nat1

Expose your local service to Internet in NAT1 network.

Maintain the mapped address automatically.
Bind the mapped address to SVCB record.
Support both TCP and UDP.

Single mapping

Install the command line tool:

go install github.com/koho/nat1/cmd/nat1@latest

Zero config

A NAT entry is automatically created on gateway.

Note: The gateway needs to have UPnP enabled.

# export local port 3389
nat1 tcp 3389

Manual config

Create a public address mapping only. You need to manually configure the local address mapping on gateway (See Port forwarding).

# random local port
nat1 tcp
# fixed local port
nat1 tcp -l :5000

Multiple mappings

Bind the mapped address to DNS SVCB record. Currently only dnspod is supported.

Install the command line tool:

go install github.com/koho/nat1/cmd/nat1s@latest

An example config file:

{
  "dns": "xxx.dnspod.net:53",
  "dnspod": {
    "secret_id": "",
    "secret_key": ""
  },
  "service": [
    {
      "domain": "svc1.example.com",
      "local": "0.0.0.0:50000",
      "alpn": ["wg"],
      "network": "udp"  
    },
    {
      "domain": "svc2.example.com",
      "local": "0.0.0.0:50001",
      "alpn": ["h2"],
      "hint": true,
      "network": "tcp"
    }
  ]
}

Run the service with the following command:

nat1s config.json

Port forwarding

For each service, add corresponding forwarding rules to the router.

sudo iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 50001 -j DNAT --to-destination 192.168.1.55:443

Lookup domain

Your can find your mapped address using dig or https://www.nslookup.io/svcb-lookup/.