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[[Image:email-setup-simple.png]]
Although, you will not be able to receive mail messages from outside sources (such as your Seneca email account), this lab acts as a starting point in order to run a basic email server. You are NOT required you to go into tremendous depth (just the minimum requirements). For example, we will not go over every aspect of the Postfix MTA service, but you should know what it represents and what is its main purpose, as opposed to the following: [https://en.wikipedia.org/wiki/Postfix_%28software%29#Architecture complex diagram 1] , [https://www.credativ.de/blog/postfix-architecture-overview complex diagram 2].
===Online References:===
We will be using a simple text-based '''Mail User Agent (MUA)''' called '''mailx''' in this lab to '''both send and receive''' mail messages within your '''vm2''' machine and to '''only send''' mail messages from your '''vm2''' machine to your Seneca e-mail account.
'''NOTE:''' Due to the simplicity of this mail server setup Because you're using private IP addresses and the lack of other no external DNS servers are pointing to your network, and the setup of Seneca College's mail server, you '''<u>cannot</u>''' send Seneca e-mail messages from outside your environment to your '''vm2''' machine.
=== Installing the Mail User Agent (MUA)===
#Make certain you are in your '''vm2''' machine.
#Issue the following command to install Install the '''mailx''' application (MUA):<br>'''using yum install mailx'''<br><br>
:'''NOTE:''' You can refer to the link below to acquaint yourself on how to send e-mail messages using '''mailx''' application:<br> [http://www.simplehelp.net/2008/12/01/how-to-send-email-from-the-linux-command-line/ Mail Send Command Examples]
===Sending a Mail Message from your vm2 Machine to your Seneca Email Account===
{{Admon/important|Note|These instructions no longer work reliably. You can still send email to your own email server, and look at the server logs to see that it did really get sent. But it probably won't be accepted for one of a multitude of good reasons.}}
We will now test to see if your MTA for your vm2 machine is correctly running by sending email messages from your vm2 machine to your Seneca e-mail account.
#Check your Seneca email account (Inbox / Junk Email Folder) to see if you got the email (note that it may take a <u>few minutes to arrive</u>, so you may also wish to try an alternate email account if you have one like gmail, etc). When you do receive that email, make a note of the return address.
#If you did not receive the mail, check the mail logs on your vm2 machine to determine any errors messages that would indicate a mail server setup problem.
#Once you have succeeded in sending the first email, send a second email to the same destination using the following command:<br>'''mail -r "someone@hacker.com (Canadian Revenue Agency)" -s "Lab4a - test2" <Your Seneca email address>
#Check your email to see if you got the email. If you did, make a note of the return address. How would you think that including the '''-r''' option could be used by penetration hackers to gain access to a computer system? What sort of steps do you think should be taken to help prevent this type of attack from happening?
Follow the instructions for lab 4a on blackboard.
===In Class Submission (Murray SaulAndrew's Classes only)sections=== You may choose to:* Submit screenshots of your work on Blackboard, in which case you don't need to come to the lab.* Or come to the 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'll get the same grade regardless of how you choose to submit your work.
::<span style="color:green;font-size:1.5em;">✓</span>Arrange proof that you can send e-mail from your '''vm2''' machine to your '''Seneca College e-mail account''', and than you can '''send and receive e-mail messages between on your vm2 and vm3 machines'''.
::<span style="color:green;font-size:1.5em;">✓</span>Download the labcheck4a.bash checking bash shell script by issuing the command:<br><br>and run '''wget httphttps://matrixict.senecac.onsenecacollege.ca/~peterandrew.callaghansmith/files/OPS335ops335/labcheck4a.bash'''<br><br>set execute permission and run the shell script on your '''host''' machine. ::*For '''Peter's classes''', follow his Online Submission instructions in Moodle.::*For '''Murray's classes''', run command (piping to the '''more''' command) on both VM2 and VM3 and show output to instructor.
::<span style="color:green;font-size:1.5em;">✓</span>Completed Lab4a log-book notes.
