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user568948
Asked: 2020-04-10 08:04:48 +0800 CST

Block SYN,ACK response with iptables

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I have a virtual environment and Iam making a SYN flood attack to a Ubuntu Server's port 53 using Kali 2020.

I realized that a countermeasure for this attack is to limit or block the responses to the SYN packets, which are the SYN,ACK.

But how can I do this with iptables?

What else should be done to prevent that kind of attacks?

Any help would be appreciated.

iptables tcp syn flooding

1 Answers

  1. You'll want to DROP the SYN packet. But, I think you should revisit the TCP/IP 3-way handshake and reconsider your approach.

    Perhaps limit the rate of SYN packets to your DNS server or the rate of replies of anything other than just dropping all incoming connections (in which case, why not just shut the thing off?).

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