Hide Apache Server Signature

To hide the detailed information about your Apache web server, OS and plugins, you disable the ServerSignature directive by modifying your Apache configuration file:

On CentOS
vi /etc/httpd/conf/httpd.conf

On Ubuntu
vi /etc/apache2/apache2.conf

Search for ServerSignature and change it to off
ServerSignature Off

Save the config and reload Apache to apply the change:

On CentOS
service httpd reload

On Ubuntu
/etc/init.d/apache2 reload

OSX Startup keys

Some useful startup keys for Mac:

  • C : Force boot from the CD-Rom drive
  • D : Force boot from the internal hard drive
  • Option : System picker show all bootable disks
  • Space Bar : Apple extension manager
  • Command-S : Boots Mac OS X into “Single User” mode
  • Command-V : Boots Mac OS X into “Verbose Mode”
  • Command-Option-P-R : Erases PRAM if held down immediately after startup tone
  • Command-Option-N-V : Erases NVRAM

More at MacOSX Things and OtherWorldComputing

Major fiber cut in KTM

Thursday evening’s brief fire on a pole was much more severe than I would have imagined. It severed dozens of fiber and other cables. It took the ISPs whole night plus the following day to fix the mess.

If you’ve noticed the way the cables are pulled across the city, it won’t take you much to realize that its very unsafe and not surprising that fires are more frequent.

Fibers, PSTN, ethernet, custom (ethernet+DC, ethernet+AC etc) and a mix of power lines run through the same poles and they run in parallel. On top of that, power cables and non-power cables are often just millimeter apart, sometimes even tangled with each other. Some broken power wires are loosely joined. Sometimes no tapes are used to insulate the joints.

Why is the cabling the way it is? Because most of the time cabling is done by unskilled, untrained people lacking any knowledge of electricity safety or codes. ISPs employ teams of pole climbers and ladder carryboys. Their engineers barely work on field or monitor their work. The cabling ends up being messy, loosely hanging above pedestrian’s head.

When khatey-children burn some fire below on the cold winter night, the cables catches it quickly. Or, when the dew settles on the dusts above the wire and gets to the loose joints, it causes short circuit and sparks a fire. There could be dozens of other possibilities.

Here’s some picture during the repairs. But notice the laying of cables. If you start looking outside your window while you drive across town, you’ll see more like these.

If the ISPs learn from this, they should really think about redoing the cabling. Its prime time to start practicing proper safety codes and practices.

ESXi IDE hack

Installing VMWare ESXi 3.5 on IDE drive

Full article is at: http://www.vm-help.com/esx/esx3i/ESXi_install_to_IDE_drive/ESXi_install_to_IDE_drive.php

The main point:

If you run fdisk -l, you should see your IDE drive listed.
2) After you have console access you will enter the command vi /usr/lib/vmware/installer/Core/TargetFilter.py (note that the path and filename are case-sensitive).
3) Scroll down in the document until you find the section “def IDEFilter(lun)”. You will be changing the text:

return interface.GetInterfaceType() == ScsiInterface.SCSI_IFACE_TYPE_IDE
to
return interface.GetInterfaceType() == ScsiInterface.SCSI_IFACE_TYPE_ISCSI

If you have not used vi before, move the cursor to the end of “TYPE_IDE” and the press the Insert key. The press backspace to delete IDE and type in ISCSI. Then press the ESC key, type in the command :wq and press Enter to save the file and exit.

4) You will now be back at the console. If you had stopped the installer at the screen show below, you can press ALT-F2 to return to the screen and press Enter to start the install, but it will still generate the error shown in the image above. You will need to press ALT-F1 and then type in install and press enter.
5) When you run the install command, it is important to note that the installer will switch you back to the ALT-F2 (DCUI) screen. Press ALT-F1 to return to the console again. You will see the below screen again with the prompt to press Enter to install. Do so and the install will proceed.

Make USB drive bootable

Many new systems lack cd/dvd drive. An external cd/dvd drive is not easy to carry around. In such cases, installing Ubuntu linux or VMware ESXi from a bootable USB may be the only choice. Once you have it on USB, its even easier than to carrying cd/dvd media. [toc]

BIOS support for USB boot

Most modern systems can boot off USB drives. The BIOS should properly recognize the USB drive and show it under boot options.

Some older systems can be tricky but they might boot off USB selecting “USB HDD” option.

Converting ISO image into bootable USB

Mount the ISO image and USB.
$ sudo mkdir /media/iso
$ sudo mount -o loop my-image.iso /media/iso

If the image is already on the cdrom, it is good too, just mount the cdrom.

Mount your USB drive. You’ll need a FAT32 partition on the usb. In this case it’s showing up as /dev/sdb1. It might be /dev/sdc1 or different letter in your case.

$ sudo mkdir /media/usb
$ sudo mount /dev/sdb1 /media/usb

Then copy the whole contents of the ISO image into the usb

$ sudo cp -r /media/iso/* /media/usb

Rename file isolinux.cfg to syslinux.cfg

$ mv /media/usb/isolinux.cfg /media/usb/syslinux.cfg

You might need to update the file as per your requirement. For VMWare ESXi 3.5, it worked without any update.

Make the USB bootable

Time to umount the image and usb drive.

$ sudo umount /media/iso
$ sudo umount /media/usb

Now, you’ll need syslinux package. If it’s not in your system, you’ll have to install it

$ sudo apt-get install syslinux
$ sudo syslinux -f /dev/sdb1

Try booting off the USB now. If it gives problem, you might need to fix the MBR

$ lilo -M /dev/sdb

Voila. You now have a bootable USB drive.