diff --git a/README.md b/README.md
index 8e850a1..186602a 100644
--- a/README.md
+++ b/README.md
@@ -16,39 +16,40 @@ This thing is built using [Golang](https://go.dev) and [drone-ssh](https://githu
 
 See [action.yml](./action.yml) for more detailed information.
 
-| Input Parameter         | Description                                                     | Default Value |
-|-------------------------|-----------------------------------------------------------------|---------------|
-| host                    | SSH host address                                                |               |
-| port                    | SSH port number                                                 | 22            |
-| passphrase              | SSH key passphrase                                              |               |
-| username                | SSH username                                                    |               |
-| password                | SSH password                                                    |               |
-| sync                    | Enable synchronous execution if multiple hosts                  | false         |
-| use_insecure_cipher     | Include more ciphers with use_insecure_cipher                   | false        |
-| cipher                  | Allowed cipher algorithms. If unspecified, a sensible default   |               |
-| timeout                 | Timeout duration for SSH to host                                | 30s           |
-| command_timeout         | Timeout duration for SSH command                                | 10m           |
-| key                     | Content of SSH private key. e.g., raw content of ~/.ssh/id_rsa  |               |
-| key_path                | Path of SSH private key                                         |               |
-| fingerprint             | SHA256 fingerprint of the host public key                       |               |
-| proxy_host              | SSH proxy host                                                  |               |
-| proxy_port              | SSH proxy port                                                  | 22            |
-| proxy_username          | SSH proxy username                                              |               |
-| proxy_password          | SSH proxy password                                              |               |
-| proxy_passphrase        | SSH proxy key passphrase                                        |               |
-| proxy_timeout           | Timeout for SSH to proxy host                                   | 30s           |
-| proxy_key               | Content of SSH proxy private key                                |               |
-| proxy_key_path          | Path of SSH proxy private key                                   |               |
-| proxy_fingerprint       | SHA256 fingerprint of the proxy host public key                 |               |
-| proxy_cipher            | Allowed cipher algorithms for the proxy                         |               |
-| proxy_use_insecure_cipher | Include more ciphers with use_insecure_cipher for the proxy   | false         |
-| script                  | Execute commands                                                |               |
-| script_stop             | Stop script after first failure                                 | false         |
-| envs                    | Pass environment variables to shell script                      |               |
-| envs_format             | Flexible configuration of environment value transfer            |               |
-| debug                   | Enable debug mode                                               | false         |
-| allenvs                 | pass the environment variables with prefix value of `GITHUB_` and `INPUT_` to the script | false |
-| request_pty             | Request a pseudo-terminal from the server                        | false              |
+| Input Parameter           | Description                                                                              | Default Value |
+|---------------------------|------------------------------------------------------------------------------------------|---------------|
+| host                      | SSH host address                                                                         |               |
+| port                      | SSH port number                                                                          | 22            |
+| passphrase                | SSH key passphrase                                                                       |               |
+| username                  | SSH username                                                                             |               |
+| password                  | SSH password                                                                             |               |
+| protocol                  | SSH protocol version (tcp, tcp4, tcp6)                                                   | tcp           |
+| sync                      | Enable synchronous execution if multiple hosts                                           | false         |
+| use_insecure_cipher       | Include more ciphers with use_insecure_cipher                                            | false         |
+| cipher                    | Allowed cipher algorithms. If unspecified, a sensible default                            |               |
+| timeout                   | Timeout duration for SSH to host                                                         | 30s           |
+| command_timeout           | Timeout duration for SSH command                                                         | 10m           |
+| key                       | Content of SSH private key. e.g., raw content of ~/.ssh/id_rsa                           |               |
+| key_path                  | Path of SSH private key                                                                  |               |
+| fingerprint               | SHA256 fingerprint of the host public key                                                |               |
+| proxy_host                | SSH proxy host                                                                           |               |
+| proxy_port                | SSH proxy port                                                                           | 22            |
+| proxy_username            | SSH proxy username                                                                       |               |
+| proxy_password            | SSH proxy password                                                                       |               |
+| proxy_passphrase          | SSH proxy key passphrase                                                                 |               |
+| proxy_timeout             | Timeout for SSH to proxy host                                                            | 30s           |
+| proxy_key                 | Content of SSH proxy private key                                                         |               |
+| proxy_key_path            | Path of SSH proxy private key                                                            |               |
+| proxy_fingerprint         | SHA256 fingerprint of the proxy host public key                                          |               |
+| proxy_cipher              | Allowed cipher algorithms for the proxy                                                  |               |
+| proxy_use_insecure_cipher | Include more ciphers with use_insecure_cipher for the proxy                              | false         |
+| script                    | Execute commands                                                                         |               |
+| script_stop               | Stop script after first failure                                                          | false         |
+| envs                      | Pass environment variables to shell script                                               |               |
+| envs_format               | Flexible configuration of environment value transfer                                     |               |
+| debug                     | Enable debug mode                                                                        | false         |
+| allenvs                   | pass the environment variables with prefix value of `GITHUB_` and `INPUT_` to the script | false         |
+| request_pty               | Request a pseudo-terminal from the server                                                | false         |
 
 ## Usage