Howtos / Articles

Synchronize the time on Ubuntu from a NTP Server

To synchronize the time on a Ubuntu computer, with the time from a NTP server, you can simply run the following command: sudo ntpdate Replace “” with your NTP time server of choice. Example output: $ sudo ntpdate 1 Jul 00:50:12 ntpdate[31843]: adjust time server offset -0.001309 sec $ Your time will now be synchronized to the time from the NTP server. You can put this in a cron job to periodically update the time, to ensure…

Read more [...]

Change the Timezone in Ubuntu

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.…

Read more [...]

Generate new SSH keys

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 generate new SSH keys. With the increasing use of virtual servers nowadays, if you are creating new servers based on a image file/backup, you may…

Read more [...]

Prevent DNS Amplification Attacks with BIND

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 possible, so that more data is sent to the target IP address, flooding their connection. To help prevent these attacks, always make sure your DNS…

Read more [...]

Install the dig DNS lookup utility on CentOS

The dig DNS lookup utility is a handy tool for performing DNS queries. The dig utility is part of the bind utilities package in CentOS. The following command can be used to install dig. Install dig (the bind-utils package): # yum install bind-utils Note: Make sure you run the above command as a user with root privledges. You should now be able to use dig to perform DNS lookups. See ‘man dig’ for more information.…

Read more [...]

Page 2 of 2112345678910...20...Last »