+pid_t fork_and_close(void);
+ssize_t sendtofrom(int s, void const *buf, size_t len, int flags,
+ struct sockaddr const *to, socklen_t tolen, struct in_addr const *from);
+
+ssize_t recvfromto(int s, void *buf, size_t len, int flags,
+ struct sockaddr *from, socklen_t *fromlen, struct in_addr *toaddr);