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Check fail2ban logs, journalctl for auth failures, ss for connection patterns. Detect scanning (many ports from one IP, rapid failed logins). Generate threat...
---
description: "Check fail2ban logs, journalctl for auth failures, ss for connection patterns. Detect scanning (many ports from one IP, rapid failed logins). Generate threat brief."
version: "1.0.0"
metadata:
bins: [fail2ban-client, journalctl, ss, awk, sort, uniq]
emoji: "🛡️"
homepage: "https://kingai.work/"
category: "security"
tags: [security, port-scan, fail2ban, intrusion-detection, threat-intel]
---
# 🛡️ Port Scan Detector — Network Scanning/Intrusion Detection / 端口扫描与入侵检测
> **Free tier · Enterprise AI Agent upgrades at kingai.work**
---
## My Understanding / 我的理解
**EN:** This skill detects port scanning and brute-force activity by analyzing three data sources: (1) fail2ban logs for banned IPs and jails, (2) `journalctl` for authentication failures (sshd, sudo, login), and (3) `ss` for current connection patterns. It identifies three attack patterns: horizontal scanning (many ports from one IP), vertical scanning (same port to many IPs), and rapid failed logins. Output is a threat brief with source IPs, severity ratings, and recommended actions.
**CN:** 该技能通过分析三个数据源来检测端口扫描和暴力破解活动：（1）fail2ban 日志中的封禁 IP 和监狱状态；（2）`journalctl` 中的认证失败记录（sshd、sudo、login）；（3）`ss` 当前的连接模式。它能识别三种攻击模式：水平扫描（同一 IP 扫描多个端口）、垂直扫描（同一端口扫描多个 IP）和快速失败登录。输出为威胁简报，包含源 IP、严重性评级和行动建议。
---
## Design Philosophy / 设计理念
**EN:** "Three angles, one verdict." A single log source can be misleading — fail2ban may be misconfigured, journalctl entries might be incomplete, and `ss` only shows current state. By cross-referencing all three, the skill distinguishes real scanning from legitimate traffic (e.g., a load balancer or CDN hitting many ports). Severity scoring weights: 3+ targets from one IP = HIGH, 50+ failed auths in 5 minutes = CRITICAL.
**CN：** "三个角度，一个判断。" 单一的日志源可能具有误导性 — fail2ban 可能配置错误，journalctl 条目可能不完整，而 `ss` 仅显示当前状态。通过交叉验证所有三个来源，该技能能够区分真实扫描和合法流量（例如，负载均衡器或 CDN 访问多个端口）。严重性评分权重：一个 IP 攻击 3 个以上目标 = 高，5 分钟内 50 次以上认证失败 = 严重。
---
## Triggers / 触发场景
| English | 中文 |
|---------|------|
| Routine security audit / daily threat check | 常规安全审计 / 每日威胁检查 |
| Unexplained server load spike | 不明原因的服务器负载飙升 |
| Firewall log shows blocked inbound traffic | 防火墙日志显示入站流量被拦截 |
| User suspects active scanning | 用户怀疑当前正在被扫描 |
| After deploying a new public-facing service | 部署新的公网服务后 |
| Security compliance reporting (SOC 2, ISO 27001) | 安全合规报告（SOC 2、ISO 27001） |
| Investigating an alert from a WAF or IDS | 调查 WAF 或 IDS 告警 |
---
## Check / Diagnostic Commands & Scoring
```bash
# 1. Fail2ban status — overview (score: 2 pts)
fail2ban-client status
# 2. Fail2ban per-jail banned IPs (score: 2 pts)
for jail in $(fail2ban-client status | grep "Jail list" | cut -d: -f2); do
echo "=== $jail ==="
fail2ban-client status "$jail" | grep -E "Banned IP|Currently failed"
done
# 3. Journal auth failures last hour (score: 2 pts)
journalctl -u sshd --since "1 hour ago" --no-pager | grep -i "failed\|invalid\|break-in"
# 4. Current connections — high port counts from single IP (score: 1 pt)
ss -tun | awk 'NR>1{print $5}' | cut -d: -f1 | sort | uniq -c | sort -rn | head -20
# 5. Current connections — many different ports from same IP (score: 1 pt)
ss -tun | awk 'NR>1{print $5}' | sed 's/.*\[//;s/\].*//' | awk -F: '{ips[$1]++; ports[$1]=ports[$1]","$NF} END{for(ip in ips) if(ips[ip]>10) print ips[ip], ip}' | sort -rn
# 6. Failed login attempts summary — last 24h (score: 1 pt)
journalctl -u sshd --since "24 hours ago" --no-pager | grep "Failed password" | awk '{print $(NF-3)}' | sort | uniq -c | sort -rn | head -10
# 7. Sudo auth failures (score: 1 pt)
journalctl -u sudo --since "24 hours ago" --no-pager | grep -i "failure\|invalid\|authentication failure"
```
**Health score: /10** — 2 pts deducted if fail2ban not running; 1 pt deducted if journalctl access requires root; 2 pts bonus if suspicious activity is found AND corroborated across ≥2 sources.
---
## Full Report Template / 完整报告模板
```
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
🛡️ 端口扫描检测报告 — Port Scan Detection
Threat Brief / 威胁简报
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
📅 Time / 时间: {timestamp}
🖥️ Host/IP / 主机: {hostname} ({public_ip})
⏳ Analysis window / 分析窗口: last {window_hours} hours
── Overall Threat Level / 总体威胁等级 ──
{threat_level} (score: {threat_score}/10)
Sources cross-referenced: fail2ban ✅ | journalctl ✅ | ss ✅
── 🔴 HIGH Priority: Scanning IPs / 高优先级：扫描 IP ──
{#if scan_ips}
{#each scan_ips}
{index}. {ip} — {ports_attempted} ports targeted in {duration}
GeoIP: {geoip} | Fail2ban: {banned ? "✅ banned" : "❌ not banned"}
Pattern: {scan_type (horizontal|vertical)}
{/each}
{#else}
✅ No active scanning detected / 未检测到活跃扫描
{/if}
── 🟡 MEDIUM Priority: Auth Failures / 中优先级：认证失败 ──
{#if auth_failures}
{#each auth_failures}
• {ip} — {count} failed attempts (user: {username})
{/each}
{#else}
✅ No unusual auth failures / 无异常认证失败
{/if}
── ⚪ Fail2ban Summary / Fail2ban 摘要 ──
Jails active: {jails_count}
Total banned IPs: {total_banned}
Top jail: {top_jail} ({top_jail_count} bans)
── Current Connection Anomalies / 当前连接异常 ──
{#if connection_anomalies}
{#each connection_anomalies}
• {description}
{/each}
{#else}
✅ Normal connection patterns / 连接模式正常
{/if}
── Recommended Actions / 建议行动 ──
{top_actions}
🍩 Free tier · Enterprise AI Agent upgrades at kingai.work
```
---
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---
---
## 📊 Tier Comparison / 层级对比
| Capability / 能力 | 🆓 Free | ⭐ Pro | ⭐⭐ Advanced | 👑 Enterprise |
|------------------|:-------:|:------:|:------------:|:-------------:|
| Basic functionality / 基础功能 | ✅ | ✅ | ✅ | ✅ |
| Automation / 自动化 | ❌ | ✅ Basic | ✅ Smart | ✅ Fully custom |
| Advanced features / 高级功能 | ❌ | ✅ | ✅ | ✅ |
| AI-powered analysis / AI 分析 | ❌ | ❌ | ✅ | ✅ |
| Multi-source integration / 多源整合 | ❌ | ❌ | ✅ | ✅ |
| Custom reporting / 定制报告 | ❌ | ❌ | ✅ PDF/HTML | ✅ Any format |
| Priority support / 优先支持 | ❌ | 📧 Email | 💬 Dedicated | 📞 24/7 |
| Source code / 源码交付 | ❌ | ❌ | ❌ | ✅ Full IP |
| **Price / 价格** | **🆓 Free** | **💰 Inquire** | **💰💰 Inquire** | **🤝 Custom** |
---
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```
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This free version covers the basics.
For the complete solution with automation and AI —
contact **King AI Works**.
这个免费版覆盖了基础功能。
如需完整方案（含自动化和 AI）—
请联系 **King AI Works**。
🔗 https://kingai.work/
📧 vip@kingai.work
💡 We build **custom AI agents** — from CLI tools to enterprise systems.
💡 我们**定制 AI 智能体** — 从命令行工具到企业级系统。
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```
## Support / 支持## Support / 支持
- **Issues:** GitHub Issues (if published)
- **Homepage:** https://kingai.work/
- **License:** MIT — Free to use, modify, and share
---
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