Help to ensure that your server is secure from Open DNS Resolver expoitation

Recently, we notified customers regarding a network slowdown on the ServerSilo network. The Infrastructure Team quickly isolated the offending server resolved the issue. However we wanted to update all ServerSilo customers on the issue and explain how to prevent this from happening to your server.

What Happened
The server in question had benn configured as an "open DNS resolver," meaning that it allowed for third parties to bounce DNS requests off of the local DNS server and send responces on to another server for resolution. This is becoming a popular form of malicious activity.

Easily Preventable
All you have to do to protect your server from participating in this kind of attack is to ensure that your server doe snot allow DNS Recursion. This can can be easily accomplished from the command line or via most control panels (if you have installed one on your ServerSilo server). We have created a KB article with the instructions: http://support.serversilo.com/KB/a1858/how-to-disable-dns-recursion-on-your-dedicated-server.aspx 

Thank you again for choosing ServerSilo,

Ricardo Serenil
The ServerSilo Infrastructure Team
Published: April 23, 2013 at 9:30 AM

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