AnyTLS

Since sing-box 1.12.0

Structure

{
  "type": "anytls",
  "tag": "anytls-out",

  "server": "127.0.0.1",
  "server_port": 1080,
  "password": "8JCsPssfgS8tiRwiMlhARg==",
  "idle_session_check_interval": "30s",
  "idle_session_timeout": "30s",
  "min_idle_session": 5,
    "ensure_idle_session": 10,
    "heartbeat": "30s",
    "min_idle_session_for_age": 2,
    "max_connection_lifetime": "300s",
    "connection_lifetime_jitter": "10s",
    "ensure_idle_session_create_rate": 5,
    "close_after_idle": "",
    "close_after_lifetime": "",
    "client_metadata": "",
  "tls": {},

  ... // Dial Fields
}

Fields

server

Required

The server address.

server_port

Required

The server port.

password

Required

The AnyTLS password.

idle_session_check_interval

Interval of the pool maintenance that applies idle_session_timeout, max_connection_lifetime, ensure_idle_session, close_after_idle and close_after_lifetime to idle sessions. Default: 30s. A value of 5s or less is replaced by the default.

idle_session_timeout

In the check, close sessions that have been idle for longer than this, except those kept by min_idle_session. Default: 30s. A value of 5s or less is replaced by the default.

min_idle_session

In the check, keep at least n idle sessions open, counting those not yet past idle_session_timeout. The expired sessions kept are the lowest-latency ones, see Session selection. Default: 0.

ensure_idle_session

Target number of idle sessions to maintain in the pool. Each check dials the missing ones, at most ensure_idle_session_create_rate at a time.

heartbeat

Interval for sending heartbeat packets to keep sessions alive.

Each heartbeat round trip also refreshes the session's latency, see Session selection.

min_idle_session_for_age

Minimum number of idle sessions that max_connection_lifetime leaves open. When it has to choose, it keeps the lowest-latency ones.

max_connection_lifetime

Maximum age of a session. In each check, idle sessions past it are closed, the highest-latency ones first, while at least min_idle_session_for_age idle sessions stay open. A session carrying a connection is not affected and can still be reused after it is past this age; use close_after_lifetime to stop reusing old sessions.

connection_lifetime_jitter

Random jitter applied to max_connection_lifetime. Each session's lifetime is drawn uniformly between max_connection_lifetime minus and plus this value, and is at least one second, so sessions created together do not expire together.

ensure_idle_session_create_rate

Maximum rate at which new idle sessions are created per interval.

close_after_idle

Close a session that has been idle for longer than this. Disabled when empty.

Unlike idle_session_timeout, it ignores min_idle_session and ensure_idle_session, so a session that new connections keep passing over, such as a slow one, is always replaced; ensure_idle_session dials a fresh session in its place. Sessions are checked every idle_session_check_interval.

Without traffic, the sessions kept by ensure_idle_session are replaced once per close_after_idle.

close_after_lifetime

Stop reusing a session older than this, and close it. Disabled when empty.

Each session's limit is drawn between 90% and 100% of this value, so sessions created together do not all retire at once. From then on the session is never given a new connection. It closes at once when idle, and otherwise as soon as the connection it carries ends, so no connection is interrupted. A connection that stays open keeps its session alive until it ends.

Unlike max_connection_lifetime, it ignores min_idle_session_for_age.

client_metadata

Since sing-box 1.13.16

Check AnyTLS client metadata.

tls

Required

TLS configuration, see TLS.

Session selection

The client measures the end-to-end latency of every session itself, so no server support is needed. A session sends its settings as soon as it is opened and is timed by the server's reply, and every heartbeat adds another sample to a smoothed average.

• A new connection uses the idle session with the lowest latency. Sessions not yet measured come after measured ones, newest first.
• Sessions closed by max_connection_lifetime are the highest-latency ones first, with unmeasured ones before them; min_idle_session_for_age keeps the lowest-latency ones.
• min_idle_session likewise keeps the lowest-latency idle sessions open.

Pre-created sessions from ensure_idle_session are measured right after they connect, before they carry any traffic. Without heartbeat, a session's latency is only measured once.

At debug level every new connection logs an anytls.session.selected event describing its session. Durations are in milliseconds and times in UTC.

Field	Meaning
session	Session number, from 1
source	pool for an idle session reused, new for one dialed for this connection
streams	Connections opened on the session, this one included
created_at, age	When the session was created, and its age
idle_for	How long a reused session was idle
latency, latency_last, latency_samples	Smoothed and latest latency, and the number of samples; the first two are omitted until measured
max_lifetime, expires_at, lifetime_left	The session's lifetime with jitter, when it expires, and the time left, negative once expired; omitted without max_connection_lifetime
retire_at, retire_left	When the session stops being reused under close_after_lifetime, and the time left; omitted without it
idle_sessions, total_sessions	Idle and total sessions after the pick

Dial Fields

See Dial Fields for details.