If you go to Z’ha’dum, you will die!

Again and again I needed to find packages where the currently installed version is not from any of the currently configured sources (manually installed and forgotten, dropped from unstable). If those are newer than any of the available ones, there will be no prompt to update them, so they are a possible security risk.

The following aptitude search pattern finds them:

~i ?any-version(!~O.) !~U !~o

To enable the use of standard EUI-64 identifiers for IPv6 in windows:

netsh interface ipv6 set global randomizeidentifiers=disabled store=active netsh interface ipv6 set global randomizeidentifiers=disabled store=persistent

This makes the fixed IPv6 address of a host predictable. It will still generate temporary addresses for outgoing connections (daily by default). To disable those, too:

Preparing a Transcend 8GB microSD card for OSMC on my Raspberry Pi 2, I used the following partition layout:

Device     Boot    Start      End  Sectors  Size Id Type /dev/sdc1       14688256 15661055   972800  475M  c W95 FAT32 (LBA) /dev/sdc2           8192 14688255 14680064    7G 83 Linux

I made the f2fs with the following parameters:

mkfs.f2fs -s 2 /dev/sdc2

And used those mount options:

On current Linux, if you want to run a command with low priority so it doesn’t bother your foreground tasks, you can use the SCHED_BATCH scheduling parameter with schedtool:

schedtool -B -n 20 -e $COMMAND

If you want to use a raw device instead of a disk image for Virtualbox, for instance an LVM volume or a partition, you can create a vmdk file that references the raw device:

In order to change the aspect ratio of an AVI video without reencoding it, you can use mencoder to set the aspect ratio as a hint to the player during playback. The hint is unfortunately used by mplayer only:

In order to use a serial port as system console on Debian Linux, the following steps are required:

The kernel must be configured to use a serial console, for GRUB 2 this is done in /etc/default/grub:

GRUB_CMDLINE_LINUX="console=ttyS0,38400n8"

The bootloader must be configured to use a serial console for its own user interaction. Again, for GRUB 2 this is done in /etc/default/grub:

GRUB_TERMINAL="serial console" GRUB_SERIAL_COMMAND="serial --unit=0 --speed=38400"

Finally, you need a login getty on the serial line, so add to /etc/inittab:

T0:23:respawn:/sbin/getty -L ttyS0 38400 vt100

Show connection tracking table for Linux-NAT (iptables):

conntrack -L

dd bs=1M if=/dev/zero | openssl enc -rc4 \ -K $(dd bs=1 count=16 if=/dev/random | hexdump -e '8/4 "%08x"') \ -iv 00 -bufsize 65536 | (dd bs=1 count=65536 of=/dev/null && sudo dd ibs=65536 obs=1M of=/dev/sdX)

This overwrites sdX with an RC4 stream.

It is significantly faster than using /dev/urandom (on Linux), and uses less entropy, while usually serving the same purpose (for instance, to initialize a block device for use with a crypto layer).