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Old 10-14-2014, 04:06 AM   #1
Registered: Apr 2014
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Basic iptables question

Hi, I'm mondering why people set both protocol and match in rules..


-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT

surely just

-A INPUT -p tcp --dport 22 -j ACCEPT

is sufficient as you've already said you're examining the tcp protocol so don't need to then also "match" it.

Or am I missing something?
Old 10-14-2014, 06:01 AM   #2
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It is as the manual says, use -m --match if you want to use extension module to test specific property (--dport 22 property for example with tcp module)

But in your example, tcp match is implicitly set with -p tcp, so you don't need to explicitly use -m tcp here
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Old 10-14-2014, 07:00 AM   #3
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Ah good, so it's not functionally needed there, it's just "good grammar".


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