Hi all It seems my USB Modem, is detected as USB device ( from the /var/log/messages file ), but the device interface isn't created. Here are the config files in my FC4 machine: /etc/modprobe.conf: alias eth0 forcedeth alias scsi_hostadapter sata_nv alias snd-card-0 snd-intel8x0 options snd-card-0 index=0 options snd-intel8x0 index=0 remove snd-intel8x0 { /usr/sbin/alsactl store 0 >/dev/null 2>&1 || : ; }; /sbin/modprobe -r --ignore-remove snd-intel8x0 alias usb-controller ehci-hcd alias usb-controller1 ohci-hcd I wonder about the reliability of these both last lines. Here is the /var/log/messages content, relative to the USB detection: Nov 3 13:06:14 ortolo kernel: ehci_hcd 0000:00:02.1: EHCI Host Controller Nov 3 13:06:14 ortolo kernel: ehci_hcd 0000:00:02.1: debug port 1 Nov 3 13:06:14 ortolo kernel: ehci_hcd 0000:00:02.1: new USB bus registered, assigned bus number 1 Nov 3 13:06:14 ortolo kernel: ehci_hcd 0000:00:02.1: irq 11, io mem 0xfeb00000 Nov 3 13:06:14 ortolo kernel: ehci_hcd 0000:00:02.1: park 0 Nov 3 13:06:14 ortolo kernel: ehci_hcd 0000:00:02.1: USB 2.0 initialized, EHCI 1.00, driver 10 Dec 2004 Nov 3 13:06:14 ortolo kernel: hub 1-0:1.0: USB hub found Nov 3 13:06:14 ortolo kernel: hub 1-0:1.0: 10 ports detected Nov 3 13:06:14 ortolo kernel: ACPI: PCI Interrupt Link [LUBA] enabled at IRQ 3 Nov 3 13:06:14 ortolo kernel: PCI: setting IRQ 3 as level-triggered Nov 3 13:06:14 ortolo kernel: ACPI: PCI Interrupt 0000:00:02.0[A] -> Link [LUBA] -> GSI 3 (level, low) -> IRQ 3 Nov 3 13:06:14 ortolo kernel: ohci_hcd 0000:00:02.0: OHCI Host Controller Nov 3 13:06:14 ortolo kernel: ohci_hcd 0000:00:02.0: new USB bus registered, assigned bus number 2 Nov 3 13:06:14 ortolo kernel: ohci_hcd 0000:00:02.0: irq 3, io mem 0xd3004000 Nov 3 13:06:14 ortolo kernel: hub 2-0:1.0: USB hub found Nov 3 13:06:14 ortolo kernel: hub 2-0:1.0: 10 ports detected Nov 3 13:06:14 ortolo kernel: usb 2-9: new full speed USB device using ohci_hcd and address 2 Nov 3 13:06:14 ortolo kernel: ACPI: Power Button (FF) [PWRF] Nov 3 13:06:14 ortolo kernel: ibm_acpi: ec object not found Here is the udev rules file content in the /etc/udev/rules.dev/ directory, relative to the USB devices only: # There are a number of modifiers that are allowed to be used in some of the # fields. See the udev man page for a full description of them. # # default is OWNER="root" GROUP="root", MODE="0600" # # all block devices SUBSYSTEM=="block", GROUP="disk", MODE="0640" <...> # serial+dialup devices KERNEL=="ttyS*", GROUP="uucp", MODE="0660" KERNEL=="ippp*", MODE="0660" KERNEL=="isdn*", MODE="0660" KERNEL=="isdnctrl*", MODE="0660" KERNEL=="capi*", MODE="0660" KERNEL=="dcbri*", MODE="0660" KERNEL=="ircomm*", GROUP="uucp", MODE="0660" KERNEL=="ttyUSB*", GROUP="uucp", MODE="0660" KERNEL=="ttyACM*", GROUP="uucp", MODE="0660" KERNEL=="tts/[0-9]*", GROUP="uucp", MODE="0660" KERNEL=="tts/USB[0-9]*", GROUP="uucp", MODE="0660" <...> # input devices KERNEL=="input/*", MODE="0660" <...> # usb devices KERNEL=="usb/dabusb*", GROUP="usb", MODE="0660" KERNEL=="usb/mdc800*", GROUP="usb", MODE="0660" KERNEL=="usb/rio500", GROUP="usb", MODE="0660" <...> KERNEL=="lp[0-9]*", SYMLINK="par%n" BUS=="usb", KERNEL=="lp[0-9]*", NAME="usb/%k" ... And here is the /usr/share/doc/MAKEDEV-3.19/devices.txt content, relative to the USB devices only: 108 char Device independent PPP interface 0 = /dev/ppp Device independent PPP interface <...> 144 char Encapsulated PPP 0 = /dev/pppox0 First PPP over Ethernet ... 63 = /dev/pppox63 64th PPP over Ethernet This is primarily used for ADSL. The SST 5136-DN DeviceNet interface driver has been relocated to major 183 due to an unfortunate conflict. <...> 166 char ACM USB modems 0 = /dev/ttyACM0 First ACM modem 1 = /dev/ttyACM1 Second ACM modem ... 167 char ACM USB modems - alternate devices 0 = /dev/cuacm0 Callout device for ttyACM0 1 = /dev/cuacm1 Callout device for ttyACM1 ... <...> 180 char USB devices 0 = /dev/usb/lp0 First USB printer ... 15 = /dev/usb/lp15 16th USB printer 16= /dev/usb/mouse0 First USB mouse ... 31 = /dev/usb/mouse15 16th USB mouse 32= /dev/usb/ez0 First USB firmware loader ... 47= /dev/usb/ez15 16th USB firmware loader 48 = /dev/usb/scanner0 First USB scanner ... 63 = /dev/usb/scanner15 16th USB scanner 64= /dev/usb/rio500 Diamond Rio 500 65= /dev/usb/usblcd USBLCD Interface (info@xxxxxxxxx) 66= /dev/usb/cpad0 Synaptics cPad (mouse/LCD) 180 block USB block devices 0 = /dev/uba First USB block device 8 = /dev/ubb Second USB block device 16 = /dev/ubc Thrid USB block device ... <...> 188 char USB serial converters 0= /dev/ttyUSB0 First USB serial converter 1= /dev/ttyUSB1 Second USB serial converter ... 189 char USB serial converters - alternate devices 0= /dev/cuusb0 Callout device for ttyUSB0 1= /dev/cuusb1 Callout device for ttyUSB1 ... <...> 216 char USB BlueTooth devices 0 = /dev/ttyUB0 First USB BlueTooth device 1 = /dev/ttyUB1 Second USB BlueTooth device ... 217 char USB BlueTooth devices (alternate devices) 0 = /dev/cuub0 Callout device for ttyUB0 1 = /dev/cuub1 Callout device for ttyUB1 ... <...> /dev/modem should not be used for a modem which supports dialin as well as dialout, as it tends to cause lock file problems. If it exists, /dev/modem should point to the appropriate primary TTY device (the use of the alternate callout devices is deprecated). <...> Arbitration of serial ports is provided by the use of lock files with the names /var/lock/LCK..ttyX#. The contents of the lock file should be the PID of the locking process as an ASCII number. It is common practice to install links such as /dev/modem which point to serial ports. In order to ensure proper locking in the presence of these links, it is recommended that software chase symlinks and lock all possible names; additionally, it is recommended that a lock file be installed with the corresponding alternate device. In order to avoid deadlocks, it is recommended that the locks are acquired in the following order, and released in the reverse: 1. The symbolic link name, if any (/var/lock/LCK..modem) 2. The "tty" name (/var/lock/LCK..ttyS2) 3. The alternate device name (/var/lock/LCK..cua2) In the case of nested symbolic links, the lock files should be installed in the order the symlinks are resolved. Here is my Problem: The proper device to be used for this USB ACM compatible modem ( theoretically ACM compatible ), should be: dev/ttyACM0, from a previous advice I got on this list. But this device is not being created when the modem is switched. So my question is: What should I do, for my modem to be accessible as a device, from my computer ? Thank you very much for your help. Best regards. Jean Francois Ortolo