sudo apt-get install youtube-dl
Let’s imagine you would like to download the following video: http://www.youtube.com/watch?v=2leg8mUE9rs (this is part of Military Parade at Red Square in Russia at 9th of May 2010). Just run youtube-dl download utility as follows:

youtube-dl http://www.youtube.com/watch?v=2leg8mUE9rs

and in a few minutes you will get 2leg8mUE9rs.flv file that could be viewed using almost any video player like my favorite one VLC.

Today it came to my mind that it is time to make sensitive information stored on my usb flash drive encrypted but still transportable and easy to use. But I don’t want to have whole my 32 GB usb drive fully encrypted using truecrypt or something similar. It is just toooo slow. I also don’t want to use GPG for uncompressing files and directories every time I would like to read them and then create new GPG compressed file every time I save changes. This eats too much of my time and system resources. At the same time it is necessary to be able to use that usb drive under windows, mac, linux whatever (read/write files) but still have my directory structure with sensitive files encrypted. Here is the solution: create encrypted filesystem within a file named, say, 16GB.candy.bin that could be stored on regular windows formatted usb flash drive and then mounted under Linux using the password.

When it becomes necessary I can mount that 16GB.candy.bin as the regular ext3 filesystem with all those stuff like permissions, ownership etc. that is available on ext3 but not in FAT or NTFS. On my windows formatted flash drive candy takes only 16 GB so I can use the rest of space to store not so sensitive information like mp3, movies or photos. Moreover I on windows or linux to read it.

Let’s create that 16GB.candy.bin file with encrypted ext3 filesystem (read below explanations below carefully before just to copy/paste commands into CLI):

[root@artemn root]# cd /path/to/candy/

[root@artemn root]# tune2fs -i 0 -c 0 /dev/loop0

Here are some points: using above commands we create encrypted file of 16 GB so if you need to have more or less just change “count=16000″ in dd line. “count=16000″ means 16GB so “count=20″ means 20MB. Path ‘/path/to/candy/’ is for example only so you should change it to real directory that is able to host encrypted file (16 GB in above example). Command losetup is present in most Linux distributions (btw I recommend Ubuntu especially newly released Lucid Lynx) but if it is not use your disro’s packet manager to install it or compile from sources (for super geeks only, Mr. Stallman if you read this article — Hello). Reader, you can replace “/dev/urandom” in dd line with “/dev/zero” that will make that command to finish faster but will lower security level of resulting file (read about AES for better understanding). You will need to enter the password when running losetup command so make sure it safe and long enough like ‘6U2sAsR37Hn8122dGsaPrew1twt’ but not ‘abc123′ or ‘iloveyou’.

Once commands are done you will get 16GB.candy.bin containing encrypted ext3 filesystem. You can store this file where ever you want, say, on a flash drive. If you loose it nobody won’t be able to open it until he (or she!) cracked AES encryption (use long passwords to prevent this). As the next step it is required to mount filesystem and store some files/directories in it:

[root@artemn root]# mkdir -p /mnt/candy

[root@artemn root]# umount /mnt/candy

When you unmount 16GB.candy.bin the changes are already saved there so it’s not required to compress and encrypt anything unlike with GPG.

P.S. This post is inspired by Loopback tricks article. Thanks to the author. Good luck!

#!/bin/bash

WGET="/usr/bin/wget"

$WGET -q --tries=10 --timeout=5 http://www.google.com -O /tmp/index.google &> /dev/null
if [ ! -s /tmp/index.google ];then
	echo "no"
else
	echo "yes"
fi

As you see it tries to download google’s index page, if it’s not empty script returns “yes”, if there is not Internet connection available script will return “no”. If it is impossible to fetch the page in more than 5 seconds script will return “no” as well.

Anything to add? You are welcome!

The !$ command returns the last argument used with a command. But what happens if you have a command that used arguments and you want to reuse just one of them? The !:1 operator returns the argument used in a command. The example in Listing 3 shows how you can use this operator in combination with the !$ operator. In the first command, a file is renamed to a more meaningful name, but to preserve use of the original file name, a symbolic link is created. The file kxp12.c is renamed in a more readable manner, then the link command is used to create a symbolic link back to the original file name, in case it’s still used elsewhere. The !$ operator returns the file_system_access.c argument, and the !:1 operator returns the kxp12.c argument, which is the first argument of the previous command.

Listing 3
$ mv kxp12.c file_system_access.c
$ ln –s !$ !:1

Read more here…

And these days I came across a good article “Shell Games” (by Marcus Nasarek) telling about above mentioned matters…

Both Bash and the Windows Vista PowerShell include commands for navigating directories, managing files, and launching other programs. System administration is an important duty for the shell, and Bash and PowerShell are equipped to help manage systems from the command prompt. Whereas Bash typically relies on a combination of newer tools and classic Unix utilities, the PowerShell has its own set of command-line programs. Windows refers to PowerShell commands as cmdlets. The PowerShell cmdlet called Get-Process is a counterpart to ps, and the cmdlet Get-Content corresponds to less. PowerShell differs significantly from previous Windows command shells. In this article, I look at how Windows Vista PowerShell compares with Bash. Read more >>

More useful links:

1. Microsoft PowerShell official page
2. Bash Reference Manual
3. GNU Bash for Windows

Having a network-enabled root shell in my pocket is great, but being able to pop a root shell on someone else’s iPhone is even better. A few things to keep in mind:

Every process runs as root. MobileSafari, MobileMail, even the Calculator, all run with full root privileges. Any security flaw in any iPhone application can lead to a complete system compromise. A rootkit takes on a whole new meaning when the attacker has access to the camera, microphone, contact list, and phone hardware. Couple this with “always-on” internet access over EDGE and you have a perfect spying device.

Read more… 

Here is a piece of shell code that allows to export ipcad output into sqlite3 database format:

echo "create table traffic (src, dst, pkt, bt);" | sqlite3 /tmp/throttle.db
rsh 127.0.0.1 show ip accounting | grep "^ " | grep -vi source | awk \
'{print"insert into traffic values (\""$1"\",\""$2"\",\""$3"\",\""$4"\");"}' \
| sqlite3 /tmp/throttle.db


To make this working ipcad should be configured not to capture ports and to enable rsh service. In my case ipcad has the following settings set in ipcad.conf:

capture-ports disable;
interface eth0;
rsh enable at 127.0.0.1;
rsh 127.0.0.1 admin;
rsh ttl = 3;
rsh timeout = 30;
pidfile = /var/run/ipcad.pid;
memory_limit = 100m;


and output (rsh 127.0.0.1 show ip accouting) is like:

192.168.0.7      192.168.0.1                 113241           166387462
192.168.0.1      192.168.0.7                  72117             4282846
192.168.0.77     66.235.184.245                2448              821095
66.235.184.245   192.168.0.77                  3995              697371

The main problem is that it sqlite3 is rather slow and it takes eleven (11!!!) seconds to export 1000 entries of ipcad’s output into database. This was got at PC with 1.4Ghz CPU and 512Mb RAM.

If anybody knows how to get it faster, PLEASE LET ME KNOW! Thanks.

Information Improvisation: Traffic Engineering Server is new Solution for Bandwidth Management and QoS. It’s especially suitable for Broadband ISPs and SMEs.

In other words, to create Linux user account with password the following command will be useful:

useradd -m -p encryptedPass username

I know at least two ways to get password encrypted. The first one is to use perl crypt(); function:

perl -e 'print crypt("password_to_be_encrypted", "salt"),"\n"'

which will give you an output sa3tHJ3/KuYvI.

The second way (more simple) is to use command:

openssl passwd password_to_be_encrypted

Linux has an abundance of excellent terminal applications. Interestingly, I could not find any decent comparison of their text display performance. Since I use the command line a lot, I want text output that is as fast as possible. When you compile a large project, you don’t want the console output to be the limiting factor.

Read more…

viper@viper-laptop:~$ cat /tmp/test

pop
pop1
pop2

viper@viper-laptop:~$ cat /tmp/test1

1
2
3
4

viper@viper-laptop:~$ paste /tmp/test /tmp/test1

pop     1

pop1    2

pop2    3

        4