Virtually...

So, my old 750MHz box which found a new lease of life with Linux may have just lost it again after installing VirtualBox on my main PC.

This allows the installation and execution of a Guest OS simultaneously with the Host OS.

Installation of a Linux Guest is easy. However, this only gives a screen resolution of 1024x800 for the Guest. To increase it, you need to update the Linux kernel and install VirtualBox Guest additions. Full instructions can be found here.

Also worth noting is that if you want to ssh into the Guest from the host, using NAT it is necessary to set up port forwarding (see VirtualBox User Manual section 6.3.1). Once this is done, it is necessary to ensure ssh is running on the Guest, and ssh in with the correct port, e.g. using Xming:

plink.exe -l user -p 2222 localhost

Finally, it is good to set up folder sharing so you can access all the files on the Host. This is explained in section 4.3 of the User Manual, and you just have to make sure that the user is in the vboxfs group using:

usermod -a -G vboxfs user

And that should give a full screen Guest OS with access to the Host directories wherever necessary without the overhead of maintaining either separate hardware, or a dual boot system. Brilliant!

Network Geography and Topology (Part 2)...

Setting up ICS wasn't so easy the second time, probably on the basis that I forgot to document some steps in the last post.

So, to do things properly, you have to set the router to IP address 192.168.2.x, so the wireless adapter on the Windows PC connects on an appropriate subnet.

Then, on the wireless internet connection, right click properties and enable ICS.

It is probably necessary to set the IP address of the wired adapter to 192.168.0.1, and on my Fedora installation, the Linux box sets itself up on 192.168.0.254.

From the Linux box, you should be able to ping the Windows box on 192.168.2.x, and a good check is to ping a website, the IP address of which can be obtained by pinging from the Windows PC (e.g. ping www.google.co.uk).

If that works, then you just need to set up the DNS addresses on the Linux box. These can be obtained from your ISP, or from the settings in the wireless router. And they are added to /etc/resolv.conf in the format "nameserver xxx.xxx.xxx.xxx", by adding DNS1=xxx.xxx.xxx.xxx to file /etc/sysconfig/network-scripts/ifcfg-eth0:1 (or whatever file as appropriate).

I'll probably struggle to do this a third time, so have to avoid rebuilding my machines...

Volcanic Ash…

At last, someone talking about volcanic ash and closing UK airspace who actually knows what they are talking about...!

Seems to be a right load of nutters commenting on it though. How about a new rule: people who think they know better than the experts don’t get to fly on professionally engineered commercial aircraft; they have to build their own instead…

Performance Issues...

So, after a Vista re-installation, a quick listen to the fan showed that the CPU was working overtime. Investigation with Windows Process Explorer showed that this was down to DPCs (Deferred Procedure Calls), but didn't show what was causing them.

Then I found this blog which very quickly identified the Intel 82562V Network Adapter as the cause. All you need to do is turn off all the Power saving and Wake-on-Lan settings in the Power Management tab of the Adapter properties.

Easy as that...!

FeedDemon

Am currently liking FeedDemon, but not the adverts it subjects you to (unless you pay £9.83 to get rid of them). So good to find out how to disable them for free.

I guess I should be using a more web based solution, but I'm old fashioned: I like downloading stuff to my computer. Should try and grow out of that I suppose...

Engineering Terrorists...

Some terrorists have studied engineering, ergo engineers are more likely to be terrorists...?

Completely ridiculous article from the Guardian Comments section, which seems increasingly full of laughable 'entertainment' as opposed to serious comment... sometimes commentators just do way too much thinking...

Network Geography and Topology...

So, it should be simple: just plug all PCs into the router/modem that is connected to the internet, either with wires or wireless and full internet connectivity on all PCs.

But then geography comes into play. The router/modem is in the kitchen, the desktops are upstairs, and static cabling is simply not an option. So the problem is connecting an old 750MHz PC running Linux so that it can be accessed remotely (don't want an extra keyboard, mouse, video hanging around) to the upstairs desktop PC running MS Vista, without the expense of a wireless network adapter.

I tried adding a spare router and using the Vista PC as abridge, but it didn't seem to work and raised the average power consumption anyway. But an answer lies in a simple Ethernet crossover cable and Microsoft Internet Connection Sharing.

Setting up ICS is easy, although it sets up the PC as 192.168.0.1, so it may be necessary to change the IP address of the router/modem or Vista throws out a very unhelpful "can't do it 'cos I just can't!" errors.

Then the Linux network connector has to be set up. This is straightforward (delete the old one connection, and add a new one), although automatic IP address allocation using DHCP appears to be needed.

And that is it. Just need to try and set up the dreaded XDMCP ...!

Countdown...

There is a very strong possibility that by the end of the month I will be a dad. I've been preparing for it for nearly nine months (obviously), and very much looking forward to it. But it is still just a little bit scary...!

Design Patterns...

Looks like a good source of information here:

http://sourcemaking.com/

Will have to get round to reading it at some point...!

Routings...

So, image you have a happy wireless network which allows you to connect happily to the internet from your desktop machine.

But you also want to connect to a wired network which contains a Linux machine which won't connect to the wireless network for reason of not having a wireless adapter.

Easy you may thing, just connect the desktop to both networks and off you go. And it is that easy except that the connection from the Desktop to the internet via the wireless network is lost.

This is because the routing tables are set up to go through the wired network first, so the machine fails to find the internet (that is only my guess, but it certainly sounds plausible and the solution fits).

So, we just need to update the routing tables. These are displayed from an elevated command line with:

route print

And should show the active routes, with the network destination 0.0.0.0 as the two gateways. So all we have to do is to change the metric of the wireless network so it is less than that of the wired network with a command like:

route change 0.0.0.0 mask 0.0.0.0 192.168.1.1 metric 25 if 9

where if is the interface number of the wireless adapter from the Interface List, and metric is less than that of the wired adapter.

Easy...