README.md in embulk-input-ftp-0.1.3 vs README.md in embulk-input-ftp-0.1.4

@@ -1,26 +1,47 @@
 # FTP file input plugin for Embulk
 
 ## Overview
 
+This plugin support **FTP**, **FTPES(FTPS explicit)**, **FTPS(FTPS implicit)** and doesn't support **SFTP**.
+
+If you want to use SFTP, please use [embulk-input-sftp](https://github.com/embulk/embulk-input-sftp).
+
+
 * **Plugin type**: file input
 * **Resume supported**: yes
 * **Cleanup supported**: yes
 
 ## Configuration
 
 - **host**: FTP server address (string, required)
-- **port**: FTP server port number (integer, default: `21`. `990` if `ssl` is true)
+- **port**: FTP server port number (integer, default: `21`. `990` if `ssl` is true and `ssl_explicit` is false)
 - **user**: user name to login (string, optional)
 - **password**: password to login (string, default: `""`)
 - **path_prefix** prefix of target files (string, required)
+- **incremental** enables incremental loading(boolean, optional. default: true. If incremental loading is enabled, config diff for the next execution will include last_path parameter so that next execution skips files before the path. Otherwise, last_path will not be included.
 - **passive_mode**: use passive mode (boolean, default: true)
 - **ascii_mode**: use ASCII mode instead of binary mode (boolean, default: false)
 - **ssl**: use FTPS (SSL encryption). (boolean, default: false)
+- **ssl_explicit** use FTPS(explicit) instead of FTPS(implicit). (boolean, default:true)
 - **ssl_verify**: verify the certification provided by the server. By default, connection fails if the server certification is not signed by one the CAs in JVM's default trusted CA list. (boolean, default: true)
 - **ssl_verify_hostname**: verify server's hostname matches with provided certificate. (boolean, default: true)
 - **ssl_trusted_ca_cert_file**: if the server certification is not signed by a certificate authority, set path to the X.508 certification file (pem file) of a private CA (string, optional)
 - **ssl_trusted_ca_cert_data**: similar to `ssl_trusted_ca_cert_file` but embed the contents of the PEM file as a string value instead of path to a local file (string, optional)
+
+### FTP / FTPS default port number
+
+FTP and FTPS server usually listens following port number(TCP) as default.
+
+Please be sure to configure firewall rules.
+
+|                         | FTP | FTPS(explicit) = FTPES | FTPS(implicit) = FTPS |
+|:------------------------|----:|-----------------------:|----------------------:|
+| Control channel port    |  21 |                     21 |             990 (\*1) |
+| Data channel port (\*2) |  20 |                     20 |                   989 |
+
+1. If you're using both of FTPS(implicit) and FTP, server may also listen 21/TCP for unecnrypted FTP.
+2. If you're using `passive mode`, data channel port can be taken between 1024 and 65535.
 
 ## Example
 
 Simple FTP: