Category: Linux

  • FreeRADIUS two factor authentication (OTP and Password)

    MultiOTP is a tool to verify one-time passwords from hardware or software HOTP or TOTP devices. In the README they describe how to set up FreeRADIUS for OTP verification. By default, MultiOTP requires entering a 4 digit personal PIN plus the token (usually 6 digits). For better security in multi-factor authentication (MFA), it’s a good […]

  • Two-factor authentication for mySQL users

    I want to authenticate mySQL users with a password and a token on Ubuntu, so I figured out a way to do this using MariaDB, PAM and Google Authenticator. First we need a plugin for mySQL that can authenticate users against PAM. The non-free enterprise version of mySQL has I’m not an Enterprise customer, so […]

  • RAID5 array of 6 SSDs Performance Evaluation

    I’ve got six Crucial m4 SSDs with 256GB in a RAID5 array, resulting in 1.2TB useable disk space.The SSDs are connected via SATA3 to a Gigabyte 990FX UD7 board. I’m running 64bit Ubuntu 11.10 server. The following two articles offer some good ideas on performance tuning the SSD RAID: The chuck size on […]

  • Display all installed Ubuntu packages sorted by size

    dpkg-query -W -f’${Package}\t${Installed-Size}\t${Status}\n’ |\ awk ‘/installed$/ { print $2 “\t” $1 }’ |sort -n

  • WordPress 3.0.5 & Debian & blank screen when inserting objects

    When I try to insert an image into a blog post, all I get is a white blank page. The source code of that page reveals some javascript, and the FF error console reports “win.send_to_editor is not a function”. I’ve found countless postings on the web from other users who had this problem, none of […]

  • Reinstall all installed Ubuntu packages

    for pkg in `dpkg –get-selections | egrep -v deinstall | awk ‘{print $1}’` ; do apt-get -y install –reinstall $pkg ; done

  • fglrx in Ubuntu 10.10: disable underscan

    Do you see black borders on your TV when you connect your Linux HTPC with ATI Radeon chipset/card? Usually you would be able to change overscan/underscan settings in the graphical ATI tool – but my plasma is detected as a projector, some underscan is applied and the slider to correct it is missing. The solution […]

  • Disable automatic udev rules for network interfaces in Ubuntu

    If you want to deploy a Ubuntu image across different hosts, each time you boot it on a new machine, a new udev rule for its network card will be created. You will then end up with eth1, eth2, and so on. There are different ways to work around this problem. Here is a simple […]

  • Thunderbird IMAP TLS Bug

    Thunderbird seems to be a bit buggy connecting via IMAP/TLS to a Courier server. When Courier is set up to disallow non-TLS connections, it advertises STARTTLS and LOGINDISABLED. This is a challenge for the mail client to send the STARTTLS command before logging in. Thunderbird doesn’t do that: as soon as it sees LOGINDISABLED, it […]

  • Debian, make and kernel rebuild troubles

    Building the Linux kernel on my Debian/unstable machine recently caused some trouble: everytime I ran make, all files were (re-)compiled, not just the ones of modules I just added. The problem is related to the latest make version 3.81rc-1. Downgrading to 3.81beta4 solved this for me. It’s actually a bug in kbuild, but I can […]