Perturg.org - Scott's Geek Stuff

Perlfunc: extract_ip()

Thu, 09 Oct 2008 09:38:28 -0700

Pull an IP address from a string of text.

Code:

sub extract_ip {
		        my $txt = shift();
		
		        # 4 octets surrounded by some word boundary
		        if ($txt =~ /\b((\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3}))\b/) {
		                if ($2 > 255 || $3 > 255 || $4 > 255 || $5 > 255) { return ''; }
		
		                return $1;
		        }
		
		        return '';
		}

Election 2008 Poll is online

Wed, 08 Oct 2008 15:55:48 -0700

You preferred Obama's statements 67% of the time
You preferred McCain's statements 33% of the time

Voting purely on the issues you should vote Obama

Who would you vote for if you voted on the issues?

Find out now!

Perlfun: in_array()

Wed, 27 Aug 2008 15:50:00 -0700

Code:

sub in_array {
		        my $item = shift();
		        my @list = @_;
		
		        foreach my $l(@list) {
		                #print "$l => $item\n";
		                if ($l == $item) { return $item; }
		        }
		
		        return 0;
		}

Slashdot on brute force password cracking

Tue, 19 Aug 2008 17:52:00 -0700

Do you have even a basic understanding of maths? There are 2^2048 possible 2048-bit keys. If you split it between 2 computers, each has to do 2^2047. If you split it between 256 (2^8) then each has to do 2^2040. Split it between 1024 (2^10)? Each is still doing 2^2038. Maybe you've got over four billion computers. In that case, you only need to do around 2^2006 on each one.

In case you still have no concept of how big this number is, there are estimated to be around 10^80 atoms in the universe, which is around 2^266. That means that each of your four billion computers is having try 2^1740 keys for every atom in the universe.

To put it another way: Let's assume each of your four billion computers is a few orders of magnitude faster than anything I know of and can try four billion keys a second, giving you a total of around 2^64 keys tried per second. This means you can do around 2^76 per day. At this rate (and don't forget that we are assuming that you have almost as many computers that are orders of magnitude faster than anything real as there are people in the world) it will take you 2^1972 days to do an exhaustive search (although on average it will only take you 2^1971 days to find the key). For those following at home, that's around 2^1962 years. For reference, the universe is approximately 13.7 billion years old, which is a shade under 2^34 years.

In summary, if every atom in the universe was a computer that ran orders of magnitude faster than anything we can build today, and it ran for the life of the universe to date, you would not be able to crack a single 2048-bit message. If, however, you have a quantum computer, then you might be able to. - TheRaven64

Perl: redirecting STDERR to STDOUT

Mon, 14 Jul 2008 19:17:00 -0700

I had occasion that I needed to redirect all STDERR output (die statements) to STDOUT. A webapp I wrote only looks at STDOUT, so this code causes STDERR to merge with STDOUT.

Code:

open(STDERR, ">&STDOUT");

Alternately you can also do it by reassigning the raw file handles:

Code:

*STDERR = *STDOUT;

You can get fancy and redirect all output to a log file:

Code:

open(LOG,">/tmp/foo.log");
		
		*STDERR = *LOG;
		*STDOUT = *LOG;

Detailed look at fonts

Fri, 04 Jul 2008 08:32:00 -0700

I had no idea font display was so detailed, and complicated. Maxim Shemanarev wrote an extremely detailed analysis of how modern computers display fonts on a screen. I found the section on moving fonts 1/10th of a pixel horizontally fascinating. Interesting read if you like fonts and typography.

Perl output buffering on files

Tue, 01 Jul 2008 14:36:00 -0700

To turn off output buffering in Perl you just do:

Code:

$| = 1;

To do it on an open filehandle (so the file gets written right away) you have to do:

Code:

open(LOG,">>$log");
		LOG->autoflush(1);

Piers Anthony - Xanth

Mon, 30 Jun 2008 13:57:00 -0700

Here is a borrowed list of Xanth books.

A Spell for Chameleon

The Source of Magic

Castle Roogna

Centaur Aisle

Ogre, Ogre

Night Mare

Dragon on a Pedastal

Crewel Lye

Golem in the Gears

Valey of the Vole

Heaven Cent

Man from Mundania

Isle of View

Quesiton Quest

Color of her Panties

Demons Don't Dream

Harpy Time

Geis of the Gargoyle

Roc and Hard Place

Yon Ill Wind

Faun and Games

Zombie Lover

Xone of Contention

Smell Foop

Up in a Heaval

Cube Route Tor

Currant Events

Pet Peeve

Stork Naked

Air Apparent

Two to the Fifth

Jumper Cable

Perlfunc: get_file_perm()

Thu, 26 Jun 2008 11:53:00 -0700

Quick function to get the permissions of a file with Perl.

Code:

sub get_file_perm {
			my $file = shift();
		
			# Permissions are the second element of stat
			my $mode = (stat($file))[2];
			my $perm = sprintf("%04o",$mode & 07777);
		
			return $perm;
		}

Bash reading a file line by line

Tue, 20 May 2008 13:56:00 -0700

Here are the directions borrowed from the BashFAQ.

Code:

cat /tmp/foo.txt | while read line; do echo $line; done;

Linux date manipulation

Mon, 12 May 2008 09:54:00 -0700

The date command in Linux is very powerful for converting dates and times. If you have a given time in another timezone, or even UTC, you can convert it to your local timezone with this command:

Code:

date -d '2008-05-13 14:00 UTC'

If you want to convert a given time into unixtime just use a date format:

Code:

date +%s -d '2008-05-13 14:00 UTC'

Free SSL Cert

Fri, 09 May 2008 14:23:00 -0700

I just got a free SSL certificate for this site from StartCom. They have limited browser support, but Firefox is in the list. Not perfect, but not bad for free.

Wii/Friend Codes

Fri, 09 May 2008 09:11:00 -0700

Wii code: 2166-1639-8425-8450
Mario Kart Friend code: 2191-8139-1611

ImageMagick borders and shadows

Mon, 21 Apr 2008 09:52:00 -0700

I borrowed this simple ImageMagick hack to make images have a small border and drop shadow.

Original:

Code:

convert foo.jpg -resize 200 -bordercolor white -border 1 -bordercolor black -border 1 -background black bar.jpg

Code:

convert foo.jpg -resize 200 -bordercolor white -border 1 -bordercolor black -border 1 \
		-background black \( +clone -shadow 80x1+1+1 \) +swap -background white -flatten bar.jpg

The drop shadow example needs a white background to look decent.

Save The Developers

Fri, 28 Mar 2008 12:16:00 -0700

My good buddy Dave just pointed out a cool site: SaveTheDevelopers.com. They have a cool little javascript script that detects if you're running IE6 (an old browser) and prompts you to upgrade to a newer and more current browser. The code is now live on most perturb.org pages.