contiki/tools/stm32w/uip6_bridge

See siscslow_ethernet.c for information about translation between
802.15.4 and 802.3 addresses.
Devices must have a proper EUI-64 address for this bridge to work.
If the EUI-64 address of the devices cannot be changed and they are
incompatible with the translation mechanism, you have to change the
translation rules (they are defined in mac_createSicslowpanLongAddr()
and mac_createEthernetAddr()).

Usage example:

run tapslip6 (source file are located in tools folder).

./tapslip6 -p 2001:db8:bbbb:abce::/64

where 2001:db8:bbbb:abce:: is the network address and 64 is the the
prefix length. The remaining 64 bits will be derived from the EUI-64 (two
middle bytes will be removed).

You can also simply create an edge router in one of the network nodes:
you have to enable routing and set the appropriate forwarding rules, as 
shown in contiki-init-net.c. Then you have to add the corresponding
rule on your machine, for example:
route -A inet6 add 2001:db8:bbbb:abcd::/64 gw 2001:db8:bbbb:abce:
	280:e102::8a.
	
where 2001:db8:bbbb:abce:280:e102::6c is the address of the edge
node and 2001:db8:bbbb:abcd::/64 is the lowpan address.