A little script to send yubikey keys (or any input string) over network.

yubikey.sh

#!/bin/sh
# Port to send message to
PORT=9999
# IP address of destination machine
DESTIP="127.0.0.1"

# Use UDP
NETCAT_CMD="nc -w 1 -n -u $DESTIP $PORT"

# Use TCP
#NETCAT_CMD="nc -w 1 $DESTIP $PORT"

while (true)
do
	read KEY
	echo "Got key $KEY"
	echo $KEY | $NETCAT_CMD
done