HOw to use -m (match) in iptables

Question

i want to know what is the difference between these two commands

iptables -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT

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iptables -A INPUT -p tcp --dport 80 -j ACCEPT

Ignacio Vazquez-Abrams · Answer 1 · 2010-08-26 06:14:33Z

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Nothing, since the tcp match is implicit when filtering the tcp protocol.

answered Aug 26 '10 at 6:14

	SO IT MEANS -m option is only important for STATE matches , otherwise no need to use for tcp , udp , icmp – John Aug 26 '10 at 6:23
	If either no options imply a match or if an option implies multiple matches then you need to specify a match. Otherwise, `iptables` will figure out what you mean in the command line. – Ignacio Vazquez-Abrams Aug 26 '10 at 6:43

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