Here I faced with a bit strange rule:

iptables -A INPUT -s -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 ( sends UDP packet it then receives TCP RST? This looks extremely strange..

1 Answer 1


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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