Updated Firewall / Iptables Scripts

I have updated my iptables scripts today, mostly minor improvements and documentation updates in fw_laptop. I also added a new script called fw_blockall, which literally blocks everything (incoming, outgoing, and forwarded packets, packet from/to localhost, pings). This might be useful sometimes.

Any comments and suggestions for improvements are highly welcome!

The Underhanded C Contest

You thought that after the International Obfuscated C Code Contest, the Obfuscated Perl Contest, the International Obfuscated Ruby Code Contest and even the Obfuscated V contest nothing could surprise you anymore? Think again.

The goal of the annual Underhanded C Contest is to

write innocent-looking C code implementing malicious behavior. In many ways this is the exact opposite of the Obfuscated C Code Contest: in this contest you must write code that is as readable, clear, innocent and straightforward as possible, and yet it must fail to perform at its apparent function. To be more specific, it should do something subtly evil.

This year's challenge: covert fingerprinting. Write a program that performs some basic image-processing operation, but hides a unique fingerprint in the image it outputs.

The submission deadline is July 10th, 2005.

(via Bruce Schneier)

Summerschool Applied IT Security 2005

The RWTH Aachen is organizing a two-week Summerschool Applied IT Security. It takes place from September 19 to September 30 in Aachen, Germany.

There will be multiple lectures on a broad range of security topics as well as several hours per day where the students will be hacking and researching "offensive information warefare".

The course itself is free, but you have to pay and organize your hotel etc. yourself.

The FAQ, the homepage from last year's summerschool and the paper "An Offensive Approach to Teaching Information Security" (PDF) by the organizers provide more information.

I'd like to go, but I'm not sure whether I will find some hotel which is cheap enough for a poor student like me ;-) We'll see.

(via disLEXia 3000)

Write Down Your Passwords - The Right Way

Hm. Bruce Schneier and Microsoft's Jesper Johansson tell us to write down our passwords.

That may sound like a stupid idea, and many years lots of security-minded people tried to educate users not to do that. But I think they have a point. Someone who uses the Internet regularly accumulates a whole bunch of accounts and passwords for all sorts of sites, servers etc. It's simply too hard to remember all of them. Thus far I agree.

But, I don't think writing down passwords on small pieces of paper and carrying those around in your wallet is a particularly good idea. It happens too easy that you lose your wallet, it gets stolen, or you lose the pieces of paper. Not to mention all kinds of social engineering activities, which are simplified a lot by this approach...

I do propose to write your passwords down. But do it in a computer file on a box where you're the only one with an account (your home PC or laptop). Encrypt that file with GnuPG and your're reasonably safe. Every time you need a password, decrypt the file, read and use the password, then wipe the decrypted plain-text file.

No more pieces of paper - help save the environment.

My Firewall / Iptables Scripts

I have just uploaded fw_laptop, the firewall script I use to secure my laptop and/or desktop machines (but not my servers), in the Security section of my homepage. The script is GPL'ed and work in progress. I'm happy to receive feedback and/or corrections and suggestions regarding the script.

I will publish other similar scripts for different purposes when time permits.

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