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Re: analysis of auditable port scanning techniques
From: Dan Harkless <dan-bugtraq () DILVISH SPEED NET>
Date: Sat, 6 Jan 2001 02:43:57 -0800

Rainer Weikusat <weikusat () mail uni-mainz de> writes:
Dan Harkless <dan-bugtraq () DILVISH SPEED NET> writes:
Using this grammar applied to the data we send to an arbitrary host piped
to the ident/auth port will reveal the process owner running on a given
port, even though we initiated the connection.

Uh, no.  With properly-written ident daemons, such as pidentd,

if [ "$1" != sub ];
    export HOST=$(host $1 | awk '{ print $3; }')
    declare -i I=1
    export PPPID=$$

    while [ $I -lt 1024 ];
          export I
          socket -r -p "$0 sub" $HOST $I 2>/dev/null

        I=$(($I + 1))
   LOCAL=$(netstat -n | grep ":.\+$HOST:$I.\+EST"|awk '{print $4;}'| cut -d: -f2)
   echo "$I,$LOCAL" | nc -w 1 $HOST auth >/proc/$PPPID/fd/1
   kill $PPID

Just hacked up. Works wonderfully against pidentd 3.0.7-3 (Debian).

Thanks to those who corrected me on this.  I did test my understanding
before posting, and I couldn't get my pidentd to respond for connections
that didn't originate on its machine, but obviously I was doing something
wrong (not sure what).  A re-test just now reveals that indeed it will
respond correctly for connections not originating on the machine it's
running on.

Well, there's a feature request for auth/ident/tap daemons running on OSes
(if any) that can distinguish after-the-fact between connections that
originated locally and those that originated remotely.  Assuming that
doesn't break RFCs 931 / 1413, of course (I'd re-read them right now to
check, if I had the time)...

Dan Harkless                   | To prevent SPAM contamination, please
dan-bugtraq () dilvish speed net  | do not mention this private email
SpeedGate Communications, Inc. | address in Usenet posts.  Thank you.

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