zrhe2016

cloudflare tunnel

Yes. Your understanding is correct.

A slightly more complete mental model is:

Traditional public service

Internet User
     │
     ▼
 Public IP
     │
     ▼
 Router/NAT
     │ Port Forward
     ▼
   Server

Cloudflare Tunnel changes the direction of the connection:

                 ┌───────────────┐
Internet User ──►│  Cloudflare   │
                 │  Edge Network │
                 └───────┬───────┘
                         │
                         │ Existing outbound tunnel
                         ▼
                    cloudflared
                         │
                         ▼
                  localhost:8080

The important point is that your server initiates an outbound connection to Cloudflare:

Server ───── outbound HTTPS/QUIC ─────► Cloudflare

So Cloudflare does not need to initiate a connection to your home/server network.

This means you generally do not need:

Public IPv4
Port forwarding
UPnP
NAT configuration
Opening 80/443 on the router

It also works well in situations like:

Home broadband behind CGNAT
      │
      ├── No public IPv4
      │
      ▼
cloudflared
      │
      ▼
Cloudflare Tunnel
      │
      ▼
https://app.example.com

For example, suppose your application listens only on:

127.0.0.1:3000

You can map:

app.example.com
      ↓
Cloudflare
      ↓
Tunnel
      ↓
127.0.0.1:3000

So from the user's perspective:

https://app.example.com

But the real server remains inaccessible directly from the Internet.

One distinction worth remembering:

Technology Main idea
Port forwarding Internet → your server
VPN Devices join the same private network
Cloudflare Tunnel Your server → Cloudflare ← users
Reverse proxy Proxy receives requests then forwards them
Reverse tunnel Backend actively establishes the tunnel outward

So Cloudflare Tunnel can be understood as roughly:

Reverse Tunnel
      +
Reverse Proxy
      +
Cloudflare Edge
      +
DNS / TLS / Access controls

The shortest summary is:

Cloudflare Tunnel turns “Internet needs to find my server” into “my server goes out and connects to Cloudflare first.”

This is why it is especially useful for no-public-IP / CGNAT / home server / internal web service scenarios.