Howtos / Articles

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…

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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…

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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.…

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Enable IP Forwarding on Ubuntu 13.04

This howto guide outlines the steps to enable IP forwarding on Ubuntu 13.04. This is required if you want your system to act as a router. Check the current setting: $ sysctl net.ipv4.ip_forward This should output a 0 or a 1 depending on if it is already enabled or not. eg: the following shows where ip forwarding is disabled $ sysctl net.ipv4.ip_forward net.ipv4.ip_forward = 0 Enable the kernel option for IP forwarding: $ sudo sysctl net.ipv4.ip_forward=1 eg: $ sudo sysctl…

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Reset Elastix Web Interface Admin Password

The commands in this article can be used to reset the admin password for the Elastix web interface. This requires that you can log into the server at the console, or via SSH. If you dont have the login details to log into the console, or ssh in, you will need to reset the root password. This requires that you boot up the Linux system in single user mode. Once you are logged in, or have booted into single user…

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