Pb with inetd and ftp/tcp

[Jean-Michel Rouet <JM.Rouet@enst-bretagne.fr>]

I'm using a debian systems for 3 years or so with no problem at all. But
recently I discovered a rather stranger behavior with inetd and
particularly with ftp

Imagine that an evil person want to crash your machine sending a lot of 
non-authorized ftp requests like this (shell is zsh)

$ while `true`            
$ do
$   lftp -u foo,bar -e ls target-host &
$ done

after a few loops, the inetd daemon detects a problem and stops the ftp
server.
--> I found this message in the /var/log/daemon.log of the target-host
(in fact localhost :-))

Jun 19 14:34:52 joebar inetd[22750]: ftp/tcp server failing (looping),
service terminated


So as I understand it, anyone who has a tcp access to a machine can send a
huge amount of invalid ftp request and therefore crashes (or stops) the
ftp server !!! 

Is it a normal behavior ? 

JM 



--
Jean-Michel Rouet (thesard Dpt ITI) | Tel   : +33 298 001 057
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