I tried to use node.js instead of scapy, dropping down to a C++ addon that we wrote in order to do ioctl calls and send raw packets.

We ended up keeping the addon for the ioctl calls, but the addon for sending raw packets didn't make it: we didn't want to reconstruct the javascript object versions of packets sniffed by node_pcap in order to send them on the raw socket (didn't want to make a small mistake and break the whole project for ourselves).

So we used scapy that part of the tethering project; worked well for us though it could have used more docs.