Changes

Last week, {{Admon/important|Warning|Your lab 4a must be complete before you configured and ran the '''Postfix''' application for our MTA (a.k.a. SMTP server) on our '''vm2''' and '''vm3''' machinescan start this lab.}}

In Lab 4a, you configured and ran the '''Postfix''' application for our MTA (a.k.a. SMTP server) on your '''vm2''' and '''vm3''' machines. That setup has some major drawbacks:

::Note that your username is your full email address(<em>firstname.lastnameyourid@myseneca.ca</em>) and not just <em>firstname.lastnameyourid</em>.

 == INVESTIGATION 2: SETTING UP SETUP A CENTRALIZED MESSAGE STORE ==

# Look at Issue the '''mail''' command to 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 came from '''root@yourdomain.orgops'''.

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

<ol><li value="4">Edit the '''/etc/postfix/main.cf''' file.</li><li>Scroll 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</source>'''Note:''' Even though your machine's name is ''vm3.yoursenecaid.orgops'', your postfix MTA will also receive emails addressed to the domain called: yoursenecaid.orgops</li></ol>

<ol><li value="65">Add an '''MX''' record to the forward lookup zone on vm1 '''host''' so that all incoming mail addressed to the domain is sent to your vm3.</li><li>Restart the service and use the '''dig''' command to confirm that it works.</li><li>Send an email from your '''vm2 ''' to '''root@yourdomain.org.ops'''</li><li>Confirm that it arrives on your '''vm3''' machine.</li></ol>

=== 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 ===

<ol><li value="5">Restart your postfix service.</li><li>While '''Perform the emails are still stored only on VM3, they will now be easier for other machines/services to access.</li></ol>following steps:'''

#The configuration file for the Dovecot service (which is not the same thing as dovecot-lda) is: '''/etc/dovecot/dovecot.conf''Record steps'. Modify the '''protocols''' option so that Dovecot will work with IMAP connections, no POP3 or LMTP.# Start the dovecot service, commandsand 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 firewall on vm3 to allow IMAP connections from your observations in INVESTIGATION 2 in your OPS335 lab loglocal network and try '''nc''' again. Once it works, 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-bookssl.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.

==INVESTIGATION 3: USING THUNDERBIRD (MUA) FOR VM2 and VM3 MACHINES = 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>

===Online Submission (Peter CallaghanAhad Mammadov's Classes only)===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.

::<span style="color:green;font-size:1.5em;">&#x2713;</span>Download the labcheck4b.bash checking bash shell script by issuing the command:<br><br>and run '''wget httphttps://matrixict.senecac.onsenecacollege.ca/~peterandrew.callaghan/filessmith/OPS335ops335/labcheck4b.bash'''<br><br>set execute permission and run the shell script on your '''c7host''' machine. ::*For '''Peter's classes''', follow his Online Submission instructions in Moodle.::*For '''Murray's classes''', run command (piping to the '''more''' command) and show output to instructor.