Archive | August, 2004

Fine-tunning SpamAssassin

by R.I. Pienaar on 31. Aug, 2004 in Usefull Things

Via RootPrompt I found a nice article titled Fine-Tuning SpamAssassin. It covers quite a bit of detail about SpamAssassin and is well worth a read.

Over time, however, many of the spammers have figured out how to fine tune their spam and bypass the default ruleset. I find the default setup still picks up at least half the spam, maybe two thirds on a good day, but too much leaks through. If the spammers are tuning their messages, I guess the only thing to do is to tune my scoring. There are at least 8 possible ways of improving SpamAssassin’s hit rate.
1. Blacklisting known offenders
2. DNS Blocklists
3. Enable Bayesian filtering
4. Reduce the point threshold for spam
5. Increase the scores on existing rulesets
6. Upgrade SpamAssassin to the latest version
7. Install more rulesets
8. Write your own rulesets

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Funfair

Funfair

by R.I. Pienaar on 30. Aug, 2004 in Photography

I have been looking for an opportunity to test out my new Nikon SB-800 Speedlight. The Funfair came to Blackheath again for the long weekend and this was the perfect opportunity to freeze some action on fast moving subjects.
The results of my outing can be seen in this collection of 8 photos, some cliche’d spinning wheels of color here and some nice shots of people having fun on the rides.


The SB-800 is a fantastic flash with full remote mode, can command a whole lot of other flashes and is very very powerful. It was designed for the D70, along with its smaller sister product the SB-600 it makes a very good addition to the D70.

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Simple Photo Browser

by R.I. Pienaar on 28. Aug, 2004 in Code

I have been using a bit of code I wrote for some of the small photo albums I uploaded here and decided I will polish it up a bit and make it available for download if anyone else is interested. This is not a big system for managing 100s of photos, it is designed to be ideal for showing up to 30 or so images in a nice clean manner.
You basically untar the distribution into the directory of your choice, copy your images into the img/ subdirectory. Create a list of files to display with something as simple as “cd img ; ls > list.txt” and add individual captions for photos by editing photo.jpg.txt. More info in the README file.
It supports themes and I think it is quite easy to create your own using the two provided in the tarball as a starting point. It can also work along with mod_rewrite to make nice looking URL’s but you can configure it to work without mod_rewrite as well.
Written in PHP and only needs your basic PHP, nothing fancy. Two samples exist of installations one using the provided black theme and one using the white theme both of these samples use mod_rewrite.
Version 1.0 is available for download: http://www.devco.net/code/spb/spb-1.0.tgz

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IPSec Simplified

by R.I. Pienaar on 24. Aug, 2004 in Usefull Things

I am again spending some time figuring out the workings of IPSec, this time I was interested in how to get it all going on PIX machines. While looking for information I came across 2 great articles about IPSec. They provide a simple introduction and were written by Dr. Peter J. Welcher.

IPsec phobia is caused by confusion. To cure that, we need some background information and terminology. Believe me, with a little orientation, this stuff makes a whole lot more sense! By the way, there’s lots of mathematics theory behind all this, but you won’t see it here. After all, you don’t need to know any of that to use IPsec.

It is split across 2 articles: IPSec Simplified and IPSec Simplified – Part 2.
The authors site has a large number of security and network related articles that seem of a very high quality and well worth checking out.

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SSL Certificate Authorities

by R.I. Pienaar on 24. Aug, 2004 in Usefull Things

Newsforge is running an article titled Be your own CA that covers the process for building your own CA as well as giving some background information on how it all sticks together, it is well worth a read if you are unsure how certificates, revocation and so forth works.
I usually use a guide and files found at http://sial.org/howto/openssl/ca/, it includes some make files to automate some of the work and to minimize user error, the two sites compliment each other nicely.

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Short visit to Zurich

Short visit to Zurich

by R.I. Pienaar on 22. Aug, 2004 in Photography

I went to Zurich for a few days this week, I have never been to Switzerland and Expedia had some good deals. I took a couple of photos of the city and people, mostly people, a collection of them can be found here. It is a small city with lots of little cramped roads and pavements that’s filled with tables and people eating. This style of architecture is very difficult to show on photos, so I focused mostly on the people.

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Calculating CIDR notation from IP ranges

by R.I. Pienaar on 13. Aug, 2004 in Code

Following from my previous post about blocking some more countries I discovered a bit of a short coming in the code I used to calculate CIDR notation from ranges of IP’s. So a bit of searching on CPAN got me Net::CIDR.

use Net::CIDR;
$range = shift;
print (join(“\n”, Net::CIDR::range2cidr(“$range”)) . “\n” );

This will take any given range of ip address in format a.b.c.d-w.x.y.z and spew out a list of subnets required to cover the whole range:

# ./range2cidr.pl 64.139.147.0-64.139.170.255
64.139.147.0/24
64.139.148.0/22
64.139.152.0/21
64.139.160.0/21
64.139.168.0/23
64.139.170.0/24

So with this I now have hopefully a more accurate set of rules that will not block bits of New Zeeland as well by accident.

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Taking Control Over Depth Of Field

by R.I. Pienaar on 13. Aug, 2004 in Uncategorized

Digital Outback Photo has a good article about Depth Of Field, well worth a read for anyone interested in moving from taking snapshots to taking photos that appeal on an artistic level.
It covers the basics of Depth of Field, how to achieve it using a camera and why in some cases it is very difficult, it then introduces the new Photoshop CS Lens Blur Filter that can simulate this effect where it was too difficult to achieve using the camera alone.

One of the skills that separates novice photographers from the more experienced is an awareness and control over “Depth of Field” (commonly referred to by its abbreviation “DOF”). Sometimes, to get the shot, we need to use a very small aperture. When we do, not only is the subject in sharp focus, but features in the background and/or foreground can compete for attention. This tutorial will walk you through the steps in using a new feature in Adobe Photoshop CS: the Lens Blur filter.

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Windows XP SP2 and WebDAV

by R.I. Pienaar on 11. Aug, 2004 in Front Page

A few of the guys in the office installed SP2 to start testing out and see what problems we will have from users. So far we discovered that where we could mount WebDAV folders on our FreeBSD Apache WebDAV server using the Map Network Drive dialog in explorer this now fails. It does not send the username in the HTTP request at all. Accessing it via File->Open and selecting “Open as Web Folder” using IE still works.
For now the work around we chose is to use Novell Netdrive, it seems like it is a free download and it allows you to mount WebDAV, FTP and Novell iDrive folders on your windows machine. It is much nicer than the mess of doing it through Map Network Drive and having to fiddle usernames etc.

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More country blocking

by R.I. Pienaar on 11. Aug, 2004 in Code

After blocking China and Korea recently I have still been getting quite a bit of scans and unfriendly traffic. Especially people who have been trying to log into my SSH servers with some simple user accounts like guest or by trying root logins. It’s purely automated and hit all my IP addresses. This comes from Japan mostly so I decided it is time to rid my world of the Japanese as well.
Problem was getting a good source for IP ranges. Turns out Maxmind publish their GeoIP Free Country database in CSV format as well, so then it was just a matter of writing up a tool to take their ranges of IP’s and create cidr notation entries and produce ipfw commands from those.
I got a bit of code from Gary Colman to do the translation from ranges to cidr notation and built that into my existing firewall builder script.

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