Centroid.EU Blog

1993 Berlin wall pictures

November 9th, 2009

Pics from 1993.

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A theoretical attack on WildcardDNS and the Internet

November 7th, 2009

This attack theorizes on an attack on caching recursing nameservers. Pretend someone runs wildcarddnsd and thus wildcards the entire spectrum of their domain (zone).

this.is.valid.domain.com
stupid.little.tricks.domain.com
what.dns.is.not.domain.com

These are all valid A replies if domain.com has an A record set. Only problem is that when someone uses up the entire 255 characters of a valid domain name then the other recursing nameserver theoretically stores all this in memory for at least the time to live. So if someone looks up:

abcdef...a.domain.com (255 characters)
defghi...b.domain.com (255 characters)

.. then there is an awful lot that is stored in RAM on a nameserver.

If a botnet looks up these long domain names they can cause economic damage by wasting many many many bytes on an aggregate of foreign nameservers. And the nameserver that does wildcardding will get the bandwidth bill for all those lookups, although there is many "root servers" that have unlimited bandwidth for 60 euros a month. It'll look like a DOS but it's not (yet it can lead to a DOS).

To save the Internet some pain I've implemented the -W flag on my wildcarddnsd's and to basically save my ass the bandwidth charges.

Something to read that put me up to the idea:

• What DNS is Not

PS: you don't need a botnet to do some damage. If you have a link that allows spoofing you can spoof into networks that don't have ingress spoofing filters on their routers and fake a question to DNS servers that would otherwise refuse to answer you. With the amount of bandwidth one can get 50/10 Mbps a considerable amount of damage can be done. So the protection against this is to have solid networks out there that don't allow spoofing of any kind.

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Upgrade (Hell)

November 6th, 2009

This week I purchased and installed 3 things. One, Windows 7 Home Premium edition. Two, VMware Workstation 7 and finally F-Secure 2010 Anti-Virus. I've never had an anti-virus program before so this was a first install for me.

I also downloaded Kubuntu 9.10 and installed it as my VMware host operating system. That was necessary because my old Redhat lacked some libraries that I needed for good sound support with the VMware Workstation.

So I had to move some OS's out of my active host team that I keep in the on state in VMware, in order to accomodate the 1 GB footprint of Windows 7. Windows 7 was a pain to install because vmware has crappy dvd support and using a sparse file for the dvd didn't work due to some copyright protection.

When I install Windows I compartment a superuser and a regular user. This way if there is a virus when I use windows, it can't write over system files and install a root-kit or whatever. I usually name the superuser admin. Only when installing Windows it asks to install a user and I didn't name it admin but "pjp" my usual acronym. So when I learned that I wanted to install "pjp" as a user with less privileges I had to rename the admin account. It left the home directory as "pjp" and gave my pjp user the directory of "pjp_2".

Activating the one year subscription for the anti-virus was pretty easy and I hope everything is protected now. I set it so that it scans files that I download through the web (real-time).

These were just some experiences I had with this years upgrade, I probably won't upgrade for at least another year unless something blows up badly.

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Random Hackepedia

November 6th, 2009

This weeks hackepedia article is Multicast. Enjoy.

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WildcardDNS bug fix

November 3rd, 2009

I fixed a bug in wildcarddnsd that caused zones to be 'lost'. Everyone who uses wildcarddnsd should upgrade to the latest version or tag "BETA_3". In the CVS log there is more detail on what went in since BETA_2.

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Playing with xearth

November 2nd, 2009

rosalind$ history
...
44      xearth -pos "fixed 49 0" -sunpos "-15 0" -noroot -nostars -grid -markerf
ile markerfile 
rosalind$ more markerfile
50.05 10.23 "pbug"

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Hackepedia back online

October 27th, 2009

Hackepedia is back online after about a month of downtime.

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New features at WildcardDNS

October 25th, 2009

Someone asked if round-robin'ing was possible in wildcarddnsd. The feature was there once so there was still stub-code but it didn't work. I cleaned that up today and it seems to work. It makes wildcarddnsd a bit slower because the zones have to be written after every lookup, but otherwise NS, A and AAAA records do a wildcard round-robin now.

It's not in the repo HEAD yet but if you check out the ROUNDROBIN branch the code is added on to BETA_2.

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Thanks OpenBSD

October 25th, 2009

Theo de Raadt added my name to the list of people who do donations on their donations page. The list is quite large by now, and I always wondered why I wasn't added before. It turns out that if your donations accumulate to a certain amount (100 dollars CA or so) they put your name on the list. This is nice, it's a nice self-endorsement and it shows my passion for OpenBSD.

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OpenBSD 4.6 released

October 19th, 2009

OpenBSD 4.6 was released yesterday. I'm gonna have fun with this.

I just made a 15 euro bank donation to OpenBSD (which is 23 canadian dollars). I'm doing this in lieu of buying the CD's, but I'm looking forward to perhaps getting 4.8 on CD next year.

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