OPS335 Email Lab

Basic Mail (Postfix) Setup

This lab will show you how to set up a Postfix email server using a Fedora 16 installed PC.

• You will need at least two systems to do this lab. The first could be Fedora on your removable hard drive while the second could be a virtual machine.

Prerequistites
Your hard drive should have Fedora 16, 64 bit Live edition already installed.
Both host and guest should have all software updated.
Ensure the clocks on both machines are set to the correct date and time.

Testing your network

• Start Firefox on your host and authenticate yourself on Senenet with your LEARN account.
• Ensure you can surf the web on your host machine.
• Ensure you can access the web on your VM (you can use wget for that). NOTE: you should not have to authenticate yourself on the guest.

Testing email to the outside world using mailx and sendmail

• Sendmail is installed and running by default on Fedora 16 so there is no need to install it.
• Install mailx on both the host and the guest.

yum install mailx

• Test email from the host by sending an email to your LEARN account.

mail -s "PART C3" xxxxxx@learn.senecac.on.ca 

Note: xxxxxx is your LEARN ID.
Note: after you type in your letter, enter a period in the first column on the last line and hit the ENTER key.

• Check your LEARN email to see if you got the email. If you did make a note of the return address.
• Test email from the host by sending an email to your LEARN account.

mail -s "PART C4" -r hacker@evil.com xxxxxx@learn.senecac.on.ca

Note: xxxxxx is your LEARN ID.
Note: after you type in your letter, enter a period in the first column on the last line and hit the ENTER key.

• Check your LEARN email to see if you got the email. If you did make a note of the return address.
• Repeat these steps on the guest machine.

Install and configure Postfix

• On both machines do the following:
  • Stop sendmail.

systemctl stop sendmail.service

• Install Postfix

yum install postfix

• Edit the Postfix configuration file, /etc/postfix/main.cf, and change the following lines ( be sure that there are no other instances of that line as well, comment as needed):

 mydomain = <learnid>.org
 myorigin = $mydomain
 mynetworks = 127.0.0.0/8, 192.168.X.0/24
 relay_domains =
 inet_interfaces=all

• Start Postfix on both machines:

systemctl start postfix.service

Testing email using IP Addresses

• If you have problems with the following you may have to set SELinux to permissive mode and/or adjust your firewall to allow traffic to/from port 25.
• Try sending an email from vm01 to your host.

mail -s "PART E2" yyyyyy@[192.168.X.1]

Note: yyyyyy is your learn ID
Note: the square brackets around the host IP address

• Try sending an email from your host to vm01.

mail -s "PART E3" zzzzzz@[192.168.X.2] 

Note: zzzzzz is your learn ID

Test email using host names

For this part make sure that your f16 machine has the following entry added in /etc/postfix/main.cf to the mydestination line: f16.$mydomain

Now try sending mail to yourself on both machines. For example, as <learnid> on f16, use the command:

$ mail <learnid>@f16

the machine will prompt for a subject: enter "testing" without the quotes.

• Now enter the body of your letter. When you're done, enter a period (.) in column 1 on the last line of your letter. This will signal end-of-file and your letter will be mailed. You should end up back at the $ prompt. If you mess up use CTRL-C to cancel the email, DO NOT USE CTRL-Z.

• Use the mailq command (you will need to be root) to view the mail queue.

Use the mail command to check if you have mail.

Test your configuration and view your logs

• Restart your postfix servers on both machines.
• Check your /var/log/messages file to see that your postfix servers started without error.
• Send some emails from both guest and host to each other and to the outside world.
• Check your /var/log/maillog file to see that your email messages were sent correctly.

Learning the mail command

• Read the mail manual page and learn how it works.

Completing the Lab

1. Include a copy of your main.cf file on vm01 (your guest) with this lab - but delete all commented and blank lines first - like this. [cat /etc/postfix/main.cf | grep -v ^# | awk 'NF > 0 {print $0}']
2. What is the output of the iptables-save command on both your host and guest machines?
3. What firewall rule or rules, if any, did you have to enter on the guest and/or host so that email to/from each other would work?
4. What is the meaning of the square brackets surrounding the IP address in the examples?
5. What were the results of sending email between the host and the vm? Show log segments to verify your answers.