Securely wipe a headless remote linux server

Solution 1:

I have successfully gotten all the way through rm -rf --no-preserve-root / without the system crashing first, and without anything being left on the drive.

Solution 2:

The CentOS installer (anaconda) that ships with the PXE images includes a VNC server, so you can alter your grub config to boot the CentOS installer, passing the answers to the pre-stage 2 installer questions on the grub line, reboot and then VNC to the installer.

Now, if my memory serves me correctly, from within that installer you should be able to drop to a shell, from which you can access and destroy the disk.

Copy the vmlinuz and initrd files from the PXE dir in the CentOS distro (http://mirror.centos.org/centos/5/os/i386/images/pxeboot/) to /boot and modify your grub config:

default 0
timeout 5
title CentOS
root (hd0,0)
kernel /boot/vmlinuz.cent.pxe vnc vncpassword=PASSWORD headless ip=IP netmask=255.255.255.0 gateway=GATEWAYIP dns=8.8.8.8 ksdevice=eth0 method=http://mirror.centos.org/centos/5/os/i386/ lang=en_US keymap=us
initrd /boot/initrd.img.cent.pxe

Incidentally, any decent hosting company should be prepared to destroy your disks for you.

Solution 3:

Before you destroy the OS you could remove anything sensitive and zerofill (using dd if=/dev/zero of=justabigfile).

And I believe most systems will survive a dd to a running system long enough to overwrite the entire disk. There is no way back if it doesn't, of course.