concepts changedagents-and-tools/mcp-tunnels/concepts
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1515| Term | Definition | Also appears as |
1616| ----------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
1717| **Tunnel stack** | The two containers you run inside your network to attach to a tunnel: the proxy and cloudflared. One stack serves one tunnel and can be replicated across hosts for availability. With programmatic access, the setup component runs alongside the stack to provision credentials. | the stack, the MCP tunnel stack, the tunnel deployment, your deployment |
18| **Proxy** | Anthropic's routing component. Terminates inner TLS, validates that upstream IPs fall within an allowed range, and routes each request to an upstream MCP server based on hostname. | `mcp-proxy` (image name, Compose service name, and Helm container name), `mcp-gateway` (container-internal config path `/etc/mcp-gateway/config.yaml` and Helm `gateway.config.*` values prefix) |
19| **cloudflared** | Cloudflare's open-source tunnel connector. Initiates the outbound-only connections from your network to the tunnel edge and carries encrypted traffic between the edge and the proxy. Not related to a Managed Agent. | the outbound connector, the tunnel connector |
18| **Proxy** | Anthropic’s routing component. Terminates inner TLS, validates that upstream IPs fall within an allowed range, and routes each request to an upstream MCP server based on hostname. | `mcp-proxy` (image name, Compose service name, and Helm container name), `mcp-gateway` (container-internal config path `/etc/mcp-gateway/config.yaml` and Helm `gateway.config.*` values prefix) |
19| **cloudflared** | Cloudflare’s open-source tunnel connector. Initiates the outbound-only connections from your network to the tunnel edge and carries encrypted traffic between the edge and the proxy. Not related to a Managed Agent. | the outbound connector, the tunnel connector |
2020| **Setup component** | The `setup` binary, shipped inside the `mcp-proxy` image. With programmatic access it authenticates over Workload Identity Federation, fetches the tunnel token, generates a CA and server certificate, and registers the CA with Anthropic. Also provides `renew-cert`. | setup Job (the Helm pre-install hook), `setup` service (the Compose profile), setup hook, setup binary, setup CLI |
2121| **Tunnel edge** | The Cloudflare edge servers that cloudflared dials out to (IP ranges `198.41.192.0/19` and `2606:4700:a0::/44`, port 7844 TCP and UDP). The tunnel that runs over them is provisioned and controlled by Anthropic; Cloudflare operates the underlying network. | the edge, the Anthropic-operated tunnel edge |
22| **Inner TLS** | A second TLS handshake carried inside the tunnel's plaintext WebSocket stream, between Anthropic's back end and your proxy. The proxy presents a server certificate signed by a CA you registered on the tunnel. Because only you hold the private key, the transport provider cannot read request or response payloads. | the inner TLS handshake |
22| **Inner TLS** | A second TLS handshake carried inside the tunnel’s plaintext WebSocket stream, between Anthropic’s back end and your proxy. The proxy presents a server certificate signed by a CA you registered on the tunnel. Because only you hold the private key, the transport provider cannot read request or response payloads. | the inner TLS handshake |
2323| **Upstream MCP server** | An MCP server running in your private network that the proxy routes to. Each upstream is exposed as one subdomain under your tunnel domain. | upstream, routed MCP server, tunneled MCP server |
2424
2525## Credential provisioning
2626
27The tunnel stack needs two credentials at runtime: the **tunnel token**, which authenticates cloudflared's outbound connection, and a **server certificate** signed by a CA registered on the tunnel, which the proxy presents during the inner TLS handshake. There are two ways to supply them, presented throughout this guide as a pair of tabs.
27The tunnel stack needs two credentials at runtime: the **tunnel token**, which authenticates cloudflared’s outbound connection, and a **server certificate** signed by a CA registered on the tunnel, which the proxy presents during the inner TLS handshake. There are two ways to supply them, presented throughout this guide as a pair of tabs.
2828
2929| Mode | How credentials reach the stack | Helm chart name | Tab label |
3030| ----------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------- | ------------------------------- |
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4040* **Connection direction:** cloudflared dials **outbound** from your network to the tunnel edge. Your firewall sees only egress on port 7844; no inbound port is opened.
4141* **Request direction:** once that connection is established, MCP requests travel **from Anthropic toward your network** over it, through cloudflared to the proxy, and on to the upstream MCP server.
4242
43The phrase "outbound-only" describes the connection, not the requests carried over it.
43The phrase “outbound-only” describes the connection, not the requests carried over it.
4444
45Inner TLS spans Anthropic's back end and your proxy. cloudflared and the tunnel edge sit between them on the wire but see only ciphertext; the proxy is the first place inside your network where MCP request payloads are readable.
45Inner TLS spans Anthropic’s back end and your proxy. cloudflared and the tunnel edge sit between them on the wire but see only ciphertext; the proxy is the first place inside your network where MCP request payloads are readable.
4646
4747```mermaid
4848sequenceDiagram
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