Why do some people load the tcp module and some people don't ?

iptables -A INPUT -p tcp -m tcp --dport 80 -j ACCEPT
Then another one says:
iptables -A INPUT -p tcp --dport 80 -j ACCEPT

From what I have read -m stands for module, what are the advantages from using -m tcp ?
Thanks - The noob.

no advantage, it is loaded implicitly

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The TCP module is loaded automatically because protocol TCP is specified.

This section will describe the matches that are loaded implicitly. Implicit matches are implied, taken for granted, automatic. For example when we match on --protocol tcp without any further criteria. There are currently three types of implicit matches for three different protocols. These are TCP matches, UDP matches and ICMP matches. The TCP based matches contain a set of unique criteria that are available only for TCP packets. UDP based matches contain another set of criteria that are available only for UDP packets. And the same thing for ICMP packets. On the other hand, there can be explicit matches that are loaded explicitly. Explicit matches are not implied or automatic, you have to specify them specifically. For these you use the -m or --match option, which we will discuss in the next section.
http://www.faqs.org/docs/iptables/matches.html (6.4.2 Implicit matches)

1 members found this post helpful.

Thanks for the answers.