ttyUSB permissions after reboot

[Mirosław Siemczyk]

Dear All,

I start to use Fedora 16 with Sierra Wireless modems 3/4G (MC7710). Access
to modem is ttyUSB0-3, I assessed to AT comms by ttyUSB2 from normal user by
changing as a root chmod 666 /dev/ttyUSB* and it works , I can access by
e.g. putty etc..

My problem is that after re-boot chmod setting vanished and I have to
re-enter the same chmod comm as a root again. My question is what I should
do with ttyUSB to be able use access as a normal user after system re-boot?

Thank you in advance,

Miroslaw

[Christoph Wickert]

Am Donnerstag, den 29.03.2012, 12:02 +0200 schrieb Mirosław Siemczyk:
> Dear All,
>
> I start to use Fedora 16 with Sierra Wireless modems 3/4G (MC7710).
> Access to modem is ttyUSB0-3, I assessed to AT comms by ttyUSB2 from
> normal user by changing as a root chmod 666 /dev/ttyUSB* and it
> works , I can access by e.g. putty etc..
>
> My problem is that after re-boot chmod setting vanished and I have to
> re-enter the same chmod comm as a root again. My question is what I
> should do with ttyUSB to be able use access as a normal user after
> system re-boot?

What group are ttyUSB*? AFAIK they should belong to the group "dialout",
so you might want to add your user to that group.

If this does not help, you can add an udev rule. Create a file called
e.g. /etc/udev/rules.d/50-udev-default.rules

KERNEL=="ttyUSB*", MODE="0666"

As a last resort you can run chmod in /etc/rc.d/rc.local:

$ cat /etc/rc.d/rc.local
#!/bin/sh
chmod 666 /dev/ttyUSB*

$ chmod 755 /etc/rc.d/rc.local

But this really dirty and will only work on boot. You better want group
ownership or the udev rule.

Kind regards,
Christoph