The first thing we need to do is make sure each Yubkikey has CCID mode enabled. This can be quickly checked with lsusb:
$ lsusb -d 1050:
Bus 003 Device 010: ID 1050:0116 Yubico.com Yubikey NEO(-N) OTP+U2F+CCID
This key already has CCID enabled. In fact, most …