Apple iOS 5, What does it change for me?

There are some really nice looking changes on the way for Apple mobile users lucky enough to have a device that can be upgraded to iOS 5. I thought I’d throw together a quick look at how this will change things on a practical level for me as I use an iPhone and an iPad for work and personal use.

Update: 2011-10-13. I’ve added some more details.
Continue reading “Apple iOS 5, What does it change for me?”

Monitoring a Broadband Router

Just been asked this question by an ex-colleague so I thought it would be good to do a write up.

How do I monitor my broadband router?

There are a number of measurements that you can do to see the health of your router.

External Monitoring

Firstly, you can measure whether the outside world can “see” your router. This does mean that you have to allow “pings” from the Internet which does slightly reduce your router security and so this feature is often turned off by default. I use some external services to monitor the availability of both my web sites and my router:

Each of these have both free and paid services. It is servermojo.com that I mainly use to ping my router.

Internal Monitoring

Secondly, you may be able to turn on something called SNMP (Simple Network Management Protocol) in your router. This is a standard that allows monitoring of all sorts of information regarding servers, routers, etc. You will need to give the router an IP address of a PC within your network that will receive the information.

There are a number of free tools that allow you to monitor SNMP To monitor from within your home network, you can use PRTG or the free version of Kiwi Syslog Server.

SNMP will allow you not only to see that the router is alive but whether it is connected to the outside world (the WAN port), what speed communications it is using, how long since the connection came alive and many other parameters.
The key parameters to measure are:

  • When the WAN connection went up and down
  • What the download speed is
  • The Signal to Noise Ratio (SNR)
  • The Attenuation

If you are having intermittent router problems, these tools will give you the kind of ammunition you need to take to your ISP to encourage them to take you seriously and get the fault resolved.

Flashing the BIOS from Linux (OpenSUSE 11.0)

I’ve been a bit quiet here recently because I’ve mainly been working with my business laptop currently running Windows 7. You can see more about this on my other blog – Much Ado about IT.

However, the power supply on that died recently so I’m back to my trusty desktop which runs OpenSUSE 11.0 24×7.

I managed to get hold of an upgraded CPU for this a while back but I’ve not really had an incentive to upgrade till now. The new CPU supports hardware virtualisation but I need to enable this in the BIOS. Of course, this machine (based on an ASUS A8N-SLI Deluxe motherboard) has an old BIOS that doesn’t allow me to turn on these features so I needed to upgrade to the latest (v1805).

But, I only run Windows under VirtualBox on this computer and I don’t have a floppy drive so updating a BIOS is no trivial matter!

After some Googling, here is the answer:

  1. Install the coreboot-utils package
  2. As root, at a command prompt, run “flashrom” to check that your chipset is supported for writing
  3. Extract the .bin file from the archive containing the updated BIOS image
  4. Make a backup of the existing BIOS with “flashrom -r backup-bios.bin”
  5. For the paranoid, try writing that backup back to the BIOS with “flashrom -wv backup-bios.bin” to ensure there are no errors. Reboot at this point for the really paranoid
  6. Now flash the new BIOS with a similar command to step 5
  7. Reboot and check that the new BIOS is OK

If you get an error from flashrom saying that the new BIOS is the wrong size, you may have had a problem unpacking the bin file from the archive as I did. Unpack the whole archive to a folder.

If flashrom doesn’t work for you, there are lots of other ways – I like using GRUB to boot from a floppy disk .img file – very “Linuxy”.

More on the GRUB bug (with mixed PATA and SATA drives)

I’ve mentioned this one a couple of times so I’ll give a bit more detail because it is a nightmare to solve if you don’t know what is going on.

If you have both a parallel ATA (PATA, this is the way most hard drives were connected on desktops and laptops until around 18 months ago) and a serial ATA (SATA) hard disk controller on your PC (as many do) and hard drives connected to both controllers, you are going to get hit by the GRUB PATA/SATA bug.

When you boot from a CD/DVD drive (generally connected to the PATA controller) to install Linux, GRUB will see your hard drives in a specific order. It lists them as (hd0,0) etc. and this numbering is mapped onto the actual devices (e.g. /dev/hda for PATA or /dev/sda for SATA) using a mapping file in the grub folder.

The problem is that when you re-boot from a hard drive rather than the removable drive, it is likely that the order of the drives will change and GRUB can’t currently handle this.

You have a couple of choices now. You could install openSUSE 10.3 which treats all drives as though they were SCSI (e.g. /dev/sda etc.), no problems there.

If you want to use another distro though (e.g. Ubuntu), try this:

After installation from CD/DVD, reboot without the CD/DVD and see if GRUB works. If it fails to find the boot loader, you can edit the grub menu manually from within GRUB itself, see the documentation for details. Now you can play with the default drive (the “root (hd0,0)” bit) until you find the right one. Hint: you can type “(hd” and press tab to get a valid list of drives and partitions.

Once you have found the correct drive to use you can now boot normally.

Next, find the location of the grub install files (should be in /boot/grub).

As root, edit the device.map file and reset the device map to how the devices look when you are NOT booted from a CD – you should be able to work this out from your currently mounted devices.

Alternatively, edit the GRUB menu.list file to correct the “root” statements to the correct drives.

Yes, it’s a mess and has been that way for at least two years. I first noticed it when Knoppix (the first of the really good live distros) stopped working on my desktop PC though I didn’t know what the problem was then.

Here are some links to more information:

While I’m at it, here are some quick instructions for rebuilding GRUB:

  1. sudo -i (or su)
  2. grub (runs grub shell)
  3. find /boot/grub/stage1 (if it doesnt work, try without /boot) => should return installation drive, e.g. (hdx,y)
  4. root (hdx,y)
  5. setup (hd0) (for installation on MBR of disk 0. Alt: (hdx,y) to install on boot partition, etc.)
  6. quit

On Ubuntu, try update-grub to rebuild grub menu and reinstall
On all distros, grub-install /dev/hdx