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red0ct
Asked: 2021-07-13 05:47:34 +0800 CST

Iptables --reject-with tcp-reset for non-TCP traffic

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Here I faced with a bit strange rule:

iptables -A INPUT -s 10.26.95.20 -j REJECT --reject-with tcp-reset

This rule matches all the protocols from specific network and rejects it with TCP RST packet.
How is this supposed to work with non-TCP packets? If other end (10.26.95.20) sends UDP packet it then receives TCP RST? This looks extremely strange..

firewall linux networking iptables tcp

1 Answers

  1. Best Answer

    Yeah, it makes no sense. IPTABLES also errors when I attempt to issue this on the command line (tested on CentoOS 8). It can only work if -p tcp is given which specifies that the rule is dealing with TCP traffic. Then it will work.

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