Re: security questions

[brian moore <bem@cmc.net>]

On Sat, Oct 28, 2000 at 08:36:47PM +0200, Robert Waldner wrote:
> On Sat, 28 Oct 2000 10:06:56 PDT, Peter Jay Salzman writes:
> >also, i noticed that some accounts which are disabled are given a shell of
> >/bin/false:
> >
> >	ftp:x:100:65534::/home/ftp:/bin/false
> >
> >tiger seemed to hate this too.  i tried playing around with /bin/false.
> >can't seem to figure out what it is.  whatever it is, it's tiny.  only 4 kb
> >long.
> 
> 
> there are /bin/true (which gives a return code of 0 when run) and /bin/
>  false (which returns 1) (both values IIRC). very handy if you want to 
>  do something like `if (<bla> || /bin/true)` for some reason.
> giving a shell with /bin/false effectively disables the account´s
>  possibility to get a login shell, but (as in case with ftp) shouldn´t
>  hinder other services (eg ftp, pop3, .forward etc.).
> 
> all of the above is in theory, because I tried that some time 
>  ago but couldn´t get an ftp-login when the shell was /bin/false, but I 
>  remember reading about it somewhere...

typically, ftpd checks to see if your shell is in /etc/shells -- if it's
not, you can't ftp.

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