topic permissions issue on /dev/mdem in Operating System - Linux

permissions issue on /dev/mdem

Amit Dixit_2 — Mon, 16 May 2005 22:23:50 GMT

Hi,
I am running ubuntu linux, and configured linmodem on it.

I have configured another user in it and when I try to dial internet using the user login it generates error /dev/modem not found.

I then su - root and chmod 666 to /dev/modem and then I am able to dial using that login but when I restart my box the permissions are gone again.

Anybody any Ideas why permissions not there when i am rebooting.

Thanks,
Amit.

Re: permissions issue on /dev/mdem

Steven E. Protter — Mon, 16 May 2005 22:44:26 GMT

Ubuntu, the other dark Linux is a very secure linux.

Based on my limited experience on that flavor, one of the following is true.

* the driver /dev/modem is recreated every boot, similar to an hpux insf -e, which would remove the permissions.

* SELINUX or some other script is checking permissions of important files at boot time and returning them to a more secure state.

* Your system has an added sysadmin script intended to improve security that is doing this.

To fix it depends on how it happened. If its an add in script eliminate or modify it. If its a "feature" of the release then add your own admin script to make permissions 666 on /dev/modem and make it the last script that gets executed at run level 5 in the init sequence.

SEP

Re: permissions issue on /dev/mdem

Gopi Sekar — Tue, 17 May 2005 01:25:46 GMT

another method would be to put the user you are trying in to the same group as /dev/modem.

or set sticky bit permission for your internet dialing application which looks for /dev/modem

if you want to continue to use chmod 666 method then put this in /etc/rc.d/rc.local (i hope this file exists in ubuntu)

Regards,
Gopi

Re: permissions issue on /dev/mdem

Sergejs Svitnevs — Wed, 18 May 2005 05:34:34 GMT

/dev/modem is almost always a link and you do not need set any permissions on a link. You should find the device that /dev/modem points to and do chmod o+rw /dev/ttyXX (assuming /dev/modem points to /dev/ttyXX).

Regards,
Sergejs