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linux-scripts/install-fail2ban.sh
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#!/bin/bash
################################################################################
# Script Name: install-fail2ban.sh
# Version: 1.0
# Description: Automated Fail2ban installation with multi-jail configuration,
# custom ban actions, allowlists, Prometheus metrics integration,
# and service auto-detection for Debian/Ubuntu and RHEL/Rocky/Alma
#
# Author: Phil Connor
# Contact: contact@mylinux.work
# Website: https://mylinux.work
# License: MIT
#
# Usage:
# sudo ./install-fail2ban.sh
# sudo ./install-fail2ban.sh --jails "sshd,nginx-http-auth,postfix"
# sudo ./install-fail2ban.sh --allowlist "10.0.0.0/8,192.168.1.0/24"
# sudo ./install-fail2ban.sh --ban-action nftables --bantime 3600
# sudo ./install-fail2ban.sh --dry-run
# sudo ./install-fail2ban.sh --uninstall
#
################################################################################
set -euo pipefail
# ============================================================================
# DEFAULTS
# ============================================================================
readonly VERSION="1.0"
readonly SCRIPT_NAME="${0##*/}"
readonly LOG_FILE="/var/log/fail2ban-install.log"
JAILS=""
ALLOWLIST="127.0.0.1/8 ::1"
BAN_ACTION="auto"
BANTIME="3600"
FINDTIME="600"
MAXRETRY="5"
BACKEND="auto"
DRY_RUN=false
UNINSTALL=false
PROMETHEUS=false
RECIDIVE=true
# OS detection
OS_ID=""
OS_VERSION=""
PKG_MGR=""
# Colors
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
CYAN='\033[0;36m'
NC='\033[0m'
# ============================================================================
# HELPER FUNCTIONS
# ============================================================================
log_info() { echo -e "${GREEN}[INFO]${NC} $*"; echo "[INFO] $(date '+%Y-%m-%d %H:%M:%S') $*" >> "$LOG_FILE" 2>/dev/null || true; }
log_warn() { echo -e "${YELLOW}[WARN]${NC} $*"; echo "[WARN] $(date '+%Y-%m-%d %H:%M:%S') $*" >> "$LOG_FILE" 2>/dev/null || true; }
log_error() { echo -e "${RED}[ERROR]${NC} $*" >&2; echo "[ERROR] $(date '+%Y-%m-%d %H:%M:%S') $*" >> "$LOG_FILE" 2>/dev/null || true; }
log_step() { echo -e "${CYAN}[STEP]${NC} $*"; echo "[STEP] $(date '+%Y-%m-%d %H:%M:%S') $*" >> "$LOG_FILE" 2>/dev/null || true; }
show_usage() {
cat <<EOF
Usage: sudo $SCRIPT_NAME [OPTIONS]
Installs and configures Fail2ban with multi-jail support.
OPTIONS:
--jails LIST Comma-separated jails (default: auto-detect services)
--allowlist IPS Space or comma-separated trusted IPs/CIDRs to ignore
--ban-action TYPE Ban action: iptables, nftables, or auto (default: auto)
--bantime SECS Ban duration in seconds (default: 3600)
--findtime SECS Window for counting failures (default: 600)
--maxretry NUM Max failures before ban (default: 5)
--no-recidive Disable the recidive jail for repeat offenders
--prometheus Enable Prometheus metrics via fail2ban-exporter
--dry-run Show what would be done without making changes
--uninstall Remove Fail2ban and configuration
-h, --help Show this help message
SUPPORTED JAILS:
sshd SSH brute force (always enabled)
nginx-http-auth Nginx HTTP basic auth failures
nginx-botsearch Nginx bot/scanner blocking
nginx-limit-req Nginx rate limit violations
apache-auth Apache authentication failures
apache-badbots Apache bad bot blocking
postfix Postfix SMTP auth failures
dovecot Dovecot IMAP/POP3 auth failures
mysqld-auth MySQL/MariaDB auth failures
named-refused BIND DNS refused queries
recidive Repeat offender escalation
EXAMPLES:
# Auto-detect and install
sudo $SCRIPT_NAME
# Specific jails with custom settings
sudo $SCRIPT_NAME --jails "sshd,nginx-http-auth,postfix" --bantime 7200
# With allowlist and nftables
sudo $SCRIPT_NAME --allowlist "10.0.0.0/8" --ban-action nftables
EOF
exit 0
}
parse_args() {
while [[ $# -gt 0 ]]; do
case "$1" in
--jails) JAILS="$2"; shift 2 ;;
--allowlist) ALLOWLIST="$ALLOWLIST ${2//,/ }"; shift 2 ;;
--ban-action) BAN_ACTION="$2"; shift 2 ;;
--bantime) BANTIME="$2"; shift 2 ;;
--findtime) FINDTIME="$2"; shift 2 ;;
--maxretry) MAXRETRY="$2"; shift 2 ;;
--no-recidive) RECIDIVE=false; shift ;;
--prometheus) PROMETHEUS=true; shift ;;
--dry-run) DRY_RUN=true; shift ;;
--uninstall) UNINSTALL=true; shift ;;
-h|--help) show_usage ;;
*) log_error "Unknown option: $1"; show_usage ;;
esac
done
}
check_root() {
if [[ $EUID -ne 0 ]]; then
log_error "This script must be run as root (sudo)"
exit 1
fi
}
# ============================================================================
# OS DETECTION
# ============================================================================
detect_os() {
if [ -f /etc/os-release ]; then
. /etc/os-release
OS_ID="${ID}"
OS_VERSION="${VERSION_ID}"
else
log_error "Cannot detect OS — /etc/os-release not found"
exit 1
fi
case "$OS_ID" in
ubuntu|debian)
PKG_MGR="apt"
;;
rhel|rocky|almalinux|centos|fedora)
PKG_MGR="dnf"
if ! command -v dnf &>/dev/null; then
PKG_MGR="yum"
fi
;;
*)
log_error "Unsupported OS: $OS_ID"
exit 1
;;
esac
log_info "Detected OS: $OS_ID $OS_VERSION (package manager: $PKG_MGR)"
}
# ============================================================================
# SERVICE DETECTION
# ============================================================================
detect_services() {
if [ -n "$JAILS" ]; then
log_info "Using specified jails: $JAILS"
return
fi
log_step "Auto-detecting services for jail configuration..."
local detected=()
# SSH is always enabled
detected+=("sshd")
# Nginx
if systemctl is-active --quiet nginx 2>/dev/null || [ -f /etc/nginx/nginx.conf ]; then
detected+=("nginx-http-auth")
detected+=("nginx-botsearch")
log_info " Detected: nginx"
fi
# Apache
if systemctl is-active --quiet httpd 2>/dev/null || systemctl is-active --quiet apache2 2>/dev/null; then
detected+=("apache-auth")
detected+=("apache-badbots")
log_info " Detected: apache"
fi
# Postfix
if systemctl is-active --quiet postfix 2>/dev/null; then
detected+=("postfix")
log_info " Detected: postfix"
fi
# Dovecot
if systemctl is-active --quiet dovecot 2>/dev/null; then
detected+=("dovecot")
log_info " Detected: dovecot"
fi
# MySQL/MariaDB
if systemctl is-active --quiet mysqld 2>/dev/null || systemctl is-active --quiet mariadb 2>/dev/null; then
detected+=("mysqld-auth")
log_info " Detected: mysql/mariadb"
fi
# BIND
if systemctl is-active --quiet named 2>/dev/null || systemctl is-active --quiet bind9 2>/dev/null; then
detected+=("named-refused")
log_info " Detected: bind/named"
fi
JAILS=$(IFS=','; echo "${detected[*]}")
log_info "Auto-detected jails: $JAILS"
}
# ============================================================================
# BAN ACTION DETECTION
# ============================================================================
detect_ban_action() {
if [ "$BAN_ACTION" != "auto" ]; then
log_info "Using specified ban action: $BAN_ACTION"
return
fi
if command -v nft &>/dev/null && nft list ruleset &>/dev/null; then
BAN_ACTION="nftables-multiport"
log_info "Detected nftables — using nftables-multiport action"
elif command -v iptables &>/dev/null; then
BAN_ACTION="iptables-multiport"
log_info "Detected iptables — using iptables-multiport action"
else
BAN_ACTION="iptables-multiport"
log_warn "No firewall detected — defaulting to iptables-multiport"
fi
}
# ============================================================================
# INSTALLATION
# ============================================================================
install_fail2ban() {
log_step "Installing Fail2ban..."
if $DRY_RUN; then
log_info "[DRY RUN] Would install fail2ban via $PKG_MGR"
return
fi
case "$PKG_MGR" in
apt)
apt-get update -qq
apt-get install -y -qq fail2ban
;;
dnf|yum)
$PKG_MGR install -y -q epel-release 2>/dev/null || true
$PKG_MGR install -y -q fail2ban fail2ban-firewalld 2>/dev/null || \
$PKG_MGR install -y -q fail2ban
;;
esac
log_info "Fail2ban installed successfully"
}
# ============================================================================
# CONFIGURATION
# ============================================================================
configure_fail2ban() {
log_step "Configuring Fail2ban..."
local jail_local="/etc/fail2ban/jail.local"
if $DRY_RUN; then
log_info "[DRY RUN] Would write configuration to $jail_local"
show_config
return
fi
# Backup existing config
if [ -f "$jail_local" ]; then
cp "$jail_local" "${jail_local}.bak.$(date +%s)"
log_info "Backed up existing $jail_local"
fi
# Write jail.local
cat > "$jail_local" <<JAILEOF
# Fail2ban configuration — generated by $SCRIPT_NAME v$VERSION
# $(date)
[DEFAULT]
bantime = $BANTIME
findtime = $FINDTIME
maxretry = $MAXRETRY
banaction = $BAN_ACTION
banaction_allports = $BAN_ACTION
backend = $BACKEND
ignoreip = $ALLOWLIST
# Send alerts (uncomment and configure)
# destemail = admin@example.com
# sender = fail2ban@example.com
# mta = sendmail
# action = %(action_mwl)s
JAILEOF
# Generate jail sections
IFS=',' read -ra JAIL_ARRAY <<< "$JAILS"
for jail in "${JAIL_ARRAY[@]}"; do
jail=$(echo "$jail" | xargs) # trim whitespace
write_jail_config "$jail" >> "$jail_local"
done
# Recidive jail
if $RECIDIVE; then
cat >> "$jail_local" <<'RECIDIVEEOF'
[recidive]
enabled = true
logpath = /var/log/fail2ban.log
bantime = 604800
findtime = 86400
maxretry = 3
RECIDIVEEOF
log_info "Recidive jail enabled (repeat offenders banned for 7 days)"
fi
log_info "Configuration written to $jail_local"
}
write_jail_config() {
local jail="$1"
case "$jail" in
sshd)
cat <<'EOF'
[sshd]
enabled = true
port = ssh
logpath = %(sshd_log)s
maxretry = 5
EOF
;;
nginx-http-auth)
cat <<'EOF'
[nginx-http-auth]
enabled = true
port = http,https
logpath = /var/log/nginx/error.log
maxretry = 5
EOF
;;
nginx-botsearch)
cat <<'EOF'
[nginx-botsearch]
enabled = true
port = http,https
logpath = /var/log/nginx/access.log
maxretry = 2
EOF
;;
nginx-limit-req)
cat <<'EOF'
[nginx-limit-req]
enabled = true
port = http,https
logpath = /var/log/nginx/error.log
maxretry = 5
EOF
;;
apache-auth)
cat <<'EOF'
[apache-auth]
enabled = true
port = http,https
logpath = %(apache_error_log)s
maxretry = 5
EOF
;;
apache-badbots)
cat <<'EOF'
[apache-badbots]
enabled = true
port = http,https
logpath = %(apache_access_log)s
maxretry = 2
bantime = 86400
EOF
;;
postfix)
cat <<'EOF'
[postfix]
enabled = true
port = smtp,465,submission
logpath = /var/log/mail.log
maxretry = 5
EOF
;;
dovecot)
cat <<'EOF'
[dovecot]
enabled = true
port = pop3,pop3s,imap,imaps
logpath = /var/log/mail.log
maxretry = 5
EOF
;;
mysqld-auth)
cat <<'EOF'
[mysqld-auth]
enabled = true
port = 3306
logpath = /var/log/mysql/error.log
maxretry = 5
EOF
;;
named-refused)
cat <<'EOF'
[named-refused]
enabled = true
port = domain,953
logpath = /var/log/named/security.log
maxretry = 5
EOF
;;
*)
log_warn "Unknown jail: $jail — skipping"
;;
esac
}
show_config() {
echo ""
echo "=== Generated Configuration ==="
echo "[DEFAULT]"
echo "bantime = $BANTIME"
echo "findtime = $FINDTIME"
echo "maxretry = $MAXRETRY"
echo "banaction = $BAN_ACTION"
echo "ignoreip = $ALLOWLIST"
echo ""
IFS=',' read -ra JAIL_ARRAY <<< "$JAILS"
for jail in "${JAIL_ARRAY[@]}"; do
jail=$(echo "$jail" | xargs)
echo "[$jail] = enabled"
done
if $RECIDIVE; then
echo "[recidive] = enabled (7-day ban for repeat offenders)"
fi
echo "================================"
}
# ============================================================================
# PROMETHEUS INTEGRATION
# ============================================================================
setup_prometheus() {
if ! $PROMETHEUS; then
return
fi
log_step "Setting up Prometheus metrics integration..."
if $DRY_RUN; then
log_info "[DRY RUN] Would download fail2ban-exporter.sh"
return
fi
if [ -f /usr/local/bin/fail2ban-exporter.sh ]; then
log_info "fail2ban-exporter.sh already exists"
return
fi
local exporter_url="https://mylinux.work/downloads/fail2ban-exporter.sh"
if curl -fsSL "$exporter_url" -o /usr/local/bin/fail2ban-exporter.sh 2>/dev/null; then
chmod +x /usr/local/bin/fail2ban-exporter.sh
log_info "Downloaded fail2ban-exporter.sh"
# Add cron job
if ! crontab -l 2>/dev/null | grep -q "fail2ban-exporter"; then
(crontab -l 2>/dev/null; echo "*/2 * * * * /usr/local/bin/fail2ban-exporter.sh --textfile 2>/dev/null") | crontab -
log_info "Added cron job for fail2ban-exporter"
fi
else
log_warn "Could not download fail2ban-exporter.sh — configure manually"
fi
}
# ============================================================================
# SERVICE MANAGEMENT
# ============================================================================
start_fail2ban() {
log_step "Starting Fail2ban service..."
if $DRY_RUN; then
log_info "[DRY RUN] Would enable and start fail2ban"
return
fi
systemctl enable fail2ban
systemctl restart fail2ban
sleep 2
if systemctl is-active --quiet fail2ban; then
log_info "Fail2ban is running"
else
log_error "Fail2ban failed to start — check journalctl -u fail2ban"
exit 1
fi
}
# ============================================================================
# VERIFICATION
# ============================================================================
verify_installation() {
log_step "Verifying installation..."
if $DRY_RUN; then
log_info "[DRY RUN] Would verify installation"
return
fi
echo ""
echo "=== Fail2ban Status ==="
fail2ban-client status
echo ""
IFS=',' read -ra JAIL_ARRAY <<< "$JAILS"
for jail in "${JAIL_ARRAY[@]}"; do
jail=$(echo "$jail" | xargs)
echo "--- $jail ---"
fail2ban-client status "$jail" 2>/dev/null || echo " (jail not active — check logs)"
echo ""
done
if $RECIDIVE; then
echo "--- recidive ---"
fail2ban-client status recidive 2>/dev/null || echo " (recidive not active)"
echo ""
fi
echo "=== Configuration ==="
echo "Ban action: $BAN_ACTION"
echo "Ban time: ${BANTIME}s ($(( BANTIME / 60 )) minutes)"
echo "Find time: ${FINDTIME}s ($(( FINDTIME / 60 )) minutes)"
echo "Max retry: $MAXRETRY"
echo "Ignore list: $ALLOWLIST"
echo ""
log_info "Installation complete. Logs: $LOG_FILE"
}
# ============================================================================
# UNINSTALL
# ============================================================================
uninstall_fail2ban() {
log_step "Uninstalling Fail2ban..."
if $DRY_RUN; then
log_info "[DRY RUN] Would stop and remove fail2ban"
return
fi
systemctl stop fail2ban 2>/dev/null || true
systemctl disable fail2ban 2>/dev/null || true
case "$PKG_MGR" in
apt)
apt-get purge -y -qq fail2ban
apt-get autoremove -y -qq
;;
dnf|yum)
$PKG_MGR remove -y -q fail2ban
;;
esac
# Clean up config
if [ -d /etc/fail2ban ]; then
log_info "Configuration directory /etc/fail2ban preserved — remove manually if desired"
fi
log_info "Fail2ban uninstalled"
exit 0
}
# ============================================================================
# MAIN
# ============================================================================
main() {
parse_args "$@"
echo ""
echo "============================================"
echo " Fail2ban Install Script v${VERSION}"
echo " https://mylinux.work"
echo "============================================"
echo ""
check_root
detect_os
if $UNINSTALL; then
uninstall_fail2ban
fi
detect_services
detect_ban_action
install_fail2ban
configure_fail2ban
setup_prometheus
start_fail2ban
verify_installation
}
main "$@"
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