Ubuntu 9.04

Ubuntu 9.04 has just been released and I upgraded. But there were several hitches. I am noting those down in this post along with their workarounds:

1. IPV6 problem In the past IP addresses were 4 numbers separated by dots like this 123.123.123.123 Each of those numbers have to be below 255, with some numbers reserved for LAN addresses, etc. (E.g. 127.0.0.0 is a shortcut for a loop-back i.e. to the same device where the IP packets originate. So 127.0.0.0 for each computer is the same computer itself)

Because the population of Internet users are growing these IP addresses are not sufficient. So they invented IPV6 -- a new way of specifying the addresses. Don't ask me the details because I don't know...but I do know that they can handle a lot more addresses than IPV4 Most modern browsers support them. Operating systems support them. Routers support them, and most nodes along the way (E.g. DNS servers) on the Internet support them. But many website servers still do not support them. Also you will find certain DNS servers and some ancient routers not supporting them.

That leads to problems. So for the time being the best way out is to do two things:

a) Switch off IPV6 in Ubuntu. A hard thing to do if you are using Kernel 2.6.28-11-generic. I found out after several hours. In Kernel 2.6.28-11-generic everything is burnt in, so you need to recompile the Kernel keeping the support of IPV6 outside of it ... something that I did not want to do. Luckily for me, Kernel 2.6.27-11-generic was also available on my machine, so I commented out the reference to Kernel 2.6.28-11-generic in the Grub boot file
Then I wrote the following line in a file called bad_list (which in my case was non-existing, so it was a new file that I created) The location of that file is /etc/modprobe.d/ This is a system protected folder so you need to use sudo

sudo nano /etc/modprobe.d/bad_list

Inside that file, I wrote one line:

alias net-pf-10 off

On some sites, they recommend that you can also write these two lines in /etc/modprobe.d/blacklist.conf

blacklist net-pf-10
blacklist ipv6


b) Switch to the DNS servers provided by openDNS (www.opendns.org)

Without doing the above two, you will find that Opera 9.26 will not work

2. Intermittent hanging of Gnome
Gnome hangs every now and then, especially when the new Firefox (3.0x) quits. There are also several other points at which Gnome hangs. For e.g. changing the wireless settings (the points may differ for you) I don't know why this is happening. Possibly a display manager problem. Possibly a hardware. I'll keep you posted. The whole screen gets mangled and nothing works ...only the mouse moves around. I can't even quit the blessed system gracefully; and I have to power off the computer manually. Not a good thing to do because I can possibly fry the hard-disk that way. I later on learnt that there could be a key-board short cut : CTRL-ALT-BACKSPACE which I could use to restart the desktop manager. Unfortunately, they've disabled that shortcut key in this version of Ubuntu for some vague usability reason. This is what you are supposed to do if you want the hotkey back:

1. Open a terminal window
2. Give the following command
sudo apt-get install dontzap
3. The above will install a utility called dontzap (It is not installed by default)
4. Give the following command
dontzap --disable
5. Restart

Now for some reason the computer hangs, you can try CTRL-ALT-BACKSPACE and you will be able to start again (All work in that session will immediately lost... but still it is better than a fouled up hard-disk)