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Re: iptables rule to block when DNAT is used



On Tue, 08 Apr 2003 at 03:17:18PM -0700, Kevin Buhr wrote:
> 
> Also note that the mangle PREROUTING chain is run on all incoming
> packets before any other chain, so:
> 
>         iptables -t mangle -I PREROUTING -s badbox.evil -j DROP
> 
> should drop all packets from "badbox.evil" before any other rule is
> checked.  Do some testing before taking my word on it, though.

Just a quick security point.  A better policy is blocking everything and
explicitly allowing what you authorize.  All my tables and all my chains
in those tables have a default policy of DROP.

Regards,

-- 
Phil

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--
Excuse #2: Solar flares 



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