August 26, 2009
I’m often, at least more than I care, asked how to restore a Windows MBR/bootloader without having a windows install cd or a dos boot disk at hand. It’s quite easy you need just a Linux live cd like (the Ubuntu live cd or Knoppix) or an installed Linux you want get rid of. I really don’t know why you want to do the second, but anyway here are the 2 solutions I know of.
Boot Linux and make sure you’ve a working Internet connection and type following on the terminal/konsole.
sudo apt-get install syslinux
if the package got installed use following to write the MBR.
sudo dd if=/usr/lib/syslinux/mbr.bin of=/dev/sda
sudo apt-get install mbr
if the package got installed use following to write the MBR.
sudo install-mbr -i n -p D -t 0 /dev/sda
Common for both
Replace sda if you want to install the MBR to a different drive. Take a look at your hard disks with
sudo fdisk -l if you’re unsure. Finally reboot and your windows should boot.
It seems that Ubuntu not only Karmic (9.10), but also older versions have a problem with KVM (Keyboard, Video, Mouse) switches. To be exact the problem is the auto-detection of the capabilities of the monitor. If you connect the monitor directly to the computer everything works, if you use a KVM switch you get only 800×600 as the maximum resolution.
The workaround is to tell the xserver the Horizsync and Vertrefresh the monitor really supports. With older Ubuntu versions you could just add following lines (for a 1280×1024 LCD) to your
/etc/X11/xorg.conf in the monitor section:
Section "Monitor" ..... Option "DPMS" Horizsync 31.5-64.0 Vertrefresh 56.0 - 65.0 ..... EndSection
But starting with Karmic Ubuntu has no
/etc/X11/xorg.conf file by default anymore. So what we need is a complete minimal
xorg.conf file so we can include our 3 lines, but we don’t want to mess anything else up. This is the minimal config I came up with.
Section "InputDevice" Identifier "Generic Keyboard" Driver "kbd" Option "XkbRules" "xorg" Option "XkbModel" "pc105" Option "XkbLayout" "de" Option "XkbVariant" "nodeadkeys" EndSection Section "InputDevice" Identifier "Configured Mouse" Driver "mouse" EndSection Section "Device" Identifier "Configured Video Device" EndSection Section "Monitor" Identifier "Configured Monitor" Option "DPMS" Horizsync 31.5-64.0 Vertrefresh 56.0 - 65.0 EndSection Section "Screen" Identifier "Default Screen" Monitor "Configured Monitor" Device "Configured Video Device" SubSection "Display" Depth 24 Modes "1280x1024" "1024x768" EndSubSection EndSection Section "ServerLayout" Identifier "Default Layout" Screen "Default Screen" InputDevice "Generic Keyboard" InputDevice "Configured Mouse" EndSection
Except the Keyboard stuff the should be nothing thats not minimal. Maybe it is also possible to remove some lines there, but I didn’t test it. I was happy that it worked this way . If you’ve an even more minimal config write a comment please!
August 25, 2009
I just helped a friend whose server did not send cron mails to his mail server, which is this case led almost to data loss as the backup didn’t work correctly. I looked at the setup and I though I found the problem and correct it, but now I wanted to test it as easily as possible. Therefore I typed following command:
echo "Subject: test" | sendmail -v root
Then I looked if the lokal MTA, in this cache ssmtp delivered the mail to mail server. I though at least I find this line again if I search my blog and maybe it helps someone else too.
August 21, 2009
In the StartCom Blog the head of the company writes that its CA will be included by Microsoft. He states, “Starting approximately the 22nd of September, Microsoft intends to distribute a non-security update package to the Windows operating systems which includes the trusted StartCom root certificate and the automatic root certificate update service will update the cryptographic certificates root store on those systems whenever a StartCom issued certificate is encountered.”
Why is this worth reporting? This CA is with the above mentioned date the first CA which provides a Free SSL certificate which is supported by Microsoft and therefore by all Internet Explorer browsers. Sure this is “only” a SSL certificate which only assures the domain name or email address, but this is much more than now. You find many small mail servers where the webmail/IMAP/POP3/SMTP or a small homepage for a few users is self signed. All these can now be protected much better, the only problem seems to be that the CA is not supported by Firefox and other open source players. The other authority I know which provides free SSL certificates is CAcert. They are much stronger in the open source world, but with the inclusion of the StartSSL CA by Microsoft, they will have a much lower install base of browsers than StartSSL.
[Update] Mozilla and Apple support this CA for years already. My error – sorry. So these Free SSL certs are really something for a small website or mail server.[/Update]
August 18, 2009
Today my DNS registrar and in my case also the provider of the DNS servers for my domains had a total blackout. He was down for about an hour, none of the 3 DNS servers was reachable. Ok, this was bad, no system could get the IPs for domain names – nothing I can to there except using a 4th DNS server operated by me in the future. But this was not the biggest problem, some DNS servers had the IP for my mail servers stored and tried to connect via SMTP to my courier-mta. The problem now is that courier didn’t accept the connections it tried to lookup its own name via the DNS servers in
/etc/resolve.conf and ignored the settings in
/etc/hosts (basically its own name). I thought surely I’ve a configuration error until I found following in the courier-mta FAQ.
NOTE: The Courier mail server does not read the hosts file. It needs a DNS server (although it is possible to have a working the Courier mail server configuration in a completely DNS-free environment, this excersize requires changing many configuration files, and perhaps will be its own FAQ entry some day).
What the fuck? Courier stops working if the DNS server for the own domain/hostname is not reachable? That must be a bug and not a feature. I will talk to the author and report back what he says.
[update] I talked with the author and other courier experts. The way courier is written it uses one internal function to all his DNS stuff and as it needs MX,TXT queries it uses a glibc function in it with does ignore the hosts file. There is currently no way around it, and so I’ll need to deploy an DNS server on my mail server to provide a DNS which can always resolve it’s own hostname. [/update]