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ASUS EeePC900 Performance BOOOOOST

Nov
28

I own ASUS EeePC 900, a small notebook of 8.9 inches screen and I was very satisfied of its mobility use and its power as a computer. However, there was a big problem that I had noticed but soon I managed to solve it.

Symptom:

My notebook was using Windows XP with 1Gb RAM and the CPU at 0.9 GHz, it was somehow “slow”, insufficient in its use. This low performance made me nervous sometimes and I was feeling like my notebook was loosing its power.

Solution:

The solution to this problem was to use Linux based OS as it is Ubuntu. So, at the moment that I had installed Ubuntu in my ASUS 900, everything worked perfect and made my life easier. The computer was very fast and its RAM and processor were good enough for me to perform all kind of functionalities without having problems.

And generally, the choice of Linux based OS in notebooks like that (ACER, LG etc.), is a good way in order to avoid performance problems.

ASUS EeePC900, Performance

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Posted in Computing, How To, Linux, Software, Technical, Windows by Goold| No Comments »

rdiff-backup through gateways using ssh tunnels and remote-schema

Sep
17

Backing-up your workstation off-site on a backup server is generally a good idea. However when both the target and source are behind firewalls, it can be tricky to setup, assuming that you do not want to reconfigure your firewalls to forward ports in either end.

In this article I demonstrate a way to achieve this using rdiff-backup, assuming that both (the workstation and backup server) can be accessed via ssh through their gateways. In this case both source and destination have ssh server installed which are simply not accessible directly from the outside world. However you can reach them if you first ssh to their gateways and then ssh to the final destination.

rdiff-scenario

(Note: The easy solution would be to setup some sort of forwarding to one of the firewalls but if the IT support is incompetent to do so, afraid not.)

rdiff-backup is an excellent tool to perform incremental backups of your valuable data. The basic function of rdiff-backup is to copy all the data from a source directory to the target and subsequently only records differences (diffs) of the files/directories which have changed and creates a snapshot. It is important to understand its advantage over other backup methods such as rsync and this is that it does not only syncs the two directories, but it also keeps the history of the changed files, in case you want to retrieve an older snapshot of your data. Finally the tool would not be so useful if it could not operate over that network.

A typical rdiff-backup command would look like this:

rdiff-backup source destination

The source and destination can either be a a local directory (/path/to/directory) or remote directory (hostname::/path/to/directory) the source and destination arguments are same as those used in scp but you must use double colon character to separate the host name from the path when defining remote directories.

For the discussion purposes let’s assume that the back-up server initiates the backup, retrieves the snapshot and exits. The host name of the workstation we have the original data is workstation and that of the remote gateway is remoteGateway. A command like this will fail because the workstation can not be accessed directly with ssh.

rdiff-backup workstation::/path/to/original/data /path/to/backup

The trick is to use ssh tunnels to reach the workstation. On the back-up server open a terminal and run the command

ssh remoteGateway -L localhost:8000:workstation:22

This will create an interface to the workstation’s ssh server on the backup server (localhost) which operates on port 8000 instead of 22 where ssh normally runs. This command creates a tunnel and any traffic send to localhost port 8000 will be forward through the ssh tunnel between the back-up server and the remoteGateway to the workstation. Hence if you open another terminal and issue the following command you will reach the workstation’s ssh server.

ssh -p8000 localhost

So now you can run rdiff-backup on localhost port 8000 which is actually the workstation. But you need one more trick to make it work. You have to tell rdiff-backup that the ssh sever runs on port 8000. This is done using the switch remote-schema. A command similar to this one will start the back-up process.

rdiff-backup -v6 –print-statistics –remote-schema ‘ssh -p8000 %s rdiff-backup –server’ localhost::/path/to/original/data /path/to/backup

To automate the process you can create a bash script to open the tunnel for you and then run the rdiff-command. You can put it in your crontab to schedule daily backups.

#!/bin/sh
ssh remoteGateway -L localhost:8000:workstation:22 -N &
sshpid=$!
sleep 5; # Allow some time for tunnel to get established.

rdiff-backup -v6 –print-statistics –remote-schema ‘ssh -p8000 %s rdiff-backup –server’ localhost::/path/to/original/data /path/to/backup

sleep 5; # Allow some time for rdiff-backup to exit
kill $sshpid

Posted in Computing, How To, Linux, Software by Christos| No Comments »

Saving your favourite Youtube videos at your PC

Apr
22

A couple of months ago, Alexandros kept asking me about how he could save a youtube video at a local hard drive. My answer was just “I don’t know”, although I found this question rather interesting.

I recently remembered this question and after a short research I noticed that this is rather simple and you can do that with more than one way.

We present here three different ways for downloading videos from your favourite video sharing site and you can choose and go on with the one which is more convenient to you.

In any case, you need to download the FLV Player for playing back the .flv files.

Read the rest of this entry »

Posted in Computing, How To by Kostakiss| 6 Comments »

Producing tables in LaTex witnin seconds with Excel2Latex V2.0

Jan
14

Writing my report on LaTex, I stuck really hard on the construction of a rather complicated table. Many sites are very helpful for simple tables, but when it comes to more advanced features you cannot find what you need.

Excel2Latex V2.0 is a completely free tool that allows overcoming such problems by producing any kind of tables in MS Excel, and with just one click it generates the appropriate code for LaTex.

The table will appear in LaTex format will not be 100% similar to the one in Excel. You may find some minor things missing, such as either horizontal or vertical lines. However, the main structure is exactly the same and the only thing you need to do is add those lines, by inserting some either \hline or \cline{} commands where appropriate.

Personally, I think that it is a great tool, which saves much of hassle and is able to create any table that you wish, conveniently.

Posted in Computing by Kostakiss| No Comments »

HotEqn -The IMGless Equation Viewer Applet

Jan
07

Some good news for those who use LaTex for word processing and also need to write complicated mathematical expressions.

HotEqn is a well organised and structured help with all you need in a table, providing also further examples. The most impressive feature of the site is that you just write your LaTex code for an equation in a frame and through a Java applet you can see what the result of this code is on the fly. Consequently, this saves a lot of time since there is no need for compiling your code in your machine again and again until you get the desired equation.

Posted in Computing by Kostakiss| No Comments »