If you compile RIOT for the native cpu and include the native_net module, you need to specify a network interface like this: ./bin/default-native.elf tap0 SETTING UP A TAP NETWORK ======================== There is a shellscript in RIOT/cpu/native called tapsetup.sh which you can use to create a network of tap interfaces. Usage: To create a bridge and two (or count at your option) tap interfaces: ./tapsetup.sh create [count] To delete the bridge and all tap interfaces: ./tapsetup.sh delete OSX === For tun/tap networking in OSX you will need: http://tuntaposx.sourceforge.net/ For OSX there is a seperate script called tapsetup-osx.sh. Usage is just like the other one.