Tag: Best Posts

Biba and BLP for Network Services

Michael Janke has written an interesting article about data flows in networks [1], he describes how data from the Internet should be considered to have low integrity (he refers to it as “untrusted”) and that as you get closer to the more important parts of the system it needs to be of higher integrity. It […]


SE Linux Policy Loading

One of the most significant tasks performed by a SE Linux system is loading the “policy“. The policy is the set of rules which determine what actions are permitted by each domain. When I first started using SE Linux (in 2001) the kernel knew where to find the policy file and would just read the […]


Review of the EeePC 701

I have just bought a EeePC 701 [1], I chose the old model because it’s significantly smaller than the 90x series and a bit lighter too and it had Linux pre-loaded. Also it was going cheap, while I am not paying for it I give the same attention to saving my clients’ money as to […]


Pollution and Servers

There is a lot of interest in making organisations “green” nowadays. One issue is how to make the IT industry green. People are talking about buying “offsets” for CO2 production, but the concern is that some of the offset schemes are fraudulent. Of course the best thing to do is to minimise the use of […]


Is a GPG pass-phrase Useful?

Does a GPG pass-phrase provide a real benefit to the majority of users? It seems that there will be the following categories of attack which result in stealing the secret-key data: User-space compromise of account (EG exploiting a bug in a web browser or IRC client). System compromise (EG compromising a local account and exploiting […]


Label vs UUID vs Device

Someone asked on a mailing list about the issues related to whether to use a label, UUID, or device name for /etc/fstab. The first thing to consider is where the names come from. The UUID is assigned automatically by mkfs or mkswap, so you have to discover it after the filesystem or swap space has […]

Misc Computer

Shared Context and Blogging

One interesting aspect of the TED conference [1] is the fact that they only run one stream. There is one lecture hall with one presentation and everyone sees the same thing. This is considerably different to what seems to be the standard practice for Linux conferences (as implemented by LCA, OLS, and Linux Kongress) where […]


Kernel Security vs Uptime

For best system security you want to apply kernel security patches ASAP. For an attacker gaining root access to a machine is often a two step process, the first step is to exploit a weakness in a non-root daemon or take over a user account, the second step is to compromise the kernel to gain […]

Ha Security

Car vs Public Transport to Save Money

I’ve just been considering when it’s best to drive and when it’s best to take public transport to save money. My old car (1999 VW Passat) uses 12.8L/100km which at $1.65 per liter means 21.1 cents per km on fuel. A new set of tires costs $900 and assuming that they last 20,000km will cost […]


Letter Frequency in Account Names

It’s a common practice when hosting email or web space for large numbers of users to group the accounts by the first letter. This is due to performance problems on some filesystems with large directories and due to the fact that often a 16bit signed integer is used for the hard link count so that […]