Iptables: differences using conntrack or state module

I'm still new to (Arch) Linux, and I am looking into iptables right now. I was looking at the wiki, where there is this rule:
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
And I see in the default file /etc/iptables/simple_firewall.rules (owned by iptables 1.4.12.1-2) a similar rule:
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
Now, looking in the man page for iptables, I'm not sure I see/understand the difference between those two modules, conntrack & state:
conntrack: This module, when combined with connection tracking, allows access to the connection tracking state for this packet/connection.
NEW meaning that the packet has started a new connection, or otherwise associated with a connection which has not seen packets in both directions, and
ESTABLISHED meaning that the packet is associated with a connection which has seen packets in both directions,
RELATED meaning that the packet is starting a new connection, but is associated with an existing connection, such as an FTP data transfer, or an ICMP error.
state: This module, when combined with connection tracking, allows access to the connection tracking state for this packet.
NEW meaning that the packet has started a new connection, or otherwise associated with a connection which has not seen packets in both directions, and
ESTABLISHED meaning that the packet is associated with a connection which has seen packets in both directions,
RELATED meaning that the packet is starting a new connection, but is associated with an existing connection, such as an FTP data transfer, or an ICMP error.
Descriptions of the states are exactly the same, and for the modules conntrack has a "packet/connection" where state only has "packet", but I'm not sure what the differences/implications are.
Right now, it seems to me that, in the example rule quoted above, both modules/rules would get the exact same result (the difference between the 2 modules being that conntrack allows a lot more than just using state, whereas module state obviously only uses state) -- would that be correct?
Assuming this is right, I should be safe "translating" the rules from the wiki to use the state module instead? (just because it seems module state is all I need, plus I use a custom kernet and conntrack requires a few more options to be enabled)
Also, in that case, would there be a reason why conntrack was used on the wiki? Or would it be maybe a good idea to use the state module instead? (AFAICS all rules always only uses --ctstate to filter by state, nothing else, so using module state should be enough/work the same)
Thanks for any help/information.

http://serverfault.com/questions/190978/firewall-questions-about-state-and-policy wrote:Technically the conntrack match supersedes - and so obsoletes - the state match. But practically the state match is not obsoleted in any way.

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21.01.2008 18:57:48 - 03.04.2008 13:16:47 difference use function module

21.01.2008 18:57:48 - 03.04.2008 13:16:47 difference use function module

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WIth Regards,Jaheer.

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Is it necessary to use the standard function modules always?

Hi All,
Suppose i can retrieve the BUSINEES PARTNER ID from the table BUT000 with the help of 'BP_GUID' field through a select query statement.
Now is it necessary to use a standard function module to retrieve the same data. what about the performance? which is the better solution. to implement our own code or to use the function module available.
Please someone clarify me about this issue.
Regards,
Sharry.

If you'd ask the question in general it's obvious that there is no good answer as it always would depend on the circumstance. However, as you've posted your question in the performance tuning forum, let's look at your question in this context first. I think it's fairly safe to say, that in almost 100% of the cases a standard function module will not be as fast as any well implemented and custom tailored code. If in doubt, just try reading the code of the function module you want to read; most likely you will find lots of unnecessary fluff in there, often they read data that you don't even need.
And as far as buffering is concerned, that can also be an issue. E.g. let's say you do a massive read of distinct business partners and you only need the data once for each partner. Obviously buffering is silly in this case and it might even slow down your program, because the implemented buffering is not necessarily well implemented. I've come across a few cases, where the buffer tables where standard tables with no efficient read access (so no sorted table or hash table) and once tons of data were buffered, it actually took a moment to look up if the record already was buffered (just to find it wasn't there yet).
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Hello everybody!
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Hi :)
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This could work, but can you describe the use case for which you need to get the ApplicationModule?
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Sure, i know a lot of better ways to implement the same functionality too but its a huge project, its not my code and we have no time to reimplement this functions ;)
Frank, i don't understand the first line of your code.
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What is the difference between subroutine and function module?

What is the difference between subroutine and function module?

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Thanks,
Reward If Helpful.

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hi,
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Hi
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Using subroutines in Function Module

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Iptables: differences using conntrack or state module

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