[Hardening] F-12: Absence of Per-Account or Per-User Source CIDR Allowlist.

### The required feature described as a wish

**Description:** CloudStack does not provide a built-in mechanism to restrict per-account or per-user access to a defined set of source IP addresses or CIDR ranges. Any IP address that can reach the management plane can attempt to authenticate as any account.

**Affected Components:** Management UI / API

**Impact:** Without source IP allowlisting, a stolen API key or compromised credential set can be used from any network location globally. There is no network-level control to limit the blast radius of a credential compromise. High-privilege service accounts are particularly at risk, as they can be accessed from unexpected locations without raising any flags.

**Steps to Reproduce:**
- This finding is not directly reproducible since it reflects the absence of a control.

**Recommended Remediation:** Implement a per-account or per-user source CIDR allowlist field in the data model. Requests originating from IPs outside the defined allowlist should be rejected and logged as a security event.

該 issue 指出了 Management UI/API、account 或 user 資料模型、請求來源 IP 檢查以及 Security-Event 記錄，但沒有列出檔案或測試。首先定位這些入口點，並追蹤 API 請求的 authentication 和 authorization。完成時應包括按 account 或 user 定義的 CIDR 策略、拒絕策略範圍之外的請求，以及記錄 Security-Events，並涵蓋相關行為。

由索引模型根據 Issue 內容生成。