Recently I bought a Soekris net6501 to build a home network in my new house. Things you need before you start: – USB / mSSD drive to install OpenBSD on – USB drive to boot from – Serial cable for the initial installation First go to a mirror and download the amd64 OpenBSD install image, […]
OSSEC is an Open Source Host-based Intrusion Detection System that performs log analysis, file integrity checking, policy monitoring, rootkit detection, real-time alerting and active response. It runs on most operating systems, including Linux, MacOS, Solaris, HP-UX, AIX and OpenBSD. There is no OSSEC package available on the OSSEC website or in the OpenBSDs ports repositry, […]
IMAP folders are really because you can have your e-mails synchronized on multiple devices, without losing e-mails across your devices when retrieving your new e-mails. IMAP folders actually also aren’t that cool because e-mails are usually never deleted or even archived. Having millions of e-mails can make some e-mail readers on certain devices really slow. […]
At my recent job, I was asked to create a backup procedure, which would dump a PostgreSQL schema to a compressed file and which was able to create weekly and daily backups. The backups had to be full backups each time a backup was made and the amount of daily and weekly backups should be […]
Update: This article is updated thanks to Colin Keith his excellent comment. I was extremely inspired by it Maintaining a large number of servers cannot be done without proper programming skills. Each good system administrator must therefor make sure he knows how to automate his daily works. Although many many programming languages exist, most persons […]
Not using indexes or huge tables without indexes, can have a very negative impact on the duration of a SQL query. The query planner will decide to make a sequence scan, which means that the query will go through the table sequentially to search for the required data. When this table is only 100 rows […]
Working on large database systems, with many tables and many indexes, it is easy to loose the overview on what is actually being used and what is just consuming unwanted disk space. If indexes are not closely monitored, they could end up using undesired space and moreover, they will consume unnecessary CPU cycles. Statistics about […]
Since the release of OpenSSH 6.2, two new configuration parameters have been added: AuthorizedKeysCommand AuthorizedKeysCommandUser These parameters allow to create any kind of authentication method for OpenSSH, including LDAP authentication, and therefore patches like the LPK patch for OpenSSH are not required anymore. The only thing the script needs to do is return either an […]
If you have a hosting account at Hetzner with free backup space, you can not access this backup volume using rsync. One way of creating a simple backup, is by using the tar command with the incremental option. You will also want to encrypt these backup files and one easy to do this, is by […]
Below is a small Perl example how to check for NFS mounted shares on a Linux host. The script does not need any specific modules, and makes use of the /etc/mtab file. #!/usr/bin/perl use strict; use warnings; my @mount_points = do {local @ARGV = ‘/etc/mtab’; }; foreach my $mnt (@mount_points){ next unless $mnt =~ /nfs/; […]