linktype is a link-layer header type code. The typical values are:
1 - Ethernet
191 - IEEE 802.15.4, with address fields padded, as is done by Linux drivers
195 - IEEE 802.15.4, exactly as it appears in the spec. FCS is expected to be present.
215 - IEEE 802.15.4, exactly as it appears in the spec, but with the PHY-level data for non-ASK PHYs (default)
230 - IEEE 802.15.4, exactly as it appears in the spec, and with no FCS at the end of the frame
The default value is 1.