Posts Tagged ‘current situation’

Editting binary files in console and GUI on FreeBSD and Linux

Thursday, April 26th, 2012

Reading Time: 7minutesI’ve recently wanted to edit one binary file because there was compiled in the binary a text string with a word I didn’t liked and therefore I wanted to delete. I know I can dig in the source of the proggie with grep and directly substitute my “unwatned text” there but I wanted to experiment, and see what kind of hex binary text editors are for Free OSes.
All those who lived the DOS OS computer era should certainly remember the DOS hex editors was very enjoyable. It was not rare case, where in this good old days, one could simply use the hex editor to “hack” the game and add extra player lives or modify some vital game parameter like put himself first in the top scores list. I even remember some DOS programs and games was possible to be cracked with a text editor … Well it was times, now back to current situation as a Free Software user for the last 12 years it was interesting to see what is the DOS hexeditor like alternatives for FreeBSD and Linux and hence in this article I will present my findings:

A quick search in FreeBSD ports tree and Debian installable packages list, I’ve found a number of programs allowing one to edit in console and GUI binary files.

Here is a list of the hex editors I will in short review in this article:

  • hexedit
  • dhex
  • chexedit
  • hte
  • hexer
  • hexcurse
  • ghex
  • shed
  • okteta
  • bless
  • lfhex

1. hexedit on Linux and BSD – basic hex editor

I’ve used hexedit already on Linux so I’ve used it some long time ago.

My previou experience in using hexedit is not too pinky, I found it difficult to use on Redhat and Debian Linux back in the day. hexedit is definitely not a choice of people who are not “initiated” with hex editting.
Anyways if you want to give it a try you can install it on FreeBSD with:

freebsd# cd /usr/ports/editors/hexedit
freebsd# make install clean

On Debian the hexedit, install package is named the same so installation is with apt:

debian:~# apt-get –yes install hexedit

hexedit screenshot Debian Linux Squeeze

2. Hex editting with chexedit

I’ve installed chexedit the usual way from ports:

freebsd# cd /usr/ports/editors/chexedit
freebsd# make install clean

chexedit is using the ncurses text console library, so the interface is very similar to midnight commander (mc) as you see from below’s screenshot:

Chexeditor FreeBSD 7.2 OS Screenshot

Editting the binary compiled in string was an easy task with chexedit as most of the commands are clearly visible, anyways changing a certain text string contained within the binary file with some other is not easy with chexedit as you need to know the corresponding binary binary value representing each text string character.
I’m not a low level programmer, so I don’t know the binary values of each keyboard character and hence my competence came to the point where I can substitute the text string I wanted with some unreadable characters by simply filling all my text string with AA AA AA AA values…

chexedit on Debian is packaged under a deb ncurses-hexedit. Hence to install it on Deb run:

debian:~# apt-get –yes install ncurses-hexedit

Further on the binary to run chexedit on binary contained within ncurses-hexedit is:

debian:~# hexeeditor

3. Hex Editting on BSD and Linux with hte

Just after trying out chexedit, I’ve found about the existence of one even more sophisticated hexeditor console program available across both FreeBSD and Linux.
The program is called hte (sounds to me a bit like the Indian word for Elephant “Hatti” :))

hte is installable on Debian with cmd:

debian:~# apt-get install ht

On FreeBSD the port name is identical, so to install it I execed:

freebsd# cd /usr/ports/editors/hte
freebsd# make install clean

hte is started on Debian Linux (and presumably other Linux distros) with:

$ hte

On FreeBSD you need to run it with ht command:

freebsd# ht

You see how hte looks like in below screenshot:

ht has the look & feel like midnight commander and I found it easier to use than chexedit and hexeditor
4. hexer VI like interface for Linux

As I was looking through the available packages ready to install, I’ve tried hexer

debian:~# apt-get install –yes hexer

hexer does follow the same standard commands like VIM, e.g. i for insert, a for append etc.

Hexer Debian Linux vim like binary editor screenshot

It was interesting to find out hexer was written by a Bulgarian fellow Petar Penchev 🙂
(Proud to be Bulgarian)

http://people.freebsd.org/~roam/ – Petar Penchev has his own page on FreeBSD.org

As a vim user I really liked the idea, the only thing I didn’t liked is there is no easy way to just substitute a string within the binary with another string.

5. hexcurse another ncurses library based hex editor

On Deb install and run via:

debian:~# apt-get –yes install hexcurse
debian:~# hexcurse /usr/bin/mc

Hexcurse Debian Linux text binary editor screenshot

hexcurse is also available on FreeBSD to install it use cmd:

freebsd# cd /usr/ports/editors/hexcurse
freebsd# make install clean
….

To access the editor functions press CTRL+the first letter of the word in the bottom menu, CTRL+H, CTRL+S etc.
Something I disliked about it is the program search is always in hex, so I cannot look for a text string within the binaries with it.

6. ghex – Editting binary files in graphical environment

If you’re running a graphical environment, take a look at ghex. ghex is a gnome (graphical hex) editor.Installing ghex on Debian is with:

debian:~# apt-get –yes install ghex
….

To run ghex from terminal type:

debian:~# ghex2

GHex2 GNOME hex binary editor screenshot

To install ghex on FreeBSD (and I assume other BSDs), install via port:

freebsd# cd /usr/ports/editors/ghex
freebsd# make install clean

Gnome hex editor have plenty of tools, useful for developers to debug binary files.

Some nice tools one can find are under the the menus:

Windows -> Character Table

This will show a complete list of each keyboard sent character in ASCII, Hex, Decimal, Octal and Binary

Screenshot ghex Character table Debian Linux

Another useful embedded tool in ghex is:

Windows -> Type Convertion Dialog

Ghex type convertion dialog screenshot

Note that if you want to use the Type Convertion Dialog tool to find the representing binary values of a text string you will have to type in the letters one by one and save the output within a text file and later you can go and use the same editor to edit the text string within the binary file you like.

I’m not a programmer but surely for programmers or people who want to learn some binary counting, this 2 ghex edmebbed tools are surely valuable.

To conclude even though there are plenty of softwares for hex editting in Linux and BSD, none of them is not so easy to use as the old DOS hexdedit tool, maybe it will be a nice idea if someone actually rewrites the DOS tool and they package it for various free operating systems, I’m sure many people will find it helpful to have a 1:1 equivalent to the DOS tool.

7. Shed pico like interfaced hex editor

For people, who use pico / nano as a default text editor in Linux shed will probably be the editor of choice as it follows the command shortcuts of picoOn Deb based distros to install it run:

debian:~# apt-get install –yes shed

shed pico like hex binary editor Linux

Shed has no BSD port as of time of writting.8. Okteta a KDE GUI hex editor

For KDE users, I found a program called okteta. It is available for Deb based Linuxes as deb to install it:

debian:~# apt-get –yes install okteta

Screenshot Okteta Debian GNU / Linux Squeeze

As of time of writting this article there is no okteta port for BSDs.
Okteta has plenty of functions and even has more of a functions than ghexedit. Something distinctive for it is it supports opening multiple files in tabs.

9. lfhex a large file text editor

lfhex is said to be a large (binary) file text editor, I have not tested it myself but just run it to see how it looks like. I don’t have a need to edit large binary files too, but I guess there are people with such requirements too 🙂

lfhex - Linux The Large file hex editor

To install lfhex on Debian:

debian:~# apt-get install –yes lfhex

lfhex has also a FreeBSD port installable via:

freebsd# cd /usr/ports/editors/lfhex
freebsd# make install clean

10. Bless a GUI tool for editting large hex (binary) files

Here is the description directly taken from the BSD port /usr/ports/editors/bless

Bless is a binary (hex) editor, a program that enables you to edit files asa sequence of bytes. It is written in C# and uses the Gtk# bindings for theGTK+ toolkit.

To install and use ot on deb based Linuxes:

debian:~# apt-get install –yes bless
….

On BSD installation is again from port:

freebsd# cd /usr/ports/editors/bless
freebsd# make install clean
….

Something that makes bless, maybe more desirable choice for GUI users than ghex is its availability of tabs. Opening multiple binaries in tabs will be useful only to few heavy debuggers.

Bless GUI hex editor Debian Linux tabs opened screenshot

11. Ghextris – an ultra hard hacker tetris game 🙂

For absolute, hacker / (geeks), there is a tetris game called ghextris. The game is the hardest tetris game I ever played in my life. It requires more than regular IQ and a lot of practice if you want to become really good in this game.

To enjoy it:

debian:~# apt-get –yes install ghextris

Ultra hrad hardcore hackers game ghextris screenshot

Unfortunately there is no native port of ghextris for BSD (yet). Anyhow, it can be probably run using the Linux emulation or even compiled from source.
Well that’s all I found for hexedit-ing, I’ll be happy to hear if someone can give me some feedback on his favourite editor.

Best software available today for Linux video Desktop capturing on Debian

Tuesday, April 19th, 2011

Reading Time: 4minutes
I’ve been experimenting since some time in order to understand better what is the current situation with Video Desktop Capturing Software available today for Linux and FreeBSD.

My previous investigations has led me to write an article about xvidcap calledHow to make Video from your Linux Desktop with xvidcap

Though xvidcap works pretty well, it is currently uncapable of capturing the audio stream of a Linux Desktop env and hence part of the interactivity of the videos is missing when used.

A bit of further investigation on the topic has pointed me to 3 free software programs which are capable to record Desktop environment on Linux with sound embedded

The interesting screen video capturing Desktop tools I’ve found are:

1. recordMyDesktop
2. Istanbul
and
3. vnc2swf

Installing them on a Debian based distribution is pleasable, as there are installable debian packages of each one which I installed easily with apt:

debian:~# apt-get install istanbul recordmydesktop gtk-recordmydesktop vnc2swf

RecordMyDesktop‘s package contains a command line little tool which when started directly starts capturing video and audio of the Linux Desktop. After a Ctrl+C is pressed the program quits, saves and encodes the video in ogg-encapsulated theora-vorbis file format.

Here is the output I got in saving a sample file by launching recordmydesktop without any arguments:

hipo@debian:~/Desktop$ recordmydesktop
Initial recording window is set to:
X:0 Y:0 Width:1024 Height:768
Adjusted recording window is set to:
X:0 Y:0 Width:1024 Height:768
Your window manager appears to be Metacity

Initializing…
Buffer size adjusted to 4096 from 4096 frames.
Opened PCM device hw:0,0
Recording on device hw:0,0 is set to:
2 channels at 22050Hz
Capturing!
Broken pipe: Overrun occurred.
Broken pipe: Overrun occurred.
Broken pipe: Overrun occurred.
^C
*********************************************

Cached 5 MB, from 207 MB that were received.
Average cache compression ratio: 97.3 %

*********************************************
Saved 69 frames in a total of 69 requests
Shutting down..Broken pipe: Overrun occurred.

STATE:ENCODING
Encoding started!
This may take several minutes.
Pressing Ctrl-C will cancel the procedure (resuming will not be possible, but
any portion of the video, which is already encoded won’t be deleted).
Please wait…
Output file: out.ogv
[100%]
Encoding finished!
Wait a moment please…

Done.
Written 692529 bytes
(635547 of which were video data and 56982 audio data)

Cleanning up cache…
Done!!!
Goodbye!

The captured file as I you see in the above output is saved in file out.ogv

RecordMyDesktop has also a GUI interface (written in Python) called gtk-recordmydesktop

Below you see a screenshot of the GUI gtk-recordmydesktop:

RecordMyDesktop GTK interface entry screen

gtk-recordmydesktop is a super-easy to use as you already see in the picture, you can either configure it with Advanced button or use Save As button to select where you want the Desktop captured video and audio to be stored.

In Debian Squeeze 6.0, the Advanced GUI button interface button is not working but that’s not such an issue, as the rest of the buttons works fine.
After the recordmydesktop‘s Record button is pressed it will start capturing from your Desktop and the window seen in the above screenshot will disappear/hide in the system tray:

recordmydesktop recording minimized in system tray
When you press over the white little square in the system tray the screen capturing will be interrupted and a window will pop-up informing you that the captured video and audio is being encoded, here is another screenshot of recordmydesktop encoding a saved Desktop video stream:

recordmydesktop saving captured desktop video

After the final .ogv file is encoded and saved to further transfer it into (.flv) I used ffmpeg;

debian:~# ffmpeg -i test.ogv test.flv
...

Now let’s evaluate a bit on the the final results, the produced test.ogv‘s synchronization between sound and video was not good as the sound was starting earlier than the video and therefore even though recordmydesktop used to be highly praised on the net, the proggie developers still needs to do some bug fixing
Further on, I continued and (gave the other Desktop screen capturer) Istanbul a try hoping that at least with it the video and audio of my Linux desktop will be properly captured. But guess what, the results with Istanbul was even more unsatisfactory as the produced videos and sounds, were slow and a lot of frames from the screens were missing completely.
Moreover the sound which was supposed to accompany the video was completely 🙁

Thus I will skip on talking about Istanbul as in my view, this piece of software is far away from being production ready.

I also tested vnc2swf , launched it by: pressing alt+f2 and typing in vnc2swf in GNOME’s run application prompt, just to be surprised by an error …:

vnc2swf error no 111 Connection refused

The reason for this error is caused by the xserver (Xorg) port 5900 is being closed by default on Debian

However this error is easily solvable, by making the Xserver to listen to a the port 5900, to make the Xorg server on Debian to listen on this port you need to edit the file:

/etc/X11/xinit/xserverrc

and change inside it:

exec /usr/bin/X -nolisten tcp "$@"

with:

exec /usr/bin/X "$@"

and either reboot your Linux or restart only the Xorg server by pressing Ctrl+Alt+BackSpace

Now let me conclude, the results from my desktop video screen capturing experiments prooved that vnc2swf is superior (as it is capable of properly saving a movie with sound and video from a Linux Desktop). It appears this soft is actually the best one you can use to make a video of your Linux desktop.

Sadly my testing has proven that Linux is still lacking behind Windows and Mac in even doing the most simple tasks …
Let’s hope that situation will get better soon and Gnome or KDE developers will soon provide us with better software capable to save properly a video and audio captured from the Linux Desktop.