+/* default window/packet sizes for tcp/x11-fwd-channel */
+#define CHAN_SES_WINDOW_DEFAULT (32*1024)
+#define CHAN_SES_PACKET_DEFAULT (CHAN_SES_WINDOW_DEFAULT/2)
+#define CHAN_TCP_WINDOW_DEFAULT (32*1024)
+#define CHAN_TCP_PACKET_DEFAULT (CHAN_TCP_WINDOW_DEFAULT/2)
+#define CHAN_X11_WINDOW_DEFAULT (4*1024)
+#define CHAN_X11_PACKET_DEFAULT (CHAN_X11_WINDOW_DEFAULT/2)
+
+/* possible input states */
+#define CHAN_INPUT_OPEN 0x01
+#define CHAN_INPUT_WAIT_DRAIN 0x02
+#define CHAN_INPUT_WAIT_OCLOSE 0x04
+#define CHAN_INPUT_CLOSED 0x08
+
+/* possible output states */
+#define CHAN_OUTPUT_OPEN 0x10
+#define CHAN_OUTPUT_WAIT_DRAIN 0x20
+#define CHAN_OUTPUT_WAIT_IEOF 0x40
+#define CHAN_OUTPUT_CLOSED 0x80
+
+#define CHAN_CLOSE_SENT 0x01
+#define CHAN_CLOSE_RCVD 0x02
+
+/* channel management */
+
+Channel *channel_lookup(int);
+Channel *channel_new(char *, int, int, int, int, int, int, int, char *, int);
+void channel_set_fds(int, int, int, int, int, int);
+void channel_free(Channel *);
+void channel_free_all(void);
+void channel_detach_all(void);
+void channel_stop_listening(void);
+
+void channel_send_open(int);
+void channel_request(int, char *, int);
+void channel_request_start(int, char *, int);
+void channel_register_callback(int, int mtype, channel_callback_fn *, void *);
+void channel_register_cleanup(int, channel_callback_fn *);
+void channel_register_filter(int, channel_filter_fn *);
+void channel_cancel_cleanup(int);
+int channel_close_fd(int *);
+
+/* protocol handler */
+
+void channel_input_channel_request(int, int, void *);
+void channel_input_close(int, int, void *);
+void channel_input_close_confirmation(int, int, void *);
+void channel_input_data(int, int, void *);
+void channel_input_extended_data(int, int, void *);
+void channel_input_ieof(int, int, void *);
+void channel_input_oclose(int, int, void *);
+void channel_input_open_confirmation(int, int, void *);
+void channel_input_open_failure(int, int, void *);
+void channel_input_port_open(int, int, void *);
+void channel_input_window_adjust(int, int, void *);
+
+/* file descriptor handling (read/write) */
+
+void channel_prepare_select(fd_set **, fd_set **, int *, int*, int);
+void channel_after_select(fd_set *, fd_set *);
+void channel_output_poll(void);
+
+int channel_not_very_much_buffered_data(void);
+void channel_close_all(void);
+void channel_free_all(void);
+int channel_still_open(void);
+char *channel_open_message(void);
+int channel_find_open(void);
+
+/* channel_tcpfwd.c */
+void channel_permit_all_opens(void);
+void channel_add_permitted_opens(char *, int);
+void channel_clear_permitted_opens(void);
+void channel_input_port_forward_request(int, int);
+int channel_connect_to(const char *, u_short);
+int channel_connect_by_listen_address(u_short);
+void channel_request_remote_forwarding(u_short, const char *, u_short);
+int channel_request_local_forwarding(u_short, const char *, u_short, int);