/lib/udev/rules.d/40-ekeyd.rules is in ekeyd 1.1.5-6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | # Simtec Electronics UDEKEY01 Rules for udev
# Detect an Entropy Key being inserted
ACTION=="add|change", SUBSYSTEM=="tty", KERNEL=="ttyACM[0-9]*", ATTRS{idVendor}=="20df", ATTRS{idProduct}=="0001", IMPORT{program}="usb_id --export %p"
ACTION=="add|change", SUBSYSTEM=="tty", KERNEL=="ttyACM[0-9]*", ATTRS{idVendor}=="20df", ATTRS{idProduct}=="0001", IMPORT{program}="/bin/echo ENTROPY_KEY_SERIAL=$env{ID_SERIAL_SHORT}"
# Add the /dev/entropykey/FOO symbolic link
ACTION=="add|change", ENV{ENTROPY_KEY_SERIAL}!="", SYMLINK+="entropykey/$env{ENTROPY_KEY_SERIAL}"
# And tell the ekeyd about the new device.
ACTION=="add|change", ENV{ENTROPY_KEY_SERIAL}!="", RUN+="/lib/udev/entropykey.sh"
# And remove the entropy key from the daemon on device removal
ACTION=="remove", ENV{ENTROPY_KEY_SERIAL}!="", RUN+="/lib/udev/entropykey.sh"
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