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Explorer
Posts: 20
Registered: ‎06-26-2017

Is it require to disable the postfix service even after cloudera hadoop installation also

[ Edited ]

Hi Team,

 

Myself Balaji working as a cloudera hadoop admin.

 

During cloudera CM and CDH installtion we have disabled the postfix service, now cloudera cm and cdh running fine.

Now i want to enable the postfix to send notifications, can i goahead and enable it.

or

 

please let me know if there is any impact if i enable it.

 

Please suggest on this.

 

Thanks

Balaji Vemula

New Contributor
Posts: 3
Registered: ‎01-19-2018

Re: Is it require to disable the postfix service even after cloudera hadoop installation also

 

Step 1 — Installing Postfix
In this step, you'll learn how to install Postfix. The most efficient way to install Postfix and other programs needed for testing email is to install the mailutils package.

First, update the package database:

 

sudo apt-get update


Finally, install Postfix. Installing mailtuils will install Postfix as well as a few other programs needed for Postfix to function.

 

sudo apt install mailutils


Near the end of the installation process, you will be presented with a window that looks exactly like the one in the image below. The default option is Internet Site. That's the recommended option for this tutorial, so press TAB, then ENTER.

Select Internet Site from the menu, then press TAB to select <Ok>, then ENTER

After that, you'll get another window just like the one in the next image. The System mail name should be the same as the name you assigned to the server when you were creating it. If it shows a subdomain like subdomain.example.com, change it to just example.com. When you've finished, press TAB, then ENTER.

Enter your domain name, then press TAB to select <Ok>, ENTER

After installation has completed successfully, proceed to step two.


Step 2 — Configuring Postfix
In this step, you'll read how to configure Postfix to process requests to send emails only from the server on which it is running, that is, from localhost.

For that to happen, Postfix needs to be configured to listen only on the loopback interface, the virtual network interface that the server uses to communicate internally. To make the change, open the main Postfix configuration file using nano or your favorite text editor.

 

sudo nano /etc/postfix/main.cf


With the file open, scroll down until you see the following section.

/etc/postfix/main.cf
. . .
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
. . .
Change the line that reads inet_interfaces = all to inet_interfaces = loopback-only.

/etc/postfix/main.cf
. . .
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = loopback-only
. . .
Another directive you'll need to modify is mydestination, which is used to specify the list of domains that are delivered via the local_transport mail delivery transport. By default, the values are similar to these:

 

/etc/postfix/main.cf

. . .
mydestination = $myhostname, example.com, localhost.com, , localhost
. . .
The recommended defaults for that scenario are given in the code block below, so modify yours to match:

 

/etc/postfix/main.cf

. . .
mydestination = $myhostname, localhost.$mydomain, $mydomain
. . .

Save and close the file.

If you're hosting multiple domains on a single server, the other domains can also be passed to Postfix using the mydestination directive. However, to configure Postfix in a manner that scales and that does not present issues for such a setup involves additional configurations that are beyond the scope of this article.

Finally, restart Postfix.

 

sudo systemctl restart postfix



Step 3 — Testing the SMTP Server
In this step, you'll test whether Postfix can send emails to an external email account using the mailcommand, which is part of the mailutils package that was installed in Step 1.

To send a test email, type:

 

echo "This is the body of the email" | mail -s "This is the subject line" your_email_address


In performing your own test(s), you may use the body and subject line text as-is, or change them to your liking. However, in place of your_email_address, use a valid email address. The domain part can be gmail.com, fastmail.com, yahoo.com, or any other email service provider that you use.

Now check the email address where you sent the test message. You should see the message in your inbox. If not, check your spam folder.

Note that with this configuration, the address in the From field for the test emails you send will be sammy@example.com, where sammy is your Linux username and the domain part is the server's hostname. If you change your username, the From address will also change.


Step 4 — Forwarding System Mail
The last thing we want to set up is forwarding, so you'll get emails sent to root on the system at your personal, external email address.

To configure Postfix so that system-generated emails will be sent to your email address, you need to edit the /etc/aliases file.

 

sudo nano /etc/aliases


The full contents of the file on a default installation of Ubuntu 16.04 are as follows:

/etc/aliases
# See man 5 aliases for format
postmaster: root
With that setting, system generated emails are sent to the root user. What you want to do is edit it so that those emails are rerouted to your email address. To accomplish that, edit the file so that it reads:

 

/etc/aliases

# See man 5 aliases for format
postmaster: root
root: your_email_address
Replace your_email_address with your personal email address. When finished, save and close the file. For the change to take effect, run the following command:

 

sudo newaliases


You may now test that it works by sending an email to the root account using:

 

echo "This is the body of the email" | mail -s "This is the subject line" root


You should receive the email at your email address. If not, check your spam folder.

Explorer
Posts: 20
Registered: ‎06-26-2017

Re: Is it require to disable the postfix service even after cloudera hadoop installation also

Thank you so much for your reply, but my question is something different!

New Contributor
Posts: 1
Registered: ‎12-21-2018

Re: Is it require to disable the postfix service even after cloudera hadoop installation also

Enabling the default postfix configuration can fail if IPv6 is disabled, especially on RHEL 7.

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