Category Archives: Tips

sh, bash, dash and Ubuntu

Posted on by
Reply

Hi!
I wanted to install a quite old package in my ubuntu computer using the .sh file I downloaded from their website. So, I tried typing in terminal:

sudo ./package_name.sh

and I got:

/bin/sh: 0: Can’t open ./package_name.sh

Briliant! Since you are here, you are probably looking for a fix.

The problem stems from the fact that Ubuntu uses dash as the default shell and your script is written with another shell in mind. The most usual is bash (sh).

So type in a terminal window:

sudo bash ./package_name.sh

This will force ubuntu to run the script using bash.

Enjoy!
Vasilis

PSAD Quick Fix

Posted on by
Reply

I like psad. I use it often and I find the email reports really handy.

Here is an issue I faced in Ubuntu and the solution:

Instead of the reports I received an email with the following contents:

[-] You may just need to add a default logging rule to the /sbin/iptables
‘filter’ ‘INPUT’ chain on oxide-server.  For more information,
see the file “FW_HELP” in the psad sources directory or visit:

http://www.cipherdyne.org/psad/docs/fwconfig.html

[-] You may just need to add a default logging rule to the /sbin/ip6tables
‘filter’ ‘INPUT’ chain on oxide-server.  For more information,
see the file “FW_HELP” in the psad sources directory or visit:

http://www.cipherdyne.org/psad/docs/fwconfig.html

 

I found on the web several people with the same problem, so here is what worked for me:

  1. Enable ufw logging. Type in console as root: ufw logging on
  2. Type as root:
    iptables -A INPUT -j LOG
    iptables -A FORWARD -j LOG
    ip6tables -A INPUT -j LOG
    ip6tables -A FORWARD -j LOG
  3. Open /etc/ufw/before.rules and type before the COMMIT directive:
    -A INPUT -j LOG
    -A FORWARD -j LOG
  4. Open /etc/ufw/before6.rules and type before the COMMIT directive:
    -A INPUT -j LOG
    -A FORWARD -j LOG
  5. Restart ufw by typing as root:
    ufw disable
    ufw enable
  6. Test if it worked:
    psad –fw-analyze

I know that some parts appear to do very similar things but for a strange reason it worked only after the exact above procedure.

Hope it helps!
Vasilis

 

 

SWikipedia: S (named ess spelled ‘es’- in compound words; plural esses, forms/script: ) is the nineteenth (19th) letter in the ISO basic Latin alphabet. →

Image resize & JPG to PDF

Posted on by
1

I am preparing some applications and I needed to scan several documents and upload them online in PDF format. The problem is that there is an upload limit of 3MB per PDF document. Since I like to have my files well organized and maintain digital records for everything I always use the maximum resolution (600dpi) when scanning. This, of course, results in 5-6 MB images.

So, I had to resize multiple JPG documents and then combine them in 6-7 pdf files.

The tools I found extremely handy for this purpose were:

  • FastStone Photo Resizer: For resizing multiple files in a fraction of their original size. Worked like a charm! (http://www.faststone.org/FSResizerDetail.htm)
  • FM JPG To PDF Free: For combining the images to a single PDF. Pay close attention (as always?) when installing the application and uncheck the installation of unnecessary features like “Babylon search”, unless you really like them. (http://www.fm-pdf.com/FM-JPG-To-PDF-Converter-Free-Setup.exe)

From this point the procedure was easy an it was more drag n’ drop.

Let me know if you are aware of better alternatives!

Have fun!
Vasilis

P.S.: Maybe next time I should try using a loseless image format, like PNG, instead of JPG.

PDF cracking? Don’t bother!

Posted on by
2

Sometimes people pay too much attention to details that tend to lose the complete picture. This is what happened to me when I was loooking for a way to copy a part of an article (for some notes I kept) from a “protected” pdf file. I tried to find a way to “crack” the protection instead of thinking how pdf readers operate.

First of all, an advice:
Don’t use the following trick to steal other people’s work! This is called plagiarism and may lead you in really embarassing situations.

It is possible that you came here looking for a pdf cracker or a way to trick adobe pdf reader (or similar software) but I will show you a different approach.

Ok, let’s explain how this thing works. Since you can read the text from the pdf file, the information is not really encrypted, in contrast there is just a “special instruction set” that tells the reader if an operation (selection, copy, print etc) is allowed.  What if the PDF reader ignores this “instruction set”?  Then all operations are allowed and you are free to perform all operations as with any non-protected document!

So, all you have to do is to find a pdf reader that ignores adobe’s “special instructions”.
In ubuntu, I use the preinstalled Evince and it works fine.

I am not aware of an equivalent reader in windows, but I’ll do some research…

Hope it helps,
Vasilis