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+# reverse proxy
+# principle
+Xray Client <--- VMESS/SS ---> Xray Portal (requires public IP) <--- VMESS/SS ---> Xray Bridge
+# illustrate
+In the configuration, the internal network device uses `bridge.json`, the device with public network ip uses `portal.json`, and the device connected to the intranet through `portal` uses `client.json`.
+
+In practical applications, `VMESS-TCP, Shadowsocks-2022`, etc. can be used as the transmission protocols from Xray Client to Xray Portal, and from Xray Bridge to Xray Portal.
+
+## psk
+
+Shadowsocks 2022 uses a pre-shared key similar to WireGuard for the password.
+
+Use `openssl rand -base64 <length>` to generate a shadowsocks-rust compatible key, the length depends on the encryption method used.
+
+| encryption method | key length |
+|--------------------------------|-----:|
+| 2022-blake3-aes-128-gcm | 16 |
+| 2022-blake3-aes-256-gcm | 32 |
+| 2022-blake3-chacha20-poly1305 | 32 |
+
+In the Go implementation, 32-bit keys always work.