Category Archives: English

Stuff written in English

Making your own FreeBSD Subversion repository mirror

Not long ago it was announced that the FreeBSD ports tree will cease exporting its Subversion repository to CVS, and subsequently any use of CVSup for updating the ports tree will be discontinued by February 28th 2013.

FreeBSD’s main source tree repository has been served by Subversion since late May 2008 with every commit done in the Subversion repository being exported to the old CVS repository, but no date has been announced when that Subversion to CVS transfer will be shut down. Stay tuned for more information.

Nonetheless, this is a Good Time™ to begin the transition from CVSup to Subversion once and for all. And why not set up your own FreeBSD Subversion repository mirror for both the main source tree and the ports tree well ahead of the transition? Continue reading Making your own FreeBSD Subversion repository mirror

How many IPv4 addresses are there?

An acquaintant posted the following question on an IRC channel earlier today:

How many IPv4 addresses are there?

The quick and simple answer is 232 = 4,294,967,296 addresses.

Is this an accurate answer? Yes, in a strict interpretation of the original question.

A far more interesting puzzle is if you want to account for all the IPv4 addresses usable on the public internet. Continue reading How many IPv4 addresses are there?

When to create a ZFS filesystem?

Someone named “Edward M” posted on the freebsd-questions mailing list a question of when should we create a ZFS filesystem. I didn’t reply to any of the messages, but I decided to write this post expressing my view.

In short, whenever a part of the filesystem hierarchy exhibits different characteristics, create one or more ZFS filesystems for that particular subtree. Continue reading When to create a ZFS filesystem?

Secret splitting

A few days ago I resurrected all my files from a desktop system I haven’t used for almost six years. Below is my implementation of secret splitting as described in Bruce Schneier’s book “Applied Cryptography, 2nd edition”.

The idea is basically: generate a random keystream, xor the plaintext with the random keystream, use separate couriers and send the random keystream and the ciphertext to the final destination using separate routes, and finally combine the random keystream with the ciphertext to recreate the plaintext. None of the couriers know which piece they are carrying.

To improve this idea would be to generate more than one random keystream, xor the keystreams and the plaintext, thus requiring more couriers and different routes for each datastream.

And, by the way, xor crypto isn’t really that strong. Continue reading Secret splitting