Update command-line-flags-for-tidb-configuration.md (#14038) (#14071)

command-line-flags-for-tidb-configuration.md

@@ -113,7 +113,7 @@ When you start the TiDB cluster, you can use command-line options or environment
 
 ## `--proxy-protocol-fallbackable`
 
-- Controls whether to enable PROXY protocol fallback mode. When this parameter is set to `true`, TiDB accepts PROXY client connections and client connections without any PROXY protocol header. By default, TiDB only accepts client connections with a PROXY protocol header.
+- Controls whether to enable PROXY protocol fallback mode. When this parameter is set to `true`, TiDB accepts client connections that belong to `--proxy-protocol-networks` without using the PROXY protocol specification or without sending a PROXY protocol header. By default, TiDB only accepts client connections that belong to `--proxy-protocol-networks` and send a PROXY protocol header.
 - Default value: `false`
 
 ## `--proxy-protocol-networks`

tidb-configuration-file.md

@@ -914,6 +914,11 @@ Configuration items related to the PROXY protocol.
 >
 > Use `*` with caution because it might introduce security risks by allowing a client of any IP address to report its IP address. In addition, using `*` might also cause the internal component that directly connects to TiDB (such as TiDB Dashboard) to be unavailable.
 
+### `fallbackable` <span class="version-mark">New in v6.5.1</span>
+
++ Controls whether to enable the PROXY protocol fallback mode. If this configuration item is set to `true`, TiDB can accept clients that belong to `proxy-protocol.networks` to connect to TiDB without using the PROXY protocol specification or without sending the PROXY protocol header. By default, TiDB only accepts client connections that belong to `proxy-protocol.networks` and send a PROXY protocol header.
++ Default value: `false`
+
 ## experimental
 
 The `experimental` section, introduced in v3.1.0, describes the configurations related to the experimental features of TiDB.