Comment by fellerts

5 hours ago

I think this package does exactly what you need: https://pkg.go.dev/github.com/google/gopacket/routing. Works on my machine (error handling left to the reader)

    router, _ := routing.New()
    iface, _, _, _ := router.Route(net.ParseIP("8.8.8.8"))
    fmt.Println(iface.Name)

this prints my Ethernet interface as expected. It doesn't make any requests, it just figures out where to route a packet. I guess it interfaces with the OS routing table.

2 comments

fellerts

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rvermeulen98  4 hours ago

Thanks for sharing! This is definitely something I will look into, I am all in favor to simplify the current implementation of finding the "default" OS network interface.

  • contingencies  2 hours ago

    You'd better use the default route and not some random IP, particularly DNS IPs which people often meddle with.

      # IPv4 default route only
  uname
  Darwin$ route -n get 0.0.0.0 | grep interface | cut -d ':' -f2
  Linux$ route -nv  |grep ^0.0.0.0 | awk '{print $NF}'