As preparation for a restore test, I removed the master boot record (MBR) of a Linux system recently:

1# dd if=/dev/zero of=/dev/sda bs=512 count=1

This command fills the first 512 bytes (containing the partition table and bootloader) of the first hard drive (/dev/sda) with zeroes (/dev/zero).

The problem is when you …

Sometimes it happens that you lock out yourself from your Linux system. In the worst case, additional security concepts or conditions might hamper access to the system, for example:

• No root access
• System cannot be rebooted to reset the password in a chroot session
• No colleague with system access available

Recently I …

Since 2008 I have been using the free Linux distribution IPCop to implement a customized firewall/a router. Of course, DSL providers also equip their customers with routers, but back then I was missing a couple of functions. To name some of them:

• IPSec / OpenVPN
• NTP time server
• DMZ segmentation
• WLAN access point with …

With the new major version 8, GitLab was extended to include a continuous integration (CI) component that was developed as dedicated project until now. While it was necessary to utilize external solutions, such as Jenkins, previously, it it now possible to automatically compile and test managed projects easily.

But, …

While registering a client system with a FreeIPA server I recently stumbled upon the following error message:

1# ipa-client-install
2...
3User authorized to enroll computers: admin
4...
5Kerberos authentication failed
6kinit: Cannot read password while getting initial credentials

After wasting quite a lot of time with …

Koukaam NETIO power outlets offer a network interface that can be used for controlling the particular ports comfortably. It would be even nicer to monitor them with Nagios or Icinga. 2012 I created a provisional bash script for monitoring the ports and time synchronization over NTP.

This weekend I migrated the script …

While testing a web application that uses PHP PDO to establish a connection to a PostgreSQL database I stumbled upon the following error message:

1Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[08006] [7] FATAL: Ident authentication failed for user "user"' in xxx.php …

If you haven't used an Oracle database for some time you might stumble upon the issue I just had: all internal user accounts were locked and I also didn't know the passwords.

By default login information of internal users are invalid after 180 days.

The following accounts are important to me on my Oracle 11gR2 Database …