Hi Everyone, I'm having trouble with a C application that opens a USB modem. The application is not receiving some data from a USR modem. Conexant modems are OK. I'm working through https://www.kernel.org/doc/Documentation/usb/usbmon.txt . I found the modem at Bus=01 Dev=24: T: Bus=01 Lev=03 Prnt=07 Port=00 Cnt=01 Dev#= 24 Spd=480 MxCh= 0 D: Ver= 2.00 Cls=02(comm.) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=0baf ProdID=0303 Rev= 2.00 S: Manufacturer=U.S.Robotics S: Product=USB Modem This is where my confusion lies. It is not clear to me how to determine which socket to use for step #3 in usbmon.txt. Step #3 says: # cat /sys/kernel/debug/usb/usbmon/3u > /tmp/1.mon.out How do I determine which socket to use for Bus=01 Dev=24? Thanks in advance.