PROBLEM: Live monitor showed static CT_LIMIT="100" recommendation
- No analysis of actual site traffic
- No consideration of legitimate high-connection users
- Could block CDNs, bots, or legitimate traffic spikes
- No way to know what's safe for the specific server
SOLUTION: Created comprehensive CT_LIMIT optimizer script
NEW SCRIPT: modules/security/optimize-ct-limit.sh
WHAT IT DOES:
1. Analyzes Apache logs (last 24 hours by default)
- Parses all domain logs in /var/log/apache2/domlogs/
- Tracks max concurrent connections per IP per domain
- Identifies user agents and behavior patterns
2. Classifies IP behavior using bot-signatures.sh
- Legitimate bots (Googlebot, Bingbot, etc.)
- AI crawlers (GPT, Claude, etc.)
- CDNs (Cloudflare, Akamai, etc.)
- Normal users vs high-traffic users
- Potential scrapers
3. Analyzes current active connections
- Uses ss or netstat to check real-time connections
- Identifies current highest connection counts
4. Calculates statistics
- 95th percentile of legitimate user connections
- 99th percentile for headroom
- Max concurrent from single legitimate IP
- Separates bot/CDN traffic from user traffic
5. Provides 3 recommendations:
a) CONSERVATIVE (max_legit + 20) - For high-traffic sites
b) BALANCED (max_legit + 10) - Recommended for most ⭐
c) AGGRESSIVE (max_legit + 5) - Only during active attack
6. Whitelist recommendations
- Identifies bots/CDNs exceeding recommended limit
- Suggests specific IPs to whitelist in CSF
- Prevents blocking Googlebot, monitoring services, etc.
7. One-command application
- Backs up csf.conf automatically
- Updates CT_LIMIT to recommended value
- Enables SYNFLOOD protection
- Restarts CSF
- Provides monitoring command
EXAMPLE OUTPUT:
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Connection Analysis Summary:
Total unique IPs analyzed: 1,247
Legitimate users: 1,180
Bots/CDNs/Crawlers: 67
Legitimate User Connection Patterns:
Max concurrent from single IP: 45
95th percentile: 12 concurrent connections
99th percentile: 28 concurrent connections
Current Active Connections:
Highest right now: 8 connections from 1.2.3.4
Current CSF Configuration:
CT_LIMIT = 150
📊 RECOMMENDED CT_LIMIT VALUES
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
1. CONSERVATIVE: CT_LIMIT = 65
• Allows headroom for traffic spikes
• Won't block legitimate users
2. BALANCED: CT_LIMIT = 55 ⭐
• Based on 99th percentile + buffer
• Blocks most attack traffic
3. AGGRESSIVE: CT_LIMIT = 50
• Maximum DDoS protection
• May affect some legitimate users
⚠️ WHITELIST RECOMMENDATIONS
Found bots/crawlers with high connection counts:
• 66.249.72.38 (Googlebot) 82 connections
• 40.77.167.88 (Bingbot) 65 connections
• 157.55.39.183 (UptimeRobot) 48 connections
To whitelist: csf -a <IP>
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
INTEGRATION WITH LIVE MONITOR:
- Press 'c' during live monitoring to run optimizer
- Recommendation updates based on detected DDoS/SYN floods
- Quick Actions panel shows: "Press 'c' to run CT_LIMIT optimizer"
- Help screen updated with 'c' key
USAGE:
1. Standalone: modules/security/optimize-ct-limit.sh
2. From live monitor: Press 'c' during monitoring
3. With custom period: optimize-ct-limit.sh 48 (48 hours)
SAFETY:
- Automatic backup of csf.conf before changes
- Minimum thresholds (50/80/100) prevent too-aggressive limits
- Option to apply or just view recommendations
- Full report saved to /tmp for review
INTELLIGENCE:
- Uses actual traffic data, not guesses
- Accounts for legitimate high-connection sources
- Prevents blocking search engines and monitoring
- Adapts to each server's unique traffic patterns
FILES MODIFIED:
- modules/security/optimize-ct-limit.sh (NEW - 650 lines)
- modules/security/live-attack-monitor.sh
- Added 'c' key handler (line 1019-1024)
- Updated Quick Actions recommendation (line 438)
- Updated help screen (line 1045)
- Updated footer keys (line 457)
cschantz