Alibabacloud Network Reachability Analysis

NIS Network Reachability Analysis / NIS 网络可达性分析

Language / 语言: Respond in the same language the user uses. If the user speaks Chinese, use the Chinese (zh-CN) prompts below. If the user speaks English, use the English (en) prompts below.

Guides an agent through interactive network reachability analysis using Alibaba Cloud NIS. Covers forward/reverse path analysis, topology visualization (Mermaid), and monitoring diagnostics for resources along the path.

Architecture: NIS (CreateAndAnalyzeNetworkPath + GetNetworkReachableAnalysis) + CloudMonitor (DescribeMetricData)

⚠️ CRITICAL / 关键: READ-ONLY OPERATIONS ONLY

This skill performs read-only network diagnostics. DO NOT create, modify, or delete any cloud resources.

本技能仅执行只读网络诊断操作。严禁创建、修改或删除任何云资源。

Allowed: CreateAndAnalyzeNetworkPath, GetNetworkReachableAnalysis, DescribeMetricData, Describe* APIs

允许：分析任务创建与查询、监控数据查询、Describe* 类查询 API

Forbidden: Create* (except CreateAndAnalyzeNetworkPath), Modify*, Delete*, Start*, Stop*, Run* APIs

禁止：创建类 API（除 CreateAndAnalyzeNetworkPath 外）、修改、删除、启停、执行类 API

Installation

Pre-check: Aliyun CLI >= 3.3.1 required Run aliyun version to verify >= 3.3.1. If not installed or version too low, see references/cli-installation-guide.md for installation instructions. Then [MUST] run aliyun configure set --auto-plugin-install true to enable automatic plugin installation.

aliyun version
aliyun configure set --auto-plugin-install true

Authentication

Pre-check: Alibaba Cloud Credentials Required

Security Rules:

• NEVER read, echo, or print AK/SK values (e.g., echo $ALIBABA_CLOUD_ACCESS_KEY_ID is FORBIDDEN)
• NEVER ask the user to input AK/SK directly in the conversation or command line
• NEVER use aliyun configure set with literal credential values
• ONLY use aliyun configure list to check credential status

aliyun configure list --user-agent AlibabaCloud-Agent-Skills

Check the output for a valid profile (AK, STS, or OAuth identity).

If no valid profile exists, STOP here.

1. Obtain credentials from Alibaba Cloud Console
2. Configure credentials outside of this session (via aliyun configure in terminal or environment variables in shell profile)
3. Return and re-run after aliyun configure list shows a valid profile

RAM Permissions

See references/ram-policies.md for the full RAM policy.

Required actions: nis:CreateAndAnalyzeNetworkPath, nis:GetNetworkReachableAnalysis, cms:DescribeMetricData.

Parameter Confirmation

IMPORTANT: Parameter Confirmation — Before executing any command or API call, ALL user-customizable parameters (e.g., RegionId, instance IDs, IP addresses, protocol, ports, resource types, etc.) MUST be confirmed with the user. Do NOT assume or use default values without explicit user approval.

Collect the following parameters interactively:

Interactive Collection Logic / 交互收集逻辑

Use the prompts matching the user's language:

Step 1 — Ask resource types / 询问资源类型

Step 2 — Type-specific prompts / 按类型提示

Step 3 — Protocol & ports / 协议和端口

Core Workflow

Step 1: Forward Path Analysis / 正向路径分析

aliyun nis create-and-analyze-network-path \
  --source-id <SourceId> \
  --source-type <SourceType> \
  --target-id <TargetId> \
  --target-type <TargetType> \
  --protocol <Protocol> \
  --target-port <TargetPort> \
  --source-ip-address <SourceIpAddress> \
  --target-ip-address <TargetIpAddress> \
  --region <RegionId> \
  --user-agent AlibabaCloud-Agent-Skills

Omit --source-ip-address / --target-ip-address if SourceType/TargetType is not vpn or vbr. Omit --target-port if Protocol is icmp.

Record the returned NetworkReachableAnalysisId.

⚠️ MANDATORY / 强制: ALWAYS perform reverse path analysis after forward analysis completes.

MUST execute Step 3 (Reverse Path Analysis) immediately after Step 2 finishes. Do NOT skip or omit reverse path check.

必须在正向分析完成后立即执行 Step 3（反向路径分析）。严禁跳过或省略反向路径检查。

Step 2: Poll for Forward Result / 轮询正向结果

aliyun nis get-network-reachable-analysis \
  --network-reachable-analysis-id <ForwardAnalysisId> \
  --region <RegionId> \
  --user-agent AlibabaCloud-Agent-Skills

Repeat until NetworkReachableAnalysisStatus is finish. Extract Reachable, NetworkReachableAnalysisResult.

Step 3: Reverse Path Analysis / 反向路径分析

Swap source and target / 交换源和目的:

• Forward SourceId/Type → Reverse TargetId/Type
• Forward TargetId/Type → Reverse SourceId/Type
• Forward SourceIpAddress → Reverse TargetIpAddress
• Forward TargetIpAddress → Reverse SourceIpAddress

Port handling / 端口处理:

• Reverse --source-port = Forward TargetPort (server listening port / 服务端监听端口)
• Reverse --target-port = Random ephemeral port in range 49152 ~ 65535 (client ephemeral port / 客户端随机端口)

Since the client initiates the connection with a dynamically assigned ephemeral port, the reverse path (server → client) should use a random port in the ephemeral range (49152-65535) as the target port to simulate real return traffic.

由于客户端发起连接时使用动态分配的临时端口，反向路径（服务端→客户端）的目的端口应使用临时端口范围（49152-65535）内的随机值来模拟真实回程流量。

aliyun nis create-and-analyze-network-path \
  --source-id <OriginalTargetId> \
  --source-type <OriginalTargetType> \
  --target-id <OriginalSourceId> \
  --target-type <OriginalSourceType> \
  --protocol <Protocol> \
  --source-port <OriginalTargetPort> \
  --target-port <RandomPort_49152_to_65535> \
  --source-ip-address <OriginalTargetIpAddress> \
  --target-ip-address <OriginalSourceIpAddress> \
  --region <RegionId> \
  --user-agent AlibabaCloud-Agent-Skills

Omit --source-ip-address / --target-ip-address if SourceType/TargetType is not vpn or vbr. 若源/目的类型不是 vpn 或 vbr，可省略 --source-ip-address / --target-ip-address。

Step 4: Poll for Reverse Result / 轮询反向结果

Same as Step 2, using the reverse NetworkReachableAnalysisId.

Step 5: Result Interpretation / 结果解读

CRITICAL / 关键: Always use topologyData.positive from the actively initiated analysis task. IGNORE topologyData.reverse in any response — it is unreliable.

始终使用主动发起的分析任务返回的 topologyData.positive。 忽略任何响应中的 topologyData.reverse——它不可靠。

For each direction (forward/reverse) / 对正向和反向分别：

1. Check Reachable field. If true, path is connected. / 检查 Reachable 字段，true 表示可达。
2. If false, analyze from NetworkReachableAnalysisResult: / 若为 false，分析以下字段定位阻断点：
   • errorCode — root cause code / 根因错误码
   • securityGroupData — security group rules blocking traffic / 安全组拦截规则
   • routeData — route table entries causing drops / 路由表丢包条目

Step 6: Topology Visualization / 拓扑可视化 (Mermaid)

Generate a Mermaid diagram from topologyData.positive:

graph LR

• Nodes: Extract nodeType and bizInsId from nodeList
• Links: Build directional edges from linkList

Example:

graph LR
    ECS_i-src["ECS: i-bp1xxx"] --> VRouter_vrt-1["VRouter: vrt-xxx"]
    VRouter_vrt-1 --> VSW_vsw-1["VSW: vsw-xxx"]
    VSW_vsw-1 --> ENI_eni-1["ENI: eni-xxx"]
    ENI_eni-1 --> ECS_i-dst["ECS: i-bp2xxx"]

Step 7: Resource Monitoring Diagnostics / 途经资源监控诊断

For resource IDs found in topologyData, if they match the prefixes below, query monitoring data for the last 1 hour: 对 topologyData 中途经的资源 ID，若匹配以下前缀，查询最近 1 小时监控数据：

Query command (CMS uses PascalCase API-style, not plugin mode):

aliyun cms DescribeMetricData \
  --Namespace <Namespace> \
  --MetricName <MetricName> \
  --Dimensions '[{"instanceId":"<ResourceId>"}]' \
  --StartTime <1HourAgoTimestamp> \
  --EndTime <NowTimestamp> \
  --Period 60 \
  --user-agent AlibabaCloud-Agent-Skills

Rate limit: 10 calls/second per account. Batch queries across multiple metrics should be paced accordingly.

Cleanup / 清理

NIS reachability analysis is read-only — no cloud resources are created or modified. No cleanup is required. NIS 可达性分析为只读操作——不会创建或修改任何云资源，无需清理。

Constraints / 使用限制

1. IPv4 only / 仅支持 IPv4 — Only IPv4 path analysis is supported.
2. Unidirectional / 单向分析 — Each analysis is one-way; reverse path requires a separate task with swapped source/target.
3. CMS quota / CMS 配额 — DescribeMetricData shares 1,000,000 free calls/month with other CMS query APIs.
4. CMS rate limit / CMS 频控 — 10 calls/second per account (including RAM users).

Best Practices / 最佳实践

1. Always perform both forward and reverse analysis to confirm bidirectional connectivity. / 始终执行正向+反向分析以确认双向连通性。
2. When path is unreachable, check security group rules and route tables first. / 路径不可达时，优先检查安全组规则和路由表。
3. For vpn/vbr scenarios, always provide On-Premise IP. / vpn/vbr 场景务必提供云下私网 IP。
4. Use Mermaid topology diagrams to visualize traffic paths. / 使用 Mermaid 拓扑图帮助用户可视化流量路径。
5. Query monitoring data only for resources on the actual path. / 仅查询实际路径上的资源监控数据以减少 API 调用。
6. Present monitoring anomalies alongside reachability results. / 将监控异常与可达性结果一并呈现，提供完整诊断。

References / 参考文件