A 3rd option (which I am using now) is to make your 'kannel' user a member of the group of your /dev/ttyS0, so you can leave the permission of the device file as it is, and only kannel (not ordinary users) can access the device file.
Cheers.
Rene Kluwen wrote:
Without saying anything about whether Kannel, run by root, is secure or not: You can either choose that option
or
chmod ugo+rw /dev/ttyS0 so ordinary users can also use your modem.
Rene Kluwen Chimit
