The Helpdesk For I.T. Administrators
The Domain Name System (DNS for short) is one of the most important parts of the internet infrastructure. It converts the easy to remember domain names, into IP (and IPv6) addresses, that aren’t so friendly to the end user. Regardless of the distribution of Linux that you are using (such as Ubuntu, CentOS, Debian, Arch, …
If you come across a server running OpenMediaVault, and you aren’t sure what the web GUI password is, give the following a try, as this is the default username and password for OpenMediaVault. Username: admin Password: openmediavault
When you need to access networks located on a different network segment, you need to have a route set up so the PC knows how to get to the other network segment. This generally just points to your main gateway, but you may want to set up additional static routes, where you don’t want the …
This guide will show you how to convert a .pfx certificate file into its separate public certificate and private key files. This can be useful if you want to export a certificate (in the pfx format) from a Windows server, and load it into Apache or Nginx for example, which requires a separate public certificate …
If you have a Ubuntu web server (running Ubuntu 14.04 LTS, 13.10, 12.04 LTS, or 10.04 LTS) set up using PHP FPM with Unix sockets, be warned that a recent security patch that fixes an issue with the PHP FPM socket permissions, may also break existing configurations, preventing your website from load php files. After …
The ‘sed’ command can be used to easily replace all occurrences of one string in a text file, with another string. For example: sed -i “s/wordtofind/replacewithword/g” /path/to/file.txt This command will find all occurrences of “wordtofind” and replace them on the fly with “replacewithword” in the file “/path/to/file.txt”. The “-i” command switch specifies to edit the …
To synchronize the time on a Ubuntu computer, with the time from a NTP server, you can simply run the following command: sudo ntpdate 0.pool.ntp.org Replace “0.pool.ntp.org” with your NTP time server of choice. Example output: $ sudo ntpdate 0.pool.ntp.org 1 Jul 00:50:12 ntpdate[31843]: adjust time server 12.34.56.78 offset -0.001309 sec $ Your time will …
To change the timezone on Ubuntu all you need to do is reconfigure the tzdata package. This can be done using the following command: sudo dpkg-reconfigure tzdata A menu prompt will then appear. Simply enter in your geographic area, and then the relevant city/timezone you want.
SSH allows the use of encryption keys to be used to allow logging into a system instead of having to remember a plain text password. This is great for use in scripts, and automated tasks, but can be a problem is anyone else ever gets the keys somehow. If the keys become compromised, you must …
DNS amplification attacks are a common form of DDoS that makes used of misconfigured DNS servers on the internet. The attack involves sending a request to the misconfigured DNS server, with a spoofed source IP address, so the response goes back to a third party (the target/victim). The attacker will use the largest DNS query …