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Creating a SE Linux Chroot environment

Why use a Chroot environment?

A large part of the use of chroot environments is for the purpose of security, it used to be the only way of isolating a user from a section of the files on a server. In many of the cases where a chroot used to be used for security it […]

SE Linux status in Debian/Squeeze


I’ve updated my SE Linux repository for Squeeze to include a modified version of the ffmpeg packages without MMX support for the i386 architecture. When MMX support is enabled it uses assembler code which requires text relocations (see Ulrich Drepper’s documentation for the explanation of this [1]). This makes it possible to run programs […]

SE Linux audit2allow -R and Milter policy

Since the earliest days there has been a command named audit2allow that takes audit messages of operations that SE Linux denied and produces policy that will permit those operations. A lesser known option for this program is the “-R” option to use the interfaces from the Reference Policy (the newer version of the policy that […]

Tracking down Write/Execute mmap() calls with LD_PRELOAD

One of the access controls in SE Linux is for execmem – which is used to stop processes from creating memory regions that are writable and executable (as they make it easier to compromise programs and get them to execute supplied code). When the SE Linux audit log tells you that a program is attempting […]

Play Machine Online Again with Xen 4.0

My SE Linux Play Machine [1] has been offline for almost a month (it went offline late May 30 and has just gone online again). It’s the sort of downtime that can happen when you use Debian/Unstable.

For a while I’ve been using a HP E-PC (a SFF desktop system with 256M of RAM and […]

New SE Linux Policy for Squeeze

I have just uploaded refpolicy version 0.2.20100524-1 to Unstable. This policy is not well tested (a SE Linux policy package ending in “-1” is not something that tends to work well for all people) and in particular lacks testing for Desktop environments. But for servers it should work reasonably well.

I expect to have a […]

Can you run SE Linux on a Xen Guest?

I was asked “Can you run SELinux on a XEN guest without any problem?“. In a generic sense the answer is of course YES, Xen allows you to run Linux kernels with all the usual range of features and SE Linux isn’t a particularly difficult feature to enable. I do most of my SE Linux […]

Should Passwords Expire?

It’s widely regarded that passwords should be changed regularly. The Australian government declared last week the “National Cyber Security Awareness Week” [1] and has published a list of tips for online security which includes “Get a stronger password and change it at least twice a year“.

Can a Password be Semi-Public?

Generally I think of […]

Defense in Depth and Sudo

My blog post about logging in as root and whether sudo provides any benefit [1] got some interest on Redit. In the Reddit comments on my post [2] there are a lot of strange things. One interesting comment was to suggest that logging in as non-root provided “defense in depth”.

The NSA is credited with […]

Logging Shell Commands

In response to my previous post about logging in directly as root [1] it was suggested that using sudo is the only way to log the commands that are entered as root. One reason for doing this is if you don’t trust the people who are granted root access and you want to log all […]