feat: Security Audit Tab im Admin-Panel mit nftables/SSH/Fail2ban-Checks

internal/api/server.go

@@ -105,6 +105,7 @@ func (s *Server) routes() {
 	s.mux.HandleFunc("POST /api/admin/services/{name}/action", s.authMiddleware(s.requireRole(userstore.RoleAdmin, s.handleServiceAction)))
 
 	s.mux.HandleFunc("GET /api/admin/system/stats", s.authMiddleware(s.requireRole(userstore.RoleAdmin, s.handleSystemStats)))
+	s.mux.HandleFunc("GET /api/admin/security/audit", s.authMiddleware(s.requireRole(userstore.RoleAdmin, s.handleSecurityAudit)))
 
 	// Export routes
 	s.mux.HandleFunc("GET /api/export/pdf/{id}", s.authMiddleware(s.requireMailAccess(s.handleExportPDF)))
@@ -1489,3 +1490,111 @@ func mailRefToInfo(store *storage.Store, ref *storage.MailRef) *mailInfo {
 		Subject: pm.Subject,
 	}
 }
+
+// ── Security Audit ──────────────────────────────────────────────────────────
+
+type securityCheck struct {
+	Name    string `json:"name"`
+	Status  string `json:"status"` // "ok" | "warning" | "error"
+	Message string `json:"message"`
+}
+
+func (s *Server) handleSecurityAudit(w http.ResponseWriter, r *http.Request) {
+	var checks []securityCheck
+
+	// 1. Firewall (nftables) aktiv?
+	nftOut, err := exec.CommandContext(r.Context(), "nft", "list", "ruleset").Output()
+	nftStr := string(nftOut)
+	firewallActive := err == nil
+
+	if !firewallActive {
+		checks = append(checks, securityCheck{
+			Name:    "Firewall (nftables)",
+			Status:  "error",
+			Message: "nft konnte nicht ausgeführt werden — Firewall möglicherweise inaktiv",
+		})
+	} else if strings.Contains(nftStr, "policy drop") {
+		checks = append(checks, securityCheck{
+			Name:    "Firewall (nftables)",
+			Status:  "ok",
+			Message: "Aktiv — Input-Chain policy: drop (Whitelist-Modus)",
+		})
+	} else {
+		checks = append(checks, securityCheck{
+			Name:    "Firewall (nftables)",
+			Status:  "warning",
+			Message: "nftables aktiv, aber Input-Chain policy ist nicht 'drop'",
+		})
+	}
+
+	// 2. Port 3000 (Next.js) extern erreichbar?
+	if !firewallActive {
+		checks = append(checks, securityCheck{Name: "Port 3000 (Next.js)", Status: "error", Message: "Keine Firewall aktiv — Port möglicherweise extern erreichbar"})
+	} else if strings.Contains(nftStr, "dport 3000") {
+		checks = append(checks, securityCheck{Name: "Port 3000 (Next.js)", Status: "warning", Message: "Port 3000 explizit in Firewall-Regeln — prüfen ob gewollt"})
+	} else {
+		checks = append(checks, securityCheck{Name: "Port 3000 (Next.js)", Status: "ok", Message: "Blockiert (nicht in Whitelist)"})
+	}
+
+	// 3. Port 8080 (Go Backend) extern erreichbar?
+	if !firewallActive {
+		checks = append(checks, securityCheck{Name: "Port 8080 (Go Backend)", Status: "error", Message: "Keine Firewall aktiv — Port möglicherweise extern erreichbar"})
+	} else if strings.Contains(nftStr, "dport 8080") {
+		checks = append(checks, securityCheck{Name: "Port 8080 (Go Backend)", Status: "warning", Message: "Port 8080 explizit in Firewall-Regeln — prüfen ob gewollt"})
+	} else {
+		checks = append(checks, securityCheck{Name: "Port 8080 (Go Backend)", Status: "ok", Message: "Blockiert (nicht in Whitelist)"})
+	}
+
+	// 4. HTTPS aktiv?
+	if firewallActive && strings.Contains(nftStr, "dport 443") {
+		checks = append(checks, securityCheck{Name: "HTTPS (TLS)", Status: "ok", Message: "Port 443 in Firewall freigegeben"})
+	} else {
+		checks = append(checks, securityCheck{Name: "HTTPS (TLS)", Status: "warning", Message: "Kein HTTPS — Verbindungen unverschlüsselt (certbot empfohlen)"})
+	}
+
+	// 5. SSH PermitRootLogin + PasswordAuthentication
+	sshConf, err := os.ReadFile("/etc/ssh/sshd_config")
+	if err == nil {
+		lines := strings.Split(string(sshConf), "\n")
+		rootLogin := ""
+		passAuth := ""
+		for _, l := range lines {
+			tl := strings.ToLower(strings.TrimSpace(l))
+			if strings.HasPrefix(tl, "permitrootlogin") && !strings.HasPrefix(tl, "#") {
+				rootLogin = tl
+			}
+			if strings.HasPrefix(tl, "passwordauthentication") && !strings.HasPrefix(tl, "#") {
+				passAuth = tl
+			}
+		}
+		if strings.Contains(rootLogin, "no") || strings.Contains(rootLogin, "prohibit-password") {
+			checks = append(checks, securityCheck{Name: "SSH Root-Login", Status: "ok", Message: rootLogin})
+		} else if rootLogin == "" {
+			checks = append(checks, securityCheck{Name: "SSH Root-Login", Status: "warning", Message: "Nicht explizit gesetzt (Standard: prohibit-password)"})
+		} else {
+			checks = append(checks, securityCheck{Name: "SSH Root-Login", Status: "warning", Message: rootLogin + " — Passwort-Login für root möglich"})
+		}
+		if strings.Contains(passAuth, "no") {
+			checks = append(checks, securityCheck{Name: "SSH Passwort-Auth", Status: "ok", Message: "Nur Key-basierte Authentifizierung"})
+		} else if passAuth == "" {
+			checks = append(checks, securityCheck{Name: "SSH Passwort-Auth", Status: "warning", Message: "Nicht explizit deaktiviert — SSH-Keys empfohlen"})
+		} else {
+			checks = append(checks, securityCheck{Name: "SSH Passwort-Auth", Status: "warning", Message: passAuth + " — Brute-Force-Risiko"})
+		}
+	} else {
+		checks = append(checks, securityCheck{Name: "SSH Konfiguration", Status: "warning", Message: "/etc/ssh/sshd_config nicht lesbar"})
+	}
+
+	// 6. Fail2ban
+	f2bOut, err := exec.CommandContext(r.Context(), "systemctl", "is-active", "fail2ban").Output()
+	if err == nil && strings.TrimSpace(string(f2bOut)) == "active" {
+		checks = append(checks, securityCheck{Name: "Fail2ban", Status: "ok", Message: "Aktiv"})
+	} else {
+		checks = append(checks, securityCheck{Name: "Fail2ban", Status: "warning", Message: "Nicht aktiv — kein Brute-Force-Schutz (apt install fail2ban)"})
+	}
+
+	writeJSON(w, http.StatusOK, map[string]interface{}{
+		"checks": checks,
+		"run_at": time.Now().UTC().Format(time.RFC3339),
+	})
+}