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I am looking at an IP Table construct, what does the following mean :

:INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0]

thanks

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where did you get that output from? What command produced it? –  mulaz May 3 '12 at 1:39

1 Answer 1

It means that the default policy for those three chains is ACCEPT, so all packets (in, out, and forwarded through your system) are 'accepted' (go through), and not firewalled (rejected or dropped).

Depending on the place where you got that, it might mean your current policy, or the default 'empty' policy for your system.

more info here

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Thanks Mulaz - so it negates the need to explicitly put the ACCEPT construct - smart...Is there a smart tool that allows you to dump in IP table firewall config and it will explain it in plain english ? I need to do some firewall rule analysis... –  thugzclub May 3 '12 at 1:50
    
It depends on the setup. If you want blacklisting (allow all, deny just some IP's/connections), you leave the policy to ACCEPT, and add rules to block (iptables -A INPUT -s some.bad.ip.addr -j DROP) –  mulaz May 3 '12 at 1:51
    
If you want whitelisting (more secure, so "better"), you alow some IP's (iptables -A INPUT -s some.good.ip.addr -j ACCEPT), and then change the default policy to DROP (iptables -P INPUT DROP) –  mulaz May 3 '12 at 1:52
    
basically, you put a bunch of accept/drop/reject rules, and if the packet doesn't match any of them the default policy is applied (in your example, the packet is accepted). Sorry, for another comment, not enough coffee for a time like this –  mulaz May 3 '12 at 2:02

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