dovecot service (which is not the same thing as dovecot-lda) is: '''/etc/dovecot/dovecot.conf'''. Modify the '''protocols''' option so that Dovecot will work with IMAP connections, no POP3 or LMTP.# Start the dovecot service, and ensure it will always start automatically when the machine boots.# Use the '''ss''' command to confirm the service is listening, and use '''nc''' on the '''host''' to confirm you can connect to it.# You'll probably fail, so using the information gathered from '''ss''', modify the emails are still stored only firewall on VM3vm3 to allow IMAP connections from your local network and try '''nc''' again. Once it works, they do not forget to save this change so it will still be there the next time you reboot.#If you can connect - it's now time to do something wrong, that is allow connections to our IMAP server over an unencrypted connection.# Edit the '''/etc/dovecot/conf.d/10-auth.conf''' file and set '''disable_plaintext_auth''' to '''no'''.# Then edit the '''/etc/dovecot/conf.d/10-ssl.conf''' file and set '''ssl''' to '''yes'''.<br><br>'''Note:''' This combination of parameters will allow your username and password to be easier sent over the internet in plain text, for other machines/services anyone interested to accesslook at. In a later lab we'll set up secure SMTP and IMAP connections, for now this is all we have time for.<br><br># Restart dovecot so the changes take effect.

==INVESTIGATION 2: SETUP THUNDERBIRD MAIL USER AGENT (MUA) FOR YOUR VIRTUAL NETWORK (vm2, vm3) = Connecting to IMAP Servers Using Thunderbird===

#On your '''host ''' machine, return to the Mail Account Setup dialog box (eg. near top of lab).# Set up the a '''new email account'''. You will be using account settings to connect to your '''vm2''' for '''SMTP''' and '''vm3''' for '''IMAP'''. Use <u>no</u> encryption, and use normal password authentication for IMAP (we don't have an IMAP server running yet, but that's ok). Refer to the diagram below for reference:

::<ol><li value="3">Try to connect to your IMAP server with Thunderbird by clicking on your '''NOTE:Inbox''' .</li><li>If nothing happens, then check the Thunderbird won't let Activity Manager for any errors. If the connection is successful, you proceed with should see the "Done" button because you will fail to connect to IMAP. '''Trash''' box <olu>appear<li value="3"/u> Use the "Advanced config" button to bypass that checkbelow Inbox.</li><li>Use the Thunderbird application to send an email to your myseneca address. If you've done everything right, it will send the message successfully, but it will fail to save it in the Sent folder since that's done with IMAP and you don't have an IMAP server yet.</li><li>Verify that your message has been sent. Check your myseneca email and look at '''/var/log/maillog''' on vm2 (your email server).</li></ol>

#Use the '''ss''' and '''nc''' commands (like you did in lab 4a) to confirm your service is listening on the correct ports/interfaces. You will probably have to open the appropriate firewall port on '''vm3''' to allow incoming '''SMTP''' connections.<br><br>'''Note:''' You should be able to send email to any regular user <u>on</u> '''vm3''' using the email address '''yourusername@yoursenecaid.orgops''' using the Thunderbird application on your host machine (which is configured to use the account on your vm2).<br><br>

<ol><li value="2">Create a new account on your '''vm3''' machine using only your <u>first</u> name. We will use this account as a one-time "test" if the mail message has been received on your VM3 machine (from your VM2 machine).<br><br>'''Note:''' It is <u>'''important'''</u> that you '''<u>don't</u>''' create this same account name on your vm2 machine, since you want to easily identify the difference between the sending and receiving SMTP servers.<br/><br/></li></ol>

<ol><li value="3">We still haven't set up IMAP (for reading email) but we can test that the message is being delivered. Use the new account in Thunderbird to send an email to '''firstname@yoursenecaid.orgops''' and then check the contents of '''/home/firstname/Maildir/new/''' on your '''vm3''' machine. There should be a file there with the contents of your email.</li><li>If there is no file, then check the log file '''/var/log/maillog''' to see what went wrong.</li><li>If you can see a file in the '''/home/firstname/Maildir/new/''' directory, then review the procedures on how you got the email server working (since you have performed many steps and set up many services).</li><li>Refer to the diagram at the top of this lab. Which services have you currently set up? Record your findings in your lab Logbook.</li></ol>

{{Admon/important |Encountering error messages when sending email|If you cannot properly receive sent e-mail messages, check the '''/var/log/syslog''' file for errors.<br><br> If you locate an error message in that file such as: '''Fatal: Error reading configuration: Invalid settings...''', then add the following <u>parameter</u> in '''/etc/dovecot/dovecot.conf''':<br/>'''postmaster_address at <nowiki>=</nowiki> DOMAIN''' (where DOMAIN is actually <u>your</u> domain).<br/><br/>After you have saved those changes, then '''restart''' your dovecot service. This problem can also be resolved by properly setting the hostname of your machine to include the domain.}}

=== Viewing Received Mail Message {{Admon/important |Backup your VMs!|You MUST perform a '''full backup''' of ALL of your VMs whenever you complete your '''OPS335 labs''' or when working on VM3 VIA IMAP (Using Thunderbird) ===your '''OPS335 assignments'''. You should be using the dump or rsync command, and you should use the Bash shell script that you were adviced to create in order to backup all of your VMs.}}

Finally, we will set up the IMAP server so we can read email. The current way we have configured our mail server on our VM3 machine should allow all the email for anyaccount@yoursenecaid.org should be delivered to our '''vm3''' machine. We will set up Dovecot with IMAP to get easy access to that email. '''Perform the following steps:''' #The configuration file for the Dovecot service (which is not the same thing as dovecot-lda) is: '''/etc/dovecot/dovecot.conf'''. Modify the '''protocols''' option so that Dovecot will work with IMAP connections, no POP3 or LMTP.# Start the dovecot service, and ensure it will always start automatically when the machine boots.# Use the '''ss''' command to confirm the service is listening, and use nc on the host to confirm you can connect to it.# Using the information gathered from ss, modify the firewall on vm3 to allow IMAP connections from your local network. Remember to add this to your firewall_restore script.#If you can connect - it's now time to do something wrong, that is connect to our IMAP server using Thunderbird over an unencrypted connection.# Edit the '''/etc/dovecot/conf.d/10-auth.conf''' file and set '''disable_plaintext_auth''' to '''no'''.# Then edit the '''/etc/dovecot/conf.d/10-ssl.conf''' file and set '''ssl''' to '''yes'''.<br><br>'''Note:''' This combination of parameters will allow your username and password to be sent over the internet in plain text, for anyone interested to look at. In a later lab we'll set up secure SMTP and IMAP connections, for now this is all we have time for.<br><br># Restart dovecot so the changes take effect.#Try to connect to your IMAP server with Thunderbird by clicking on your '''Inbox'''.#If nothing happens, then check the Thunderbird Activity Manager for any errors. If the connection is successful, you should see the '''Trash''' box <u>appear</u> below Inbox.# Finally, send an email message from '''yoursenecaid@yoursenecaid.org''' to '''yoursenecaid@yoursenecaid.org''' using the Thunderbird application. The mail message should be sent without errors, and you should notice a '''Sent''' folder appear in the list. If all worked well, you should see your message arrive in the '''Inbox''' and you know that your configuration works correctly. '''Record steps, commands, and your observations in INVESTIGATION 2 3 in your OPS335 lab log-book'''

Follow the instructions for lab 4b on moodleblackboard.<!--===Andrew's sections===

===In Class Submission===You may choose to:Students should be prepared with * Submit screenshots of your work on Blackboard, in which case you don'''all required commands (system information) displayed in a terminal (or multiple terminals) prior t need to come to the lab.* Or come to calling the instructor for signoff''lab, show me your work, and talk to me about it. I want to hear what you've learned and answer any questions you have.

You'''Arrange evidence (command output) for each ll get the same grade regardless of these items on how you choose to submit your screen, then ask your instructor to review them and sign off on the lab's completion:'''work.