Remotely Dispatching Jobs from your Cell Phone
by Michael L Farrell
Okay so perhaps you’ve shelled out the extra bucks for an iphone and you can run just about any app you want on it to connect to your computer. However, if you’re like the rest of us, the only “fancy” thing you can do with your cell phone, besides talk on it, is send emails. This article will teach you how to configure your linux server to respond to emails from your cell phone and execute specific pre-programmed jobs as a result.
The first thing you need to do is configure your server to accept incoming emails. Do this by starting to the “Mail transfer agent” module under yast2 and configuring the Incoming Mail section as follows where here I use “kain” as my local user name.
Next, you should verify that your mail host is correct to your global dns server name for your box. Do this by editing the /etc/postfix/main.cf as root and changing the following line to your correct host name
myhostname = localhost # change this to your globally-accessible dns server name (ie www.mybox.com)
After this, verify the change and restart the postfix service (still under root)
slickbox:/etc/postfix # grep "myhostname = " main.cf myhostname = xxxxx.ath.cx slickbox:/etc/postfix # slickbox:/etc/postfix # rcpostfix restart Shutting down mail service (Postfix) done Starting mail service (Postfix) done slickbox:/etc/postfix #
Now send a test email to your test user from your cell phone and verify its receipt under that user’s account. There may be a delay due to the slow nature of email delivery from some cell phone providers
kain@slickbox:~> You have new mail in /var/spool/mail/kain kain@slickbox:~> mail mailx version nail 11.25 7/29/05. Type ? for help. "/var/spool/mail/kain": 1 message 1 new >N 1 <mycell#>@VTEXT.COM Wed May 14 23:26 21/825 Test ?
Okay it works! On to the procmail stuff.
Configuring the remote jobs
Now we’ll want to set up a pre-programmed list of jobs that can be executed remotely only from our cell phone’s email and only containing special keywords that should be hard to guess for security reasons (for additional security concerns, read “security implications” below).
Create a shell script file in your ~/bin directory for each remote job you want to have available to your cell phone. In this example, I’m configuring a job for remote hibernation for my laptop for energy saving reasons. So I’m creating ~/bin/cellphone_hibernate.sh
Containing the text:
#!/bin/bash powersave -U
Next, I make sure the script is executable
kain@slickbox:~/bin> chmod +x cellphone_hibernate.sh
Now, create a file in your home directory, ~/.procmailrc (the leading dot is important) containing the following
PATH=$HOME/bin:/usr/bin:/usr/ucb:/bin:/usr/local/bin:. MAILDIR=$HOME/Mail # You'd better make sure it exists DEFAULT=$MAILDIR/mbox :0 # Cell phone directive #1 * ^From.<mycell#>@VTEXT.COM * !^execjob1_127850 |cellphone_hibernate.sh
The execjob1_127850 is the “command” that I text from my cell phone. I made sure to follow it by some random magic for some limited amount of security. It acts like a weak password for the command. I also make sure that this command is only valid if sent from my phone’s email address. This is somewhat provider-dependant as my provider (verizon) ends all their emails in vtext.com. If you have too much trouble with this, you can comment the From line with a ‘#’ and make the email work from anywhere if you don’t care about the security implications. The line beginning with a | is the command we execute locally upon receiving the email, which happens to be the script I edited earlier in my ~/bin directory.
Seconds after saving this file, I sent a test email from my cell phone to kain@slickbox with the magic directive and within 1 second my laptop started to suspend! Pretty awesome huh?
You can add as many jobs here as you want and if you’re good with procmail, you can even dispatch jobs that collect data and send reports back to your phone – all autonomously!!
Disclaimer: Please be sure to understand the security implications of enabling remote email delivery and procmail processing on your linux server. You should fully understand what you are doing before following the instructions on this article. I accept no responsibility for any damages or losses resulting from the directions in this article. Use them at your own risk.