How can I get file permissions to survive a reboot?

My modem is on device "/dev/ttyACM0". For my dailup program to work I have to set permissions on that device file appropriately. I have to login as root to do this. When I boot the computer the permissions are returned to original settings. How can I stop that? Ordinary users should be able to use dialup without having to log in as root.

I really want to use the "Gnome PPPD" program to manipulate the modem. This application is in the menu's of many distro's. Unfortunately it's busted however. It hasn't worked in years because it doesn't have permission to access files it needs. I've tried several distro's but they have the same problem. It never gets fixed. Apparently I'm the last person in the world using dialup on Linux.

Hi,

for device files this is set with udev (at least on most "current" linux distros). However, in your case you may do better to simply put the users in the dailout group. To confirm that this is a valid approach, please post the output of
*before* you modify it's permissions.

Also, you please tell us what distro you are using? The output of the following should provide this information:

Evo2.

The file permissions should not be changing
unless this is a "live" cd you are running
or a live image from a usb thumb drive ( mounting as read only)

YEARS ??? what operating system IS this ??? and how OLD is it

The OP states the file in question is /dev/foo. Files under /dev are created dynamically.
In the past by the MAKEDEV and devfs and more recently by udev. Therefore any changes made to the device ownership or permissions with chmod, chown etc, will be lost on reboot.

Evo2.