Linux Monitor - Firewall Script

#!/bin/bash

# This resource is provided as a convenience for Level users. We cannot 
# guarantee it will work in all environments. Please test before deploying 
# to your production environment. We welcome contributions to our community 
# library

# Level Library
# https://level.io/library/script-linux-monitor-firewall

#!/bin/bash

# Initialize a flag to track if any firewall is active or configured
FIREWALL_ACTIVE=0

# Function to check UFW status
check_ufw() {
  if command -v ufw >/dev/null 2>&1; then
    echo "Checking UFW..."
    STATUS=$(ufw status)
    if [[ "$STATUS" == *"Status: active"* ]]; then
      echo "UFW is ENABLED."
      FIREWALL_ACTIVE=1
    else
      echo "UFW is DISABLED or not configured."
    fi
  fi
}

# Function to check iptables status
check_iptables() {
  if command -v iptables >/dev/null 2>&1; then
    echo "Checking iptables..."
    RULES=$(iptables -L | wc -l)
    if [ "$RULES" -gt 8 ]; then # Assuming base rule count is 8 for the default chains
      echo "iptables has rules set (may be ENABLED)."
      FIREWALL_ACTIVE=1
    else
      echo "iptables does not have many rules set (may be DISABLED or not configured)."
    fi
  fi
}

# Function to check nftables status
check_nftables() {
  if command -v nft >/dev/null 2>&1; then
    echo "Checking nftables..."
    TABLES=$(nft list tables | wc -l)
    if [ "$TABLES" -gt 0 ]; then
      echo "nftables has tables configured (may be ENABLED)."
      FIREWALL_ACTIVE=1
    else
      echo "nftables does not have any tables configured (may be DISABLED or not configured)."
    fi
  fi
}

# Run the firewall checks
echo "Checking firewall status..."
check_ufw
check_iptables
check_nftables

# If no firewall is active or configured, report an error and exit with 1
if [ $FIREWALL_ACTIVE -eq 0 ]; then
  echo "ERROR: No active or configured firewall detected."
  exit 1
else
  echo "SUCCESS: An active or configured firewall is detected."
  exit 0
fi