In that case, you can follow the instructions on the Wiki for using the demonstration backend on Croft. Kerklink will use a "packet forwarder" not developed by TTN. It forwards packets to the "croft" backend over UDP. Then you can fetch your data via MQTT:
To fetch data for your gateway (replace the gateway EUI with your gateway's EUI):mosquitto_sub -h croft.thethings.girovito.nl -t gateways/008000000000ABFF/status
To fetch data for your gateway (replace the device ID):mosquitto_sub -h croft.thethings.girovito.nl -t nodes/ABABCCED/packets
You can also put a + wildcard in place of the gateway/device ID, but then you get blasted with all packets from the network (and this will not scale as the network grows):
mosquitto_sub -h croft.thethings.girovito.nl -t nodes/+/packets
You can get the moquitto_sub program on Debian/Ubuntu with sudo apt-get install mosquitto_clients.
Hope that helps.