sing-box/docs/configuration/route/rule_action.md

---

icon: material/new-box

!!! quote "Changes in sing-box 1.12.0"

:material-plus: [tls_fragment](#tls_fragment)  
:material-plus: [tls_fragment_fallback_delay](#tls_fragment_fallback_delay)

Final actions

route

{
  "action": "route", // default
  "outbound": "",
 
  ... // route-options Fields
}

!!! note ""

You can ignore the JSON Array [] tag when the content is only one item

route inherits the classic rule behavior of routing connection to the specified outbound.

outbound

==Required==

Tag of target outbound.

route-options Fields

See route-options fields below.

reject

{
  "action": "reject",
  "method": "default", // default
  "no_drop": false
}

reject reject connections

The specified method is used for reject tun connections if sniff action has not been performed yet.

For non-tun connections and already established connections, will just be closed.

method

• default: Reply with TCP RST for TCP connections, and ICMP port unreachable for UDP packets.
• drop: Drop packets.

no_drop

If not enabled, method will be temporarily overwritten to drop after 50 triggers in 30s.

Not available when method is set to drop.

hijack-dns

{
  "action": "hijack-dns"
}

hijack-dns hijack DNS requests to the sing-box DNS module.

Non-final actions

route-options

{
  "action": "route-options",
  "override_address": "",
  "override_port": 0,
  "network_strategy": "",
  "fallback_delay": "",
  "udp_disable_domain_unmapping": false,
  "udp_connect": false,
  "udp_timeout": "",
  "tls_fragment": false,
  "tls_fragment_fallback_delay": ""
}

route-options set options for routing.

override_address

Override the connection destination address.

override_port

Override the connection destination port.

network_strategy

See Dial Fields for details.

Only take effect if outbound is direct without outbound.bind_interface, outbound.inet4_bind_address and outbound.inet6_bind_address set.

network_type

See Dial Fields for details.

fallback_network_type

See Dial Fields for details.

fallback_delay

See Dial Fields for details.

udp_disable_domain_unmapping

If enabled, for UDP proxy requests addressed to a domain, the original packet address will be sent in the response instead of the mapped domain.

This option is used for compatibility with clients that do not support receiving UDP packets with domain addresses, such as Surge.

udp_connect

If enabled, attempts to connect UDP connection to the destination instead of listen.

udp_timeout

Timeout for UDP connections.

Setting a larger value than the UDP timeout in inbounds will have no effect.

Default value for protocol sniffed connections:

Timeout	Protocol
10s	dns, ntp, stun
30s	quic, dtls

If no protocol is sniffed, the following ports will be recognized as protocols by default:

Port	Protocol
53	dns
123	ntp
443	quic
3478	stun

tls_fragment

!!! question "Since sing-box 1.12.0"

Fragment TLS handshakes to bypass firewalls.

This feature is intended to circumvent simple firewalls based on plaintext packet matching, and should not be used to circumvent real censorship.

Since it is not designed for performance, it should not be applied to all connections, but only to server names that are known to be blocked.

On Linux, Apple platforms, (administrator privileges required) Windows, the wait time can be automatically detected, otherwise it will fall back to waiting for a fixed time specified by tls_fragment_fallback_delay.

In addition, if the actual wait time is less than 20ms, it will also fall back to waiting for a fixed time, because the target is considered to be local or behind a transparent proxy.

tls_fragment_fallback_delay

!!! question "Since sing-box 1.12.0"

The fallback value used when TLS segmentation cannot automatically determine the wait time.

500ms is used by default.

sniff

{
  "action": "sniff",
  "sniffer": [],
  "timeout": ""
}

sniff performs protocol sniffing on connections.

For deprecated inbound.sniff options, it is considered to sniff() performed before routing.

sniffer

Enabled sniffers.

All sniffers enabled by default.

Available protocol values an be found on in Protocol Sniff

timeout

Timeout for sniffing.

300ms is used by default.

resolve

{
  "action": "resolve",
  "strategy": "",
  "server": ""
}

resolve resolve request destination from domain to IP addresses.

strategy

DNS resolution strategy, available values are: prefer_ipv4, prefer_ipv6, ipv4_only, ipv6_only.

dns.strategy will be used by default.

server

Specifies DNS server tag to use instead of selecting through DNS routing.