scripting fun

[Johnny Rosenberg]

2008/6/7, Cameron Hutchison <lists at xdna.net>:
>
> Bart Silverstrim <bsilver at chrononomicon.com> writes:
>
> >So to be clear, the script I'm now using is...
> >**********
> >#!/bin/bash
>
> >join -v2 \
> >   <(iptables -L INPUT -n | grep DROP | awk '{print $4}' | sort -u) \
> >   <(grep -i slurp /var/log/apache-perl/access.log |awk '{print $1}' |
> >sort -u) | \
> >egrep '^([[:digit:]]+[.]){3}[[:digit:]]+$' |\
> >while read ip; do
> >   iptables -A INPUT -s $ip -j DROP
> >done
> >***********
>
>
> One more refinement I can see - grep piped into awk is redundant most of
> the time.
>
> The command pipeline:
>
>   grep DROP | awk '{print $4}'
>
> can be replaced with
>   awk '/DROP/ {print $4}'
>
> The second one:
>   grep -i slurp .../access.log | awk '{print $1}'
> is a little trickier since awk does not have a non-verbose
> case-insensitive switch, so you have to do one of these:
>   awk '/[Ss][Ll][Uu][Rr][Pp]/ {print $1}' .../access.log
>   awk '/slurp/ {print $1}' IGNORECASE=1 .../access.log
>
> This thread seems to be a follow up to another thread. Which one? I would
like to know what this script does (I'm a beginner so I can't really figure
it out myself).

Thanks

J.R.
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