Wednesday 5 December 2012

Fix for "packages cannot be authenticated" warning on Ubuntu

Sometimes when installing packages on Ubuntu Linux, you'll get a warning like this:

sudo apt-get install foo bar
    WARNING: The following packages cannot be authenticated!

    foo bar
Install these packages without verification [y/N]?

The fix is trivial...

Thursday 15 November 2012

VMware 9.0 on Linux: Closing ports 443 and 902

On a Linux host, VMware Workstation 9.0.1 has TCP ports 443 and 902 open by default, listening on all interfaces.  This creates a small but unnecessary potential attack surface.
Here's how to close those open TCP ports...

Friday 26 October 2012

Apple Airport Express is not limited to 10 users

Just wanted to counter the myth that the old-style Apple Airport Express is limited to 10 users.  I'm sure I've had more than that in the past.  Today I've had 16 devices connected to one of the older 801.11 B/G Airport Express units.

Friday 5 October 2012

SOLVED: Issues with 2012 Airport Express

Apple has updated their entry-level wireless access point, the Airport Express.  The new version is a nice little square white box, supporting simultaneous dual-band operation (2.4 GHz and 5 GHz frequencies) plus the new 802.11n (high speed) mode.

The first time I installed this device, using the default factory settings, there was a problem with backward compatibility for non-"n" wireless devices.   I found I had to disable "n" support in order for any non-"n" devices to be able to find the wireless network.   Even then, performance was slow: the device had trouble sustaining 1 Megabit of throughput.  Yet the 5 GHz channel worked fine.

In the end, this turned out to be due to a strong local interference source (probably some dodgy imported consumer gadget) that was interfering with channel 7.  Switching to channel 1 solved the problem.  I never did find out what was interfering with the middle channels.

Wednesday 19 September 2012

Thursday 6 September 2012

Ubuntu 12.04 LTS - quick notes

Generally very impressive.  Good clear fonts, quick response on my old Dell Latitude D620 laptop.

Just a few tweaks to make. I'll add to this page as I use it more...

Tuesday 4 September 2012

Fix for Time Machine after Mountain Lion upgrade

After upgrading from Lion to Mountain Lion on two machines, the Time Machine backup application announced that it couldn't find the Time Capsule backup - even though that volume could be mounted and inspected manually.  There's a simple fix...

Fix for Firefox not opening PDF's on Mac

On Mac Mountain Lion, Firefox 14.0 runs in 64-bit mode by default.  This breaks the latest Adobe PDF reader.  The fix is simple: make Firefox start in 32-bit mode...

Friday 3 August 2012

New arrival

My technical work ("geeking" as SWMBO calls it) may have to wait a while, as my first child Elena has just arrived.  Mother and baby doing well. Dad having trouble with the poppers on Elena's sleep suits.

Monday 16 July 2012

Formatting a USB stick for UNETBOOTIN

I spent ages trying to create a bootable USB stick with UNETBOOTIN for BackTrack.  Turns out that the trick is to format the USB stick correctly before you start...

Tuesday 22 May 2012

Fix for unwanted subtitles on Humax FreeSat HD recorder

The otherwise brilliant Humax FreeSat HD recorder - the FoxSat-HDR - sometimes starts displaying subtitles that can't be turned off with the Subtitle button on the remote control.  To turn off those annoying subtitles, press the OK button twice.  I have no idea why that works, but it does.

UPDATE: you might want to try pressing EXIT first (see comments below), as pressing "OK OK" sometimes advances you to the current time, if you're watching live TV in delayed mode - which is generally when the subtitles seem to appear for no obvious reason.

Thursday 19 April 2012

Cisco bug: object-group ACL fails after reboot

It seems that object-group definitions are ridiculously buggy in router ACL's on IOS 12.4(24)T2.  Here's a simple example from my Cisco 877 router config.

Thursday 15 March 2012

How to burn a big file to DVD

If you want to write a big (> 4 GB) file to DVD, you must use a burning program that allows you to choose UDF as the format...  Otherwise, the burn process will fail, and you will end up with a useless coaster!

Thursday 8 March 2012

Apple Airport Utility: UPDATED

Airport Utility v6.0 looks very shiny, but has lost lots of features since the old version.  It no longer supports IPV6, syslog, connection monitoring graphs, or WDS (extending a network wirelessly).  Happily there is an easy fix...

Monday 6 February 2012

FIXED: Ubuntu 11.10 hangs after upgrade from 11.04: "Waiting for network configuration" then black X screen

Here's a fix for this problem, which I saw after upgrading a VMware Fusion 4.1.1 machine from Ubuntu 11.04 to 11.10.

Wednesday 4 January 2012

Preparing a new Ubuntu VM Server

Here is my crib sheet on setting up a new Ubuntu server, including notes on enabling Virtualisation.  These notes include discussion of Kimsufi / OVH dedicated hosting, but the principles apply to all dedicated servers.  I use Kimsufi because they are the only dedicated hosting provider that I can afford for non-profit purposes...

Monday 2 January 2012

Multi-WAN + Multi-LAN + No-NAT routing with pfSense 2.0.1

This notes summarise how to run multiple No-NAT LAN and WAN connections using version 2.0.1 of pfSense (an excellent open-source routing/firewalling appliance operating system).   My setup didn't work out of the box initially, so I thought it was worth writing up a summary of the settings that are now working here.