Howtos / Articles

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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Flush the DNS cache on Windows

Windows will cache DNS resolution results for a period of time. You may need to clear this cache if you need to make sure the DNS value is up to date. The command below can be used to flush the DNS cache on a Windows machine. This can he useful if you are changing entries in the hosts file and you need to clear out any cached DNS resolution queries. Clear the DNS cache on Windows: Open the command prompt.…

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Check the reverse dns hostname for a IP on Linux

This guide will step you through how to take an IP address, and find out what its reverse dns host name is. This is useful for checking mail server DNS setup, etc. The DNS system works two ways. It is used to convert host names to IP addresses, but it can also convert IP addresses to host names. Two handy programs to perform DNS queries on Linux are ‘dig’ and ‘host’. If either of these aren’t installed on your system,…

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