Keep your SSH sessions alive

Most Internet service provider will try shutdown active Internet connections after a view minutes to prevent their network from streaming videos or other bandwidth killers. This happens often because of some router setting you can’t change. As a web developer your SSH session (and other active connections) will freeze, if you stop working in the terminal window for just 5 minutes or by getting a fresh cop of coffee.

To get rid of this problem you need to change your SSH config file, enter the following inside to the terminalwindow

sudo nano /etc/ssh/ssh_config

and add this setting to the end of the file

ServerAliveInterval 60

Safe your file and start a new SSH session which will stay active because the client sends every 60 seconds a bit of data to the server.
Check also this article for more information.

Optimize Apache and MySQL for a 256MB VPS

For small websites or not so popular WordPress blogs a small VPS with only 256MB of RAM should be enough. If you’ve followed this guide to install a Ubuntu web server you need to optimize your server a little bit.

Start installing MySQLtuner

Download the Perl script to your (admin) home directory:

wget http://mysqltuner.pl/mysqltuner.pl

Create also a file nano .my.cnf and add this code:

[client]
user=someusername
pass=thatuserspassword

After running MySQLtuner script perl mysqltuner.pl you should get this warning:

Reduce your overall MySQL memory footprint for system stability

To resolve this an other memory related issues we need to optimize the MySQL database settings. Continue reading Optimize Apache and MySQL for a 256MB VPS

SSH Authentication without entering a password

Follow the instructions below to create and install a SSH public key on your remote server. After you followed these steps your able to login via SSH without entering a password. This is extremely useful for backups with rsync or for other automatic tasks you like to execute.

  1. Change to your user’s home directory (local system)
    cd ~
  2. create a pair of private keys
    ssh-keygen -f .ssh_key -t rsa -N ''
  3. *** upload the public key to the remote system using rsync via SSH
    rsync -e ssh ~/.ssh_key.pub [email protected]:key1.pub
  4. login to your server via SSH using the command line or Putty
    ssh [email protected]

    (you need to enter your password too)

  5. check if the .ssh directory exists, if not create it
    mkdir .ssh
  6. add the public key to the user authorized key files
    cat key1.pub >> .ssh/authorized_keys
  7. remove the uploaded key from your home directory (remote system)
    rm key1.pub
  8. test your new “private” connection
    rsync -avz -e "ssh -i .ssh_key" "someFolder" [email protected]

Now you’re able to access the remote system (YourServer) from your local system without using a password. This tutorial is for Linux only.

*** UPDATE: 12th december 2011

If you can’t create a persistent SSH connection to you backup server this way you need a small workaround:

After the creation of your “local” keys you need to download the “authorized_keys” file from the backup server

rsync -e ssh [email protected]:.ssh/authorized_keys ~/authorized_keys

(check the exact locations first)

Now add your public key to the downloaded file

cat .ssh_key.pub >> authorized_keys

Upload the modified “authorized_keys” file to the backup server

rsync -e ssh ~/authorized_keys [email protected]:.ssh/authorized_keys

Remove the downloaded file and test you connection like described in step 8.

How-to create a virtual host in Apache (Ubuntu)

You will find on most Linux based web hosts a directory which is called “sites-available” (inside /etc/httpd/ or /etc/apache2/). Create a configuration file with the name “domain.com” for your host and add this code:

ServerName domain.com
ServerAlias www.domain.com
ServerAdmin [email protected]
DocumentRoot /home/user/domain.com/public_html/
ErrorLog /var/log/apache2/domain.com-error.log
# Possible values include: debug, info, notice, warn, error, crit, alert, emerg
LogLevel warn
CustomLog /var/log/apache2/domain.com-access.log combined

Create the directory for your web host and activate the host with a2ensite domain.com and reload your apache engine.

How-to restore email messages from Uebimiau or T-dah webmail

I have a few servers where DirectAdmin is used as the control panel and it seems that Uebimiau (or T-dah) is used as default webmail client. Unlike other e-mail clients Uebimiau will download your e-mail messages like a local mail client and stores them in Uebimiau directories. That will say if you need to check your mail from some other computer using Uebimiau as web mail client, you can’t download them again on your “regular” computer using Outlook for example. Continue reading How-to restore email messages from Uebimiau or T-dah webmail