> ## Documentation Index
> Fetch the complete documentation index at: https://docs.terrapinfinance.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Network access

> Allow the Terrapin hosts when your MCP client runs in a sandbox.

Most setups need nothing here. This page matters only if your assistant runs somewhere with restricted outbound network access: a container, an agent sandbox with a domain allowlist, or a corporate proxy.

## Hosts to allow

| Host                                | Used for                                                                  |
| ----------------------------------- | ------------------------------------------------------------------------- |
| `terrapinfinance.com`               | The MCP endpoint and every API call made through it.                      |
| `s3.eu-central-003.backblazeb2.com` | Document downloads, which return short-lived presigned URLs on this host. |

Both are needed. Over MCP, `download_document` returns a presigned URL rather than the file bytes, and fetching that URL is an ordinary network request that the sandbox's egress rules apply to. Allowing only `terrapinfinance.com` produces the most common symptom we see: the assistant finds and lists documents happily, then reports that it located them but cannot read them.

<Warning>
  Allowlist both hosts by name. Presigned URLs carry a signature bound to the host in the URL, so routing them through a rewriting proxy or a different S3 endpoint invalidates the signature and returns 403.
</Warning>

## Where to set it

In Claude Desktop, the allowed-domains list is under **Settings → Capabilities → Network access** on Free, Pro, and Max. On Team and Enterprise it is an administrator policy under **Organization settings → Capabilities → Code execution → Allow network egress**, and the in-app setting will not override it.

In Claude Code, run `/sandbox` to inspect the current policy, or add the hosts to `sandbox.network.allowedDomains` in `~/.claude/settings.json`:

```json settings.json theme={"theme":{"light":"catppuccin-latte","dark":"github-dark-high-contrast"}}
{
  "sandbox": {
    "network": {
      "allowedDomains": [
        "terrapinfinance.com",
        "s3.eu-central-003.backblazeb2.com"
      ]
    }
  }
}
```

Network policy is read when a session starts, so open a new conversation before testing. A corporate proxy also has to let `POST https://terrapinfinance.com/mcp` through with the `Authorization` header intact; proxies that strip it make every call fail with 401.