Centroid.EU Blog

(this blog is mostly encrypted - adults only)

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Article in the BBC about IPv4 address exhaustion

May 11th, 2010

I think I've blogged about this before. The predicted date is September 9th, 2011 when all IPv4 addresses are given away. Here is the article. To quote the article...

Companies are being urged to get working with IPv6 now, to forestall any problems caused by the shortfall.


My new computer: conceived

May 10th, 2010

On january 27th, I blogged about my 24 year old history with computers. I have now decided on a new computer and it'll take a considerable chunk of my savings. The computer is going to be built with upgradeability in mind, so that 3, 5, 7 years down the road I can upgrade it to what is decent then. Basically I'll be getting an Intel Core i7-930 with 8 GB of RAM (2x4GB DDR3 modules) and a 160 GB Intel SSD , BluRay burner and a wicked socket 1366 motherboard. Also I'll get a semi-decent graphics card with 1 GB of RAM. The store I got an estimate on priced it all at 1625 Euros, and since I have to get some other things like speakers I'm counting on paying around 1700+ euros.

This computer by no means is a top-of the line, but it's powerful nontheless and I think I can call it my own personal supercomputer. ;-)


The non-latin character domain names

May 10th, 2010

This was all over the news a few days ago. Basically Egypt, Saudi Arabia and UAE now have the TLD (top level domain) in their language now. The DNS system basically piggybacks a code (really punycode) representation of the unicode for these domains. It's still in ASCII downbelow, take a look:

countrypunycode equivalent
Saudi Arabia.XN--MGBERP4A5D4AR
United Arab Emirates.XN--MGBAAM7A8H
source: IANA.ORG

So it's not a glitch in the sytem if you see something like domainname.xn--wgbh1c that's just egypt instead of it's previous domainname.eg.


Learning from Hackers

May 7th, 2010

I was once a system administrator. One system I administered was BSD/OS and it had a "gcc" group in /etc/group. The other administrators thought it was a good idea to restrict gcc to a set of people who asked to have gcc access. One guy didn't ask and he exploited the fact that the "ld" and "as" commands were not in the gcc group. He created an assembly file possibly with FreeBSD and then copied that over and assembled and linked the possibly very compatible assembly file. I thought the guy was brilliant and I want to show you rudamentally what he did, watch.

romeo$ uname -a
FreeBSD romeo.solarscale.de 7.2-RELEASE FreeBSD 7.2-RELEASE #1: 
Wed May  5 21:28:23 CEST 2010     pjp@romeo.solarscale.de:/usr/
src/sys/i386/compile/ROMEO  i386
romeo$ cat -n hello.c
     1  #include <stdio.h>
     3  int
     4  main(void)
     5  {
     6          printf("hello, world\n");
     7  }
romeo$ cc -S -o hello.s hello.c
juliet$ uname -a
NetBSD juliet.solarscale.de 5.0.1 NetBSD 5.0.1 (GENERIC) #0: 
Thu Jul 30 01:39:11 UTC 2009  builds@b8.netbsd.org:/home/bui
s/ab/netbsd-5-0-1-RELEASE/src/sys/arch/i386/compile/GENERIC i386
juliet$ as -o hello.o hello.s
juliet$ ld -static -o hello /usr/lib/crt0.o hello.o -lc
/usr/lib/crt0.o: In function `___start':
: undefined reference to `_fini'
/usr/lib/crt0.o: In function `___start':
: undefined reference to `_init'
juliet$ ld -static -o hello /usr/lib/crt?.o hello.o -lc
juliet$ ./hello
hello, world

Let that be a lesson to anyone. I sure learned from this guy.


Educating the me

April 30th, 2010

I've started attending a class for CSS (cascading style sheets). The main purpose is that I have a lot of HTML documents (including this blog) that could use a bit of style. I've already written a style sheet for this blog in a test environment and will be putting it up perhaps next week.


Random Hackepedia

April 30th, 2010

The RH for this week is Traceroute.

BTW if you're interested in contributing to hackepedia it now allows people to edit without logging in.


Playing with compression, fail.

April 25th, 2010

I made a small program that can compress a file on less space than gzip. It was fun writing it and under nominal conditions it performs very well. The reason this design didn't make it into our list of programs is because if the conditions aren't favourable and it hits an out of disk space problem then repairing itself is next to impossible. So it isn't used. But you can still study the failings of programs to understand why working programs work well.

Inside the program source code you'll see a typescript clip from the program working better than gzip, but add a bit more space in the sparsefiles in the filesystem it explodes badly.


Random Hackepedia

April 23rd, 2010

The RH for this week is Cryptsetup.


Changed graphics on website

April 18th, 2010

If you frequently come here to read this blog you may have noticed that the graphics changed. I spontaneously did this today and I like it. The main graphic is a triangle with a star (the sun) in its centroid all in the european colours. The star has nine points with three points to every side of the triangle. I made two pictures, one with a black background and one with a white background. The picture is supposed to represent the union between solarscale.de and centroid.eu which have been the same website under the two different names for a while now.


Airport Extreme JetDirect port has changed?

April 16th, 2010

I've been googling a bit now to find out why the port 9100 on my parents airport extreme didn't work for JetDirect printing. I've found this. Apparently the port changed on some firmware updates from 9100 to 9101. I'll give this a shot tomorrow when I visit, as Rendevous printing with an old 10.3.9 Mac Os X doesn't seem to work right on the setup that I got there.

Generally I'd portscan but nmap didn't compile on such an old version of Mac OS X.

Update: it's true it is on port 9101, although Mac OS X 10.3.9 doesn't have an option to configure the port right, I had to go into the cups webmanagement at localhost port 631 to make it work. Mac OS X 10.5.x (my dads macbook) worked with configuring the jetdirect port to 9101 in the apple config system.


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