+extern int recvfrom(int sockfd, void *buffer, size_t length, int flags, struct sockaddr *clientaddr, socklen_t *addrlen);
+extern int recv(int sockfd, void *buffer, size_t length, int flags);
+extern int sendto(int sockfd, const void *buffer, size_t length, int flags, const struct sockaddr *clientaddr, socklen_t addrlen);
+extern int send(int sockfd, void *buffer, size_t length, int flags);
+
+extern int setsockopt(int socket, int level, int option_name, const void *option_value, socklen_t option_len);
+extern int getsockopt(int socket, int level, int option_name, void *option_value, socklen_t *option_len);
+
+extern int getsockname(int socket, struct sockaddr *addr, socklen_t *addrlen);
+extern int getpeername(int socket, struct sockaddr *addr, socklen_t *addrlen);
+