Fastd is nice and small secure tunneling daemon. A bit like OpenVPN, if you wish, but geared toward small devices, simpler in its design and in some ways more generic.
There was a FreeBSD port, but it has been marked as broken. The fix, however, is very simple, if you accept to get rid of AES128 and instead use the SALSA stream cipher:
cmake -DWITH_CIPHER_AES128_CTR=FALSE CMakeLists.txt make make install
If you were trying to compile a Contiki application that targets an MSP430 platform (T-Mote Sky for example) on FreeBSD, you might have noticed that msp430-gcc was removed from the port tree and replaced by gcc-msp430-ti-toolchain. Contiki does not support this newer toolchain so you might find yourself a bit stuck there.
Fortunately you can still access the last version of the msp430-gcc packages from the FreeBSD archives: