Remote cPanel backup via FTP

Here is the scenario:

– Domain that needs to be backed up (public_html, mail, database).
– Only access available via cPanel and FTP.
– Need automated daily full backup.


– Take full backup on server and compress its contents (cronjob on remote server)
– Download via FTP the compressed file to the local machine (cronjob on local machine).
– Delete compressed file.

There might be tools that do this, although I didn’t come across any while looking on the web. I implemented a simple solution based on bash scripts that gets the task done. Goes on the remote server to run as a cronjob. Runs locally (on the machine that will store the backup) as a cronjob.
.netrc: Defines the FTP account details (stored in /home/$user/.netrc)


Gmail SMTP relay with Postfix

The following configuration has been performed in Debian but should apply in any Linux distro with Postfix installation. The task quite simple: use Gmail as SMTP relay for outgoing email traffic.

1) At first place I had to install the following packages and turn off sendmail:

apt-get install postfix mailutils libsasl2-2 ca-certificates libsasl2-modules
service sendmail stop

2) Then edit the configuration file at /etc/postfix/ by adding the following options at the end of the file:

# Gmail SMTP relay
relayhost = []:587
smtp_sasl_auth_enable = yes 
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt
smtp_sasl_security_options =

3) Create the authentication file at /etc/postfix/sasl_passwd and set the right permissions:

[]:587    <username><password>
chmod 400 /etc/postfix/sasl_passwd

Make sure the file is owned by the user who runs the Postfix daemon.
4) Reload Postfix:

service postfix reload

5) Confirm the configuration is actually working by sending a test mail:

echo "Test mail from postfix" | mail -s "Test Postfix"

The sender of the email should be the given Gmail account. Also, in the “Sent” folder of the Gmail account you should see the email you have sent with Postfix.

If your domain is using Gmail’s infrastructure for handling emails, you can replace with your domain and use the corresponding account details.

NOTE: This configuration will be sending any system message as “” and therefore is not advised to be used in multi-user environment.

Java HTTP library

Being in need to issue POST requests from within a Java application, and wanting re-usable code, I created a very simple Java library for issuing POST and GET requests to a remote server.

POST source codeGET source code

Usage (POST example):

POST post = new POST();
post.postRequest("", "param1=foo&param2=bar", "Mozilla/5.0");

In other words, the arguments are:


The output can be manipulated as desired, depending on what you response you except you should use a corresponding element/object.

Java encrypt class

A simple implementation of an encryption class to be used in Java applications for either encrypting strings and calculating files’ fingerprint.

import java.math.BigInteger;

public class Encrypt {

   private FileInputStream fis;

   public Encrypt() { }

   public String encryptString(String input, String salt, String algorithm) {
      String output = null;
      String fullInput = null;

      if (!salt.equals(null)) {
         fullInput = salt + input;
      } else {
         fullInput = input;

      try {
         MessageDigest digest = MessageDigest.getInstance(algorithm);
         digest.update(fullInput.getBytes(), 0, fullInput.length());
         output = new BigInteger(1, digest.digest()).toString(16);
      } catch (NoSuchAlgorithmException ex) {
      return output;

   // Based on:
   public String calculateFingerprint(String fileName, String algorithm) {
      StringBuffer sb = new StringBuffer();
      try {
         MessageDigest md = MessageDigest.getInstance(algorithm);
         fis = new FileInputStream(fileName);
         byte[] dataBytes = new byte[1024];
         int nread = 0;
         while ((nread = != -1) { md.update(dataBytes, 0, nread); }
         byte[] mdbytes = md.digest();
         for (int i = 0; i < mdbytes.length; i++) {
            sb.append(Integer.toString((mdbytes[i] & 0xff) + 0x100, 16).substring(1));
      } catch (Exception ex) {
      return sb.toString();

Link to GiHub repository. The class is intended to be used as a library within Java applications.

Example for encrypting a string:

Encrypt en = new Encrypt();
String encryptedString = en.encryptString(textField.getText().toString(), \
"salt goes here if you want", "md5")));

Example for calculating the fingerprint of a file:

Encrypt en = new Encrypt();
String fingerPrint = en.calculateFingerprint("/path/to/file", sha1);

An ARM comparison: Raspberry Pi vs OpenRD Client

Bellow there’s a comparison between Raspberry Pi (Model B) and OpenRD Client, two low-power ARM SoC (System on a Chip), running Linux (Rasbian and Fedora respectively). I used the EEMBC CoreMark benchmark with default settings for 100000, 1000000 and 2000000 iterations. For each set, each device keep its performance with the same rate of iterations per second. The difference between the devices is at, an average level of, 520 iterations per second. That translates to 1.4x faster in favour of the OpenRD Client.

While OpenRD Client performs better, in terms of efficiency, Raspberry Pi seems to doing much better. In terms of CPU, Raspbeery Pi uses a 700MHz (with the possibility of setting it up to 1GHz) ARMv11 processor while OpenRD Client an older 1.2GHz Marvell Sheeva (ARMv5TE). ARMv11 supports an FPU unlike ARMv5 and that is one of the reasons that Raspberry Pi performs quite well despite its lower specifications. In terms of memory, Raspberry Pi uses 256MB DDR2 800MHz (newer models have 512MB RAM), in share with its relatively powerful GPU, while OpenRD Client uses 512MB DDR2 800MHz. OpenRD Client also provides Gigabit Ethernet as well as many more I/O interfaces. Also, OpenRD has preloaded OS, unlike Raspberry Pi that boots from an SD card. During this benchmark, Raspberry Pi was running Rasbian “Wheezy” (unofficial Debian port to armhf) while OpenRD Client Fedora 8.

(Raspberry Pi diagram –

(OpenRD Client Hardware Block diagram –

HPC-Europa2 Virtual Cluster liveDVD – milestone6 (final release)

The JRA2 team is proud to announce the release of HPC-Europa2 live DVD milestone 6. You can download milestone 6 ISO image (compressed with size 1.7 GB) from the below links:

CINECA (Italy) –
EPCC (Scotland) –
HLRS (Germany) –

Release Note for Milestone 6
The Virtual Cluster liveDVD:
* provides tools and libraries that are installed and used at the partner sites.
* emaulates the environment of the platforms available at HPC-Europa centers.
* allows hands-on building of a virtual cluster.

The liveDVD contains training and dissemination material published by the
HPC-Europa2 project, including material from the partner centers such as slides,
video tutorials and example code. Optional access to a source code repository enables
the migration of code and data from the Virtual Cluster to the user account created
on the HPC-Europa machines.

The liveDVD is based on SliTaz GNU/Linux, a free operating system, working completely
in RAM and booting from a removable media. The file size of the SliTaz GNU/Linux
3.0 ISO image is 29 MB. Hence, it leaves plenty of space for adding tools, libraries
and training material into this liveDVD. The SliTaz system is quick, responsive, and clean.
A lightweight and elegant desktop is included as well in the 29MB ISO image.

The milestone 6 ISO image has roughly the size of 3.8 GB including several tools
and libraries, as well as training material. Moreover, it contains a documentation
of how to build a virtual cluster using VirtualBox, and HPC-Europa2's Science and
Supercomputing in Europe research highlights for 2009 and 2010. Finally, this milestone
release addresses several bug fixes, such as firefox with flash support and
build scripts for Torque.

Since the previous release (milestone 5), existing packages have been updated, such as:
* MPICH2 to version 1.4.1p1
* Firefox to version 9.0.1 with flash support.
* Paraver to support the updated version of MPICH2.

In addition, this release has added several new packages:
* lava-1.0.6: Platform Lava - an open source version of Platform Load Sharing Facility (LSF).
* info (texinfo-4.13a) and man pages (man-db- and man-pages-3.35) for Linux documentation.
* Abiword and Gnumeric for office word documents and spreadsheets.
* Compiler wrappers (based on gcc and gfortran) to emulate Intel, IBM and NEC SX compilers.

You can download milestone 6 ISO image (compressed - size 1.7 GB) from the below link:

System Requirements
* A laptop or computing with a DVD drive.
* Intel or AMD processor with a hardware virtualization support when using KVM
  and libvirt. Otherwise, this liveDVD can be run under VirtualBox or VMware or similar.

Known Issues
* PGI compilers require a license file in order to work (not included in this milestone).
* Totalview requires a license file in order to work (not included in this milestone).
  For requiring a demo license visit:
* On a MacBook Pro laptop, the mousepad does not work. Need to use an USB mouse
* Resizing video screen on VLC causes an unexpected exit of the program.
* VLC has no sound for viewing mkv videos.
* VLC cannot stream files or view incoming streams.

This work was carried out under the HPC-EUROPA2 project (project number: 228398),
with the support of the European Community - Research Infrastructure Action of the FP7.

Shell script for NITROX calculations

The following script was developed for providing quick calculations over NITROX diving. It provides an interactive menu for the following calculations:

1 – Maximum Operational Depth (MOD)
2 – Operational Depth (OD)
3 – Best mix
4 – Equivelant Air Depth (EAD)
5 – Nitrogen percentage compared to Air
6 – Oxygen partial pressure (PO2)
7 – Central Nervous Systems Toxicity (CNS)
8 – Absolute pressure

# Copyright (C) 2011  Panagiotis Kritikakos <>           #
#                                                                          #
#    This program is free software: you can redistribute it and/or modify  #
#    it under the terms of the GNU General Public License as published by  #
#    the Free Software Foundation, either version 3 of the License, or     #
#    (at your option) any later version.                                   #
#                                                                          #
#    This program is distributed in the hope that it will be useful,       #
#    but WITHOUT ANY WARRANTY; without even the implied warranty of        #
#    GNU General Public License for more details.                          #
#                                                                          #
#    You should have received a copy of the GNU General Public License     #
#    along with this program.  If not, see <>. #

echo "
Every individual diver is responsible for planning
and conducting dives using SCUBA equipment up to the
trained and certified qualification he or she holds.

The creator of this program does not have any
responsibility for symptoms of Decompressions Sickness
when the suggested values of this program are used
for conducting a dive.
   echo -n "NITROX mix: "; read mix
   MOD=`echo "scale=2; (((1.6/$mix)*10)*100)-10" | bc`
   echo " MOD for $mix NITROX: $MOD"

   echo -n "NITROX mix: "; read mix
   OD=`echo "scale=3; (((1.4/$mix)*10)*100)-10" | bc`
   echo " OD for $mix NITROX: $OD"

   echo -n " Depth: "; read depth
   BESTMIX4=`echo "scale=2; 1.4/(($depth/10)+1)" | bc`
   BESTMIX6=`echo "scale=2; 1.6/(($depth/10)+1)" | bc`
   echo " Best mix for 1.4 PO2: $BESTMIX4"
   echo " Best mix for 1.6 PO2: $BESTMIX6"

   echo -n " Depth: "; read depth
   echo -n " NITROX: "; read nitrox
   EAD=`echo "scale=2; ((((1-($nitrox/100))*4)/0.79)-1)*10" | bc`
   echo " EAD for $depth MSW and NITROX $nitrox: $EAD"

   echo -n " NITROX: "; read nitrox
   EQU=`echo "scale=2; 100-(((1-($nitrox/100))/0.79)*100)" | bc`
   echo " ${EQU}% less nitrogen"

   echo -n " Depth: "; read depth
   echo -n " NITROX: "; read nitrox
   PO2=`echo "scale=2; (($depth+10)/10)*($nitrox/100)" | bc`
   echo " PO2 at $depth MSW for NITROX $nitrox: $PO2 ATM"

   echo -n " PO2 [1.4, 1.5, 1.6]: "; read po2
   echo -n " Duration: "; read duration
   if [ "$po2" == "1.4" ]; then
      CNS=`echo "scale=2; ($duration/150)*100" | bc`
   elif [ "$po2" == "1.5" ]; then
      CNS=`echo "scale=2; ($duration/120)*100" | bc`
   elif [ "$po2" == "1.6" ]; then
      CNS=`echo "scale=2; ($duration/45)*100" | bc`
      echo " Choose between 1.4, 1.5 and 1.6 PO2"
      exit 1
   echo " CNS for $duration minutes and $po2 PO2: ${CNS}%"

   echo -n " Depth: "; read depth
   ABS=`echo "scale=2; (($depth/10)+1)" | bc`
   echo " Absolute pressure at depth of $depth MSW: $ABS ATM"

echo " 1 - Maximum Operational Depth (MOD)"
echo " 2 - Operational Depth (OD)"
echo " 3 - Best mix"
echo " 4 - Equivelant Air Depth (EAD)"
echo " 5 - Nitrogen percentage compared to Air"
echo " 6 - Oxygen partial pressure (PO2)"
echo " 7 - Central Nervous Systems Toxicity (CNS)"
echo " 8 - Absolute pressure"
echo -n " Function: "; read option
case "$option" in
	  echo " Please choose a valid option from the menu"
	  exit 1