I have two computers: both running CentOS 6.7, 64-bit, with kernel 2.6.32-573.12.1.el6.x86_64. One is a laptop with an 2 core Intel processor and the other is a desktop machine with a 4 core AMD processor. Both with selinux enabled. I have a USB serial port device (a RR-CirKits LCC-Buffer USB). On the desktop I am getting this error: sauron.deepsoft.com% sudo minicom Device /dev/ttyACM0 access failed: No such file or directory. sauron.deepsoft.com% dir -lZ /dev/ttyACM0 crw-rw----. root dialout system_u:object_r:tty_device_t:s0 /dev/ttyACM0 But it is working on the laptop! gollum.deepsoft.com% dir -lZ /dev/ttyACM1 crw-rw----. root dialout system_u:object_r:tty_device_t:s0 /dev/ttyACM1 Same kernel, same device (except it is showing up as ttyACM1 on the laptop). What is going on here? -- Robert Heller -- 978-544-6933 Deepwoods Software -- Custom Software Services http://www.deepsoft.com/ -- Linux Administration Services heller at deepsoft.com -- Webhosting Services