Mar 162013

So one thing you learn pretty quick once you move into the cloud, is that what you normally would do to stop bots, rogue traffic, hackers, etc doesn’t quit work…even at the packet level.  What I mean is this, you have a web server sitting behind an aws load balancer and its under attack.  You are running linux.  First thing you do is set up an iptables rule to drop connections from that ip address.  The problem is, iptables never sees that ip address.  Iptables can’t look into packets.  Instead, it sees the load balancer ip address.  The ip address of the user is hidden in the x-forward-for.  So first thing you need to do is enable x-forward-for logging in your web server.  I will use nginx as an example:

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