Tag Archives: smtp

Linux Mail From the Command Line

Local Mail Using Postfix and Mail

Info Links, Linux, My Thoughts, Server, , , , , , ,

Mail on the command line. This was once a thing that was used much more often. When I was in college in the 1990’s it was one of the easiest ways to get mail when on campus and off. It was taught to technical and non-technical people alike as part of orientation and you were given written instructions right at registration time. Instructions came along with the email account that they made up for you using a student id number followed by @binghamton.edu. In fact, finally in the last year I was there they got rid of this cumbersome email and started allowing users to have email with their real names.

Getting to mail back then from the command line involved logging into your Unix account from one of the many terminals spread throughout the campus. Or using the  insecure but, OK at the time rlogin, remotely via dialup. Then you could either use mail or pine which was a bit more sophisticated as it was based off the pico editor, of which the popular nano editor is a derivative. It at least has somewhat of an interface that accepts up and down arrow movement and displays the shortcuts on the bottom. The standard mail program is a bit like vi, spartan but still useful.

Having access to mail locally on the command line is useful when you might be running CRON tasks or any other automated scripts that call other code as it allows you to get notified of when they have run and most importantly if they have had errors.

The other alternative is to set up ssmtp and have mail sent out of the local machine using SMTP from another established account. Of course you can also set up a full blown mail server but, that can be overkill if you are just monitoring what is happening on a few machines that you regularly log in to.

Setting up Local Mail

Below is a great Github post on how to set up local mail on a Linux Machine. I followed it and added a variation to get local mail running using the command line mail program.

It works great.  I really liked the instructions, very easy to set up. I was glad I found this as, I thought it might be tricky and with these instructions it was a few minutes on each machine.

Setup a Local Only SMTP Email Server (Linux, Unix, Mac)

 

My Additions

Server

For use with mail the program, it might not be necessary to have a local host.com in the host file. I have not tested this.

I followed the tutorial up to and including the step of restarting postfix.

Then I installed mail instead of Thunderbird.

On the server, which only has a CLI,  I wound up using mail instead of T-bird, installed via sudo apt-get install mailutils
It can be tested by sending a message to yourself by using…
mail -s “test” (your user name)@localhost

Hit enter when in the screen to bypass CC , type something and end by using Ctrl D.

Then enter the command

mail

…and you should see the email. Hit enter at the? prompt and the message is presented.

Enter q to quit.

Another test message can be sent to test if a message to any address gets sent to you. As long as the domain is local host it will work and catch it. Other domains will fall and send you an email from the system reporting the email as undeliverable.
It works great to get the CRON messages on the machine.
Just type mail and you get a CLI email list. mail basics are, q to quit, m to compose, enter and spacebar to move through messages. Entering question mark ?, brings up command help.

Desktop Install

One gotcha that caught me is that I already had T-bird installed and therefore it had a default SMTP server already. For me this required what I would call step 6A to add a local STMP server.
6A. In the pane above “Account Actions” scroll, using the bar to the bottom “Outgoing Server (SMTP)”.
Click Add
For description I wrote Local SMTP
Server Name: localhost
Port: 25
Username : (the user name)@localhost
Authentication Method: Password, transmitted insecurely
Connection Security: None

Then I went back into the account settings for the mail set up in step 6 and set the Outgoing Server (SMTP) to the Local SMTP

Host File Aliases

Also in /etc/hosts you can put in localhost.com as a alias and it works fine, like this…
127.0.0.1       localhost localhost.com

This is the way to put in aliases in a host file, for example you can have the machine name and then a shortcut to it if you have it set to a static IP. This way you can just type server to SSH to it and use that as a short name wherever you want to in scripts and etc.

192.168.1.10  Dell-Optiplex-620     server

127.0.0.1 localhost localhost.com

 

 

Additional utilities for a Linux Server

Server, , , , , ,

vsftp

Sometimes it is nice to have an ftp server, you might have Samba and ownCloud, but sometimes you really need ftp to do something. It is the right tool at the right time and I can’t imagine running a server without FTP installed.

sudo apt-get install vsftpd
Edit the configuration file

Back it up first then do an edit

sudo cp /etc/vsftpd.conf /etc/vsftpd.orig
sudo nano /etc/vsftpd.conf

uncomment local_enable = YES

uncomment write_enable = YES

In this manner you will be able to read and write to your home directory. With SSH and FTP you can do just about anything remotely to your server. You can ( put ) FTP a file up to your home and move it anywhere and in the opposite direction also ( get ).

For example I downloaded the zip file for the OwnCloud Music App on a Windows computer, then FTP’d it the Linux server into my home directory and moved and unzipped it in the proper directory using SSH. Zip/unzip is not loaded by default with the Ubuntu Server disc, to get it see below.

This is powerful and with that power comes danger. You don’t want anyone to be able to SSH and FTP in, so be careful when opening these ports. I get “hits” on port 22 for SSH a lot, I don’t even open port 21 for FTP outside of my LAN. When I mean hits, I mean I can see IP addresses come in on my routers log that are from outside the US, by looking them up, or browsing to them. Sometimes using a ping command to the IP a return will come from another IP. These cyber-criminals try to get in on open ports.

vsftp website…

https://security.appspot.com/vsftpd.html

Zip/unzip is not loaded by default with the Ubuntu Server disc

Zipping and unzipping files from the CLI is an important thing to be able to do.To get it…

sudo apt-get install zip unzip

More info on how to use it….

http://askubuntu.com/questions/86849/how-to-unzip-a-zip-file-from-the-terminal

 

dos2unix

Editing shell or config files on a Windows machine, presents you with the CR-LF and LF issue, for Win and UNIX respectively. Scripts won’t run, problems happen with config files when they are not in the right format. Frequently I encounter this when I coy and paste some code from the Web into eMacs or Notepad, then save it on the Linux server. Then I need to execute dos2unix on it to make it run right.

UNIX and DOS endlines

I had a brain dead moment where I forgot about the entire UNIX and DOS endline thing when I was working on getting the server to auto shutdown.
So when I grabbed the autosuspend script with copy and paste and I brought it into eMacs in Windows, saved it to my /files/public folder on the server and tried to execute it. Lots of $’\r’: command not found.

The solution is to use dos2unix to convert the endlines, if you don’t have it, just do…

sudo apt-get install dos2unix

Then do dos2unix filename and it will modify it in place. Which is good but beware of this default behavior. It does have other options, which can be explored using dos2unix –help.

It’s one and only job is to remove CR-LF (Carriage Return-Line Feed )and just leaving LF ( Line Feed ) as UNIX/Linux wants it to be. If a file acts screwy when brought in from Windows it is most likely this issue. I even had to do it on the autosuspend.conf file!

You can always check a file with the command

cat -e filename

BAD example…

#!/bin/bash^M$
 ^M$
 # Source the configuration file^M$
 . /etc/autosuspend.conf^M$
 ^M$

GOOD example….

#!/bin/bash$
 # Source the configuration file$
 . /etc/autosuspend.conf$
 $

The caret M$ is DOS, $ is UNIX.

Emails using ssmtp

It is great that CRON and other applications send an email to the root on a Linux server, which can be read simply by using mailx from the CLI. But, what if you are not logging into the machine very often at all. Using ssmtp might work well for those situations. Even my Netgear N150 router has something similar as far as sending email. On the router, you input email account settings on it and will email you the log file and other information you would like at regular intervals. Ssmtp may be of interest to me with regards to the server at some point and I have noted it for reference.

It would be interesting and a great idea to have the server be able to send emails of certain things, issues it may be encountering.

This looks interesting, I might do this at some point….

How to send email alerts from Ubuntu Server using ssmtp