sing-box/docs/configuration/inbound/tun.md

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Linux and Windows only

Structure

{
  "inbounds": [
    {
      "type": "tun",
      "tag": "tun-in",

      "inet4_address": "172.19.0.1/30",
      "inet6_address": "fdfe:dcba:9876::1/128",
      "mtu": 1500,
      "auto_route": true,
      "endpoint_independent_nat": false,
      "udp_timeout": 300,
      
      "sniff": true,
      "sniff_override_destination": false,
      "domain_strategy": "prefer_ipv4"
    }
  ]
}

Tun Fields

inet4_address

==Required==

IPv4 prefix for the tun interface.

inet6_address

IPv6 prefix for the tun interface.

mtu

The maximum transmission unit.

auto_route

Set the default route to the Tun.

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To avoid traffic loopback, set `route.auto_detect_interface` or `route.default_interface` or `outbound.bind_interface`

endpoint_independent_nat

Enabled endpoint-independent NAT.

Performance may degrade slightly, so it is not recommended to enable on when it is not needed.

udp_timeout

UDP NAT expiration time in seconds, default is 300 (5 minutes).

Listen Fields

sniff

Enable sniffing.

See Sniff for details.

sniff_override_destination

Override the connection destination address with the sniffed domain.

If the domain name is invalid (like tor), this will not work.

domain_strategy

One of prefer_ipv4 prefer_ipv6 ipv4_only ipv6_only.

If set, the requested domain name will be resolved to IP before routing.

If sniff_override_destination is in effect, its value will be taken as a fallback.