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Adjust DDoS thresholds for production web servers

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Raised minimum thresholds to prevent false positives on busy websites:

Previous (too aggressive for web servers):
- Tier 4: >2 connections
- Tier 3: >3 connections
- Tier 2: >5 connections
- Tier 1: >8 connections
- Minimum: 2

New (production-safe):
- Tier 4: >3 connections (500+ total SYN)
- Tier 3: >4 connections (300-500 total)
- Tier 2: >6 connections (150-300 total)
- Tier 1: >10 connections (75-150 total)
- Minimum: 3

Rationale:
Web servers handle legitimate high traffic with brief SYN_RECV spikes.
Corporate NAT, mobile users, and APIs can cause 2-3 SYN_RECV legitimately.
Minimum of 3 prevents false positives while still catching distributed attacks.

Your 512-connection attack still triggers Tier 4 with threshold 3,
detecting 40+ attacking IPs while protecting legitimate traffic.
This commit is contained in:
cschantz
2025-12-24 20:07:25 -05:00
parent f4b3a2401c
commit 5fbed6ae4c
2 changed files with 26 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files
modules/security/live-attack-monitor.sh
+13 -13
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@@ -2315,32 +2315,32 @@ monitor_network_attacks() {
# Dynamic threshold based on attack severity + momentum:
# Tier 0: >20 connections (normal, focused attack)
# Tier 1: >8 connections (75-150 total, moderate DDoS)
# Tier 2: >5 connections (150-300 total, major DDoS)
# Tier 3: >3 connections (300-500 total, severe DDoS)
# Tier 4: >2 connections (500+ total, CRITICAL DDoS)
# Tier 1: >10 connections (75-150 total, moderate DDoS)
# Tier 2: >6 connections (150-300 total, major DDoS)
# Tier 3: >4 connections (300-500 total, severe DDoS)
# Tier 4: >3 connections (500+ total, CRITICAL DDoS)
local threshold=20
case "$attack_severity" in
4) threshold=2 ;; # Critical: Hyper-aggressive
3) threshold=3 ;; # Severe: Very aggressive
2) threshold=5 ;; # Major: Aggressive
1) threshold=8 ;; # Moderate: Balanced
4) threshold=3 ;; # Critical: Very aggressive (safe for production)
3) threshold=4 ;; # Severe: Aggressive
2) threshold=6 ;; # Major: Balanced
1) threshold=10 ;; # Moderate: Conservative
esac
# Attack momentum adaptation: Lower threshold if attack is growing
if [ "$attack_momentum" -eq 2 ] && [ "$threshold" -gt 2 ]; then
if [ "$attack_momentum" -eq 2 ] && [ "$threshold" -gt 3 ]; then
threshold=$((threshold - 2)) # Rapidly accelerating attack
elif [ "$attack_momentum" -eq 1 ] && [ "$threshold" -gt 2 ]; then
elif [ "$attack_momentum" -eq 1 ] && [ "$threshold" -gt 3 ]; then
threshold=$((threshold - 1)) # Accelerating attack
fi
# Coordinated attack bonus: Lower threshold by 1 (stacks with momentum)
if [ "$coordinated_attack" -eq 1 ] && [ "$threshold" -gt 2 ]; then
if [ "$coordinated_attack" -eq 1 ] && [ "$threshold" -gt 3 ]; then
threshold=$((threshold - 1))
fi
# Minimum threshold of 2 to prevent false positives
[ "$threshold" -lt 2 ] && threshold=2
# Minimum threshold of 3 to prevent false positives on busy web servers
[ "$threshold" -lt 3 ] && threshold=3
if [ "$count" -gt "$threshold" ]; then
# Only process once per detection window