> Many such modems present as USB serial devices, eg ttyACM or ttyUSB. > Consequently, modemmanager has the ability to open serial ports and > probe them to see if they respond to Hayes-style AT commands. That > functionality is currently triggered automatically by default, even > for USB serial ports whose USB device IDs are unknown to modemmanager, > or whose device IDs correspond to generic USB-to-serial adapters. > > I.e., if one is running a normal Debian installation and plugs in a > usb-to-serial converter, modemmanager will open the device and send AT > commands to it, to see if it is a modem. > > This behaviour is IMO unaccaptable, as a default. >
A clarification here, ModemManager doesn't automatically probe usb-to-serial converters, those are "greylisted" so that they're only probed on "manual scans". Of course, the vid:pid needs to be known to MM and in the greylist, for this to happen. ModemManager also doesn't automatically probe platform TTYs, like physical RS232 ports in the host. -- Aleksander