XTLS_Xray-docs-next/docs/en/config/outbounds/vless.md

VLESS (XTLS Vision Seed)

VLESS is a stateless lightweight transport protocol. It consists of inbound and outbound parts and can serve as a bridge between the Xray client and server.

Unlike VMess, VLESS does not depend on system time. The authentication method is also UUID.

OutboundConfigurationObject

OutboundConfigurationObject corresponds to the settings item in OutboundObject.

{
  "outbounds": [
    {
      // ...
      "protocol": "vless",
      "settings": {
        // [!code focus:7]
        "address": "example.com",
        "port": 443,
        "id": "5783a3e7-e373-51cd-8642-c83782b807c5",
        "encryption": "none",
        "flow": "xtls-rprx-vision",
        "level": 0,
        "reverse": {}
      }
    }
  ]
}

address: address

Server address, points to the server. Supports domain names, IPv4, and IPv6.

port: number

Server port, usually the same as the port the server is listening on.

id: string

User ID for VLESS. It can be any string less than 30 bytes, or a valid UUID. A custom string and its mapped UUID are equivalent. This means you can identify the same user in the configuration file by writing the ID in either way:

• Write "id": "我爱🍉老师1314",
• Or write "id": "5783a3e7-e373-51cd-8642-c83782b807c5" (This UUID is the UUID mapping of 我爱🍉老师1314)

The mapping standard is described in VLESS UUID Mapping Standard: Mapping Custom Strings to UUIDv5.

You can use the command xray uuid -i "custom string" to generate the UUID mapped from a custom string, or use the command xray uuid to generate a random UUID.

encryption: "none"

VLESS Encryption settings. Cannot be left empty; to disable, explicitly set to "none".

It is recommended for most users to use ./xray vlessenc to automatically generate this field to ensure no errors in writing. The detailed configuration below is recommended only for advanced users.

Its format is a detailed configuration string of fields connected by .. For example: mlkem768x25519plus.native.0rtt.100-111-1111.75-0-111.50-0-3333.ptjHQxBQxTJ9MWr2cd5qWIflBSACHOevTauCQwa_71U. This document will refer to the separate parts separated by dots as "blocks".

• The 1st block is the handshake method. Currently, there is only mlkem768x25519plus. Requires consistency between server and client.
• The 2nd block is the encryption method. Options are native/xorpub/random, corresponding to: raw format packet / raw format + obfuscated public key part / fully random numbers (similar to VMESS/Shadowsocks). Requires consistency between server and client.
• The 3rd block is session resumption. Choosing 0rtt will follow the server settings to attempt to use previously generated tickets to skip the handshake for fast connection (can be manually disabled by the server). Choosing 1rtt will force a 1-RTT handshake process. The meaning here differs from the server setting; see VLESS Inbound decryption settings for details.

Following blocks are padding. After the connection is established, the client sends some garbage data to obfuscate length characteristics. It does not need to be the same as the server (the corresponding part in the inbound is the padding sent from the server to the client). It is a variable-length part with the format padding.delay.padding + (.delay.padding) × n (multiple padding blocks can be inserted, requiring a delay block between two padding blocks). For example, you can write a very long padding.delay.padding.delay.padding.delay.padding.delay.padding.delay.padding.

• padding format is probability-min-max. E.g., 100-111-1111 means 100% probability to send a padding of length 111~1111.
• delay format is also probability-min-max. E.g., 75-0-111 means 75% probability to wait 0~111 milliseconds.

The first padding block has special requirements: probability must be 100% and minimum length greater than 0. If no padding exists, the core automatically uses 100-111-1111.75-0-111.50-0-3333 as the padding setting.

The last block will be recognized by the core as the parameter used to authenticate the server. It can be generated by ./xray x25519 (using the Password part) or ./xray mlkem768 (using the Client part). It must correspond to the server. mlkem768 belongs to post-quantum algorithms, preventing (future) client parameter leaks from allowing quantum computers to crack the private key and impersonate the server. This parameter is only used for verification; the handshake process is post-quantum secure regardless, and existing encrypted data cannot be decrypted by future quantum computers.

flow: string

Flow control mode, used to select the XTLS algorithm.

Currently, the following flow control modes are available in the outbound protocol:

• No flow or empty string: Use standard TLS proxy.
• xtls-rprx-vision: Use XTLS, including inner handshake random padding. Will intercept UDP traffic targeting port 443 (QUIC) to force browsers to use standard HTTPS, increasing traffic that can be Spliced.
• xtls-rprx-vision-udp443: Same as xtls-rprx-vision, but does not intercept UDP 443. Used when a program forces the use of QUIC and would fail to work if intercepted.

XTLS is available only in the following combinations:

• TCP+TLS/Reality: In this case, if transmitting TLS 1.3, the core will attempt to Splice encrypted data at the bottom layer. If successful, it saves all core IO overhead.
• VLESS Encryption: No underlying transport restrictions. If the underlying transport is not TCP, it only attempts to penetrate Encryption, saving Encryption overhead. If it is TCP, it will still attempt to perform Splice.

::: tip About Splice Splice is a function provided by the Linux Kernel. The system kernel forwards TCP directly, no longer passing through Xray's memory, greatly reducing data copying and CPU context switching.

When using Vision mode, Splice is automatically enabled if the following conditions are met:

• Linux environment.
• Inbound protocol is a pure TCP connection like Dokodemo door, Socks, HTTP, or other inbound protocols using XTLS.
• Outbound protocol is VLESS + XTLS.

When using Splice, the network speed display will lag and will only be counted after the connection is disconnected because the core cannot know the traffic situation while the kernel takes over the connection. :::

level: number

User level. The connection will use the Local Policy corresponding to this user level.

The value of level corresponds to the value of level in policy. If not specified, it defaults to 0.

reverse: struct

VLESS minimalist reverse proxy configuration. It preserves the real source IP information from the public-facing side.

The existence of this item indicates that this outbound can be used as a VLESS reverse proxy outbound, and it will automatically establish a connection to the server to register the reverse proxy tunnel.

"reverse": {
  "tag": "r-inbound",
  "sniffing" : {}
}

tag is the inbound proxy tag for this reverse proxy. When the server dispatches a reverse proxy request, it enters the routing system from the inbound using this tag, and the routing system routes it to the outbound you need.

The UUID used must be one that is also configured with reverse on the server side (see VLESS Inbound for details).

sniffing see sniffingObject, performs sniffing on requests entering through this reverse proxy.

::: tip Full tutorial: VLESS Reverse Proxy Examples :::