diff --git a/include/libssh/sftp.h b/include/libssh/sftp.h
index f4dd6b74..767cff76 100644
--- a/include/libssh/sftp.h
+++ b/include/libssh/sftp.h
@@ -891,50 +891,6 @@ LIBSSH_API int sftp_server_init(sftp_session sftp);
  * @param sftp          The sftp session handle to free.
  */
 LIBSSH_API void sftp_server_free(sftp_session sftp);
-
-/**
- * @brief Decode the data from channel buffer into sftp read_packet.
- *
- * @param  sftp         The sftp session handle.
- *
- * @param  data         The pointer to the data buffer of channel.
- *
- * @return              Length of data decoded.
- */
-LIBSSH_API int sftp_decode_channel_data_to_packet(sftp_session sftp, void *data);
-
-/**
- * @brief Get the client message from a sftp packet.
- *
- * @param  sftp         The sftp session handle.
- *
- * @return              The pointer to the generated sftp client message.
- */
-LIBSSH_API sftp_client_message sftp_get_client_message_from_packet(sftp_session sftp);
-
-/**
- * @brief Handle the sftp_init request from client.
- *
- * @param  client_msg         The pointer to client message.
- *
- * @return                    0 on success, < 0 on error with ssh and sftp error set.
- *
- * @see sftp_get_error()
- */
-LIBSSH_API int sftp_process_init_packet(sftp_client_message client_msg);
-
-/**
- * @brief Handle the statvfs request, return information the mounted file system.
- *
- * @param  msg          The sftp client message.
- *
- * @param  st           The statvfs state of target file.
- *
- * @return              0 on success, < 0 on error with ssh and sftp error set.
- *
- * @see sftp_get_error()
- */
-LIBSSH_API int sftp_reply_statvfs(sftp_client_message msg, sftp_statvfs_t st);
 #endif  /* WITH_SERVER */
 
 /* sftpserver.c */
diff --git a/include/libssh/sftp_priv.h b/include/libssh/sftp_priv.h
index 005bf85f..54c90d85 100644
--- a/include/libssh/sftp_priv.h
+++ b/include/libssh/sftp_priv.h
@@ -32,6 +32,27 @@ int buffer_add_attributes(ssh_buffer buffer, sftp_attributes attr);
 sftp_attributes sftp_parse_attr(sftp_session session,
                                 ssh_buffer buf,
                                 int expectname);
+/**
+ * @brief Handle the sftp_init request from client.
+ *
+ * @param  client_msg         The pointer to client message.
+ *
+ * @return                    0 on success, < 0 on error with ssh and sftp error set.
+ *
+ * @see sftp_get_error()
+ */
+int sftp_process_init_packet(sftp_client_message client_msg);
+/**
+ * @brief Decode the data from channel buffer into sftp read_packet.
+ *
+ * @param  sftp         The sftp session handle.
+ *
+ * @param  data         The pointer to the data buffer of channel.
+ * @param  len          The data buffer length
+ *
+ * @return              Length of data decoded.
+ */
+int sftp_decode_channel_data_to_packet(sftp_session sftp, void *data);
 
 #ifdef __cplusplus
 }
diff --git a/src/libssh.map b/src/libssh.map
index eeb625c5..f81d8abe 100644
--- a/src/libssh.map
+++ b/src/libssh.map
@@ -459,3 +459,10 @@ LIBSSH_4_9_0    # Released
         ssh_vlog;
 } LIBSSH_4_8_1;
 
+LIBSSH_AFTER_4_9_0
+{
+    global:
+        sftp_channel_default_data_callback;
+        sftp_channel_default_subsystem_request;
+} LIBSSH_4_9_0;
+
diff --git a/src/sftpserver.c b/src/sftpserver.c
index 2b974905..cbdfcc88 100644
--- a/src/sftpserver.c
+++ b/src/sftpserver.c
@@ -258,7 +258,15 @@ sftp_client_message sftp_get_client_message(sftp_session sftp)
     return sftp_make_client_message(sftp, packet);
 }
 
-sftp_client_message sftp_get_client_message_from_packet(sftp_session sftp)
+/**
+ * @brief Get the client message from a sftp packet.
+ *
+ * @param  sftp         The sftp session handle.
+ *
+ * @return              The pointer to the generated sftp client message.
+ */
+static sftp_client_message
+sftp_get_client_message_from_packet(sftp_session sftp)
 {
     sftp_packet packet = NULL;
 
@@ -505,7 +513,19 @@ int sftp_reply_data(sftp_client_message msg, const void *data, int len) {
   return 0;
 }
 
-int sftp_reply_statvfs(sftp_client_message msg, sftp_statvfs_t st)
+/**
+ * @brief Handle the statvfs request, return information the mounted file system.
+ *
+ * @param  msg          The sftp client message.
+ *
+ * @param  st           The statvfs state of target file.
+ *
+ * @return              0 on success, < 0 on error with ssh and sftp error set.
+ *
+ * @see sftp_get_error()
+ */
+static int
+sftp_reply_statvfs(sftp_client_message msg, sftp_statvfs_t st)
 {
   int ret = 0;
   ssh_buffer out;