-int write_tun(int, char *, int);
-int read_tun(int, char *, int);
-int tun_setip(const char *);
-int tun_setmtu(const int);
+int write_tun(int, char *, size_t);
+ssize_t read_tun(int, char *, size_t);
+int tun_setip(const char *, const char *, int);
+int tun_setmtu(const unsigned);