Fix gateway mac detection on linux (#434)
Fix gateway mac detection on linux (#434)

unsigned ints cant be less than 0, and the sizeof(ptr) != sizeof(static array)
shakenetwork/zmap,shakenetwork/zmap,shakenetwork/zmap,willscott/zmap,zmap/zmap,willscott/zmap,zmap/zmap,shakenetwork/zmap,zmap/zmap,shakenetwork/zmap,willscott/zmap,willscott/zmap,willscott/zmap