Yes, it does, but this is what I'm trying to avoid.
I can run the program if I execute it as root.
What I want to do is to execute the program as a normal user.
How can I do this?
How must I configure the system (/dev/lp0, /dev/parport0, /dev/port,
/etc/group) to allow this program to access the parallel port? I want to do
this to reduce the security issues related to running a program as root.
On 9/21/06, Justin Piszcz <jpiszcz@lucidpixels.com> wrote:
The program you are running needs root permissions perhaps? chown
root:root program; chmod 4755 program ; ./program
Justin.
On Thu, 21 Sep 2006, Ed Young wrote:
> I'm trying to access the parallel port (/dev/lp0) from a non root
process.
>
> Basically I have a program that can only access the port if it runs as
root.
>
> Here's what happens when I run as root:
> root@falcon:~/src/k74-1.0# ./pprxtx all set
> root@falcon:~/src/k74-1.0# ./pprxtx read
> 255
> root@falcon:~/src/k74-1.0# ./pprxtx all clear
> root@falcon:~/src/k74-1.0# ./pprxtx read
> 0
>
> Here's what happens when I run as a non root user (ed):
> ed@falcon:~/src/k74-1.0$ ./pprxtx all set
> /dev/port: Permission denied
> ed@falcon:~/src/k74-1.0$ ./pprxtx read
> /dev/port: Permission denied
>
> /dev/lp0 I thought that all I had to do was to add my non rootport user
to
> the device group (lp) in /etc/group and then that user would have
> permissions to read and write to that device.
> lp:x:7:cupsys, ed
>
> I also changed the device permissions to
> /dev:
> crw-rw-rw- 1 root lp 6, 0 2006-09-21 04:56 lp0
>
> I still can't access the port unless I run as root.
>
> If I change the /dev/port (dangerously insecure) permissions to
> /dev:
> crw-rw-rw- 1 root kmem 1, 4 2006-09-21 04:56 port
>
> I then get:
> ed@falcon:~/src/k74-1.0$ ./pprxtx read
> /dev/port: Operation not permitted
> ed@falcon:~/src/k74-1.0$ ./pprxtx all set
> /dev/port: Operation not permitted
>
> Any ideas? I've done a fair amount of googling this and it seems like
I'm
> doing everything correctly.
>
> Thanks,
>
> --
> Ed
>
--
Ed