Re: How to limit it ?

[Russell Coker <russell@coker.com.au>]

On Mon, 15 Nov 1999, Grzegorz Pawel Szostak wrote:
>> > My next problem is how to hide other lines in /etc/passwd file and
>> > /etc/group ... One user should see only his own line.
>> > Any ideas ?
>> > 
>> 
>> What for ? 
>> There is no sensitive information in /etc/passwd if you have shadow
>> passwords.
>... but anybody can send message to anybody with simple shell script ...
>PPawel, there is a war ... only root should be able to send message to
>anybody (if he wants). There is a lot of spam around us :)

People with accounts on your system should not send spam.  If they do then
kill them.
If someone can run "ls" and get the right results then they can just write a
program like this:

int main()
{
for(int i  = 0; i < 65535; i++)
{
  struct passwd *pw = getpwuid(i);
  if(pw)
    printf("%s\n", pw->pw_name);
}
return 0;
}

Try it, it works.

If someone is determined you can't stop them that easily.  I doubt that you
could create a usable Linux system in which you could give me a shell account
and make it impossible for me to determine the account names of all other
users.

-- 
Electronic information tampers with your soul.