Centroid.EU Blog

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Random Hackepedia

July 3rd, 2010

The RH for this week is Password.

This seems fitting since I just changed my passwords myself.

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The Korean incident: tcpwrappers

July 3rd, 2010

I was checking my logs yesterday when I noticed that someone from an IP in Korea was trying to brute force my pop3 daemon. I noticed after they got about 6000 attempts in. So I looked at wrapping them with tcpwrappers. The pop3 daemon on the outside of solarscale.de is Dovecot and they by default don't have tcp wrappers support. But there is a patch. So I applied it and noticed that some hunks of the patch failed. Particularely near the configure scripts so I ended up editing config.h myself and added the define for tcp wrappers in it. Then I built it and noticed that it would bomb out in 2 spots, all it needed was an edit in the Makefile to add "-lwrap" in the LIBS= line. Then it built. When it was installed I noticed that my changes to /etc/hosts.{allow,deny} were not effective. So I did a bit of googling and read that Dovecot is chrooted. So it was just a matter of finding the chroot and putting its own hosts.deny in there. It worked. So now only a select number of hosts can use the pop3 service.

goldflipper% telnet solarscale.de 110
Trying 62.75.160.180...
Connected to solarscale.de.
Escape character is '^]'.
Connection closed by foreign host.

The patch is found here.

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Doing Docking@Home

June 29th, 2010

I was doing setiathome and einstein at home, but setiathome usually has no work to give and einstein at home always produced calculation errors with my boinc client. So now I've replaced einstein@home with Docking@home.

Docking@Home is a project which uses Internet-connected computers to perform scientific calculations that aid in the creation of new and improved medicines. The project aims to help cure diseases such as Human Immunodeficiency Virus (HIV).

When there is seti work one out of the two cpu threads work on it, and currently I have two threads working away at it (two is equivalent to one core).

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The Summer Triangle

June 28th, 2010

Yesterday we were blessed with clear skies and I took the opportunity to take photos of the summer triangle. Which consists of the stars Deneb, Vega (shown) and Altair at the vertices. We were lucky to get them all into one shot.

There is a large version found here.

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The Arecibo Message

June 27th, 2010

Given the chart in the article below then, here is the approximate path the Arecibo message is taking through our Galaxy. The Arecibo message was an attempt at seeing if making contact with another world was possible. Here is the wikipedia article on it.

As you can see the message will travel through a pretty big chunk of our Galaxy. It will probably have countless opportunities to be picked up. So far the message is probably 36 light years away from our planet. Also the message won't be travelling in a straight line either as einstein's theory tells us that even light (or radio waves) will bend with influence of gravity from stars. This graphic is just an approximation.

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The Milky Way Galaxy

June 26th, 2010

I came across this image on wikipedia...

I couldn't help but notice that the constellations were marked into it so that you have somewhat of an idea where the earth is (in relation to the sun) . If you've been reading this blog continuously you might have seen pictures of Orion which was in the southern sky around midnight in winter. Now it's summer and almost in the southern sky at 12 midnight is Sagittarius. So then we're looking at the galactic center when it's summer, from our arm of Orion-Cygnus. This is really cool IMO, so then we're going to look at Cygnus constellation in Autumn and back to Orion in winter again. The southern sky around the eliptic is a giant rotating window and it's fun to see the constellations. (The program xephem helped me a lot as well).

I'm going to try to give these abbreviations names for you:

Ori	Orion	December
Cma	Canis Major	January
Pup	Puppis	February
Vel	Vela	March
Cen	Centaurus	April
Nor	Norma	May
Sgr	Sagittarius	June
Aql	Aquila	July
Cyg	Cygnus	August
Cep	Cepheus	September
Cas	Cassiopea	October
Aur	Auriga	November

More abbreviations of constellations are here. I've added the names of the month when the constellation is best seen at mid night looking south.

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Random Hackepedia

June 18th, 2010

The RH for this week is Ohm's law.

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What does the future hold?

June 14th, 2010

I have 4 sourceforge projects. Natally, Wildcarddnsd, Cryologd and twh. What is the future for them? Well I've given it a bit of thought on my summer break and here is the rough outline of the coding that I want to do.

Natally does tunneling real well. And it's encrypted however what I'd like to see from it is that it does address management as well so that clients connecting to it can connect to each other through the tunnels. Also when IPv6 comes along on my VPS I'd like to do a NAT feature for IPv6 because the addresses given to my VPS are going to be finite and I want to make use of them with the tunnels somewhat.

Wildcarddnsd is growing. The next big change planned for it is going to be a recursive server that allows me to change all my nameserver settings in resolv.conf be changed to my wildcarddnsd servers. The complexity is quite high so this may drag on. In my planning I've included an ascii drawing in the code for the code execution flow on how I think it should be done.

cryologd has been doing pretty well. Other than a condition where it exited for no reason (I think I got that fixed) there is not too much that needs to be done. One thing that the crypto code needs is an HMAC at the end of each frame for authentication which gets rid of the password exchange which may make this code a bit more robust and fluent. Changes going into cryologd can also be ported to natally as that's where it originated.

twh has been considered for removal on sourceforge. I don't plan to do development on it anymore but having the code resource on how to do the Berkeley DB stuff for example may be a good thing to have. Wish I had the time for it.

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