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#!/bin/bash
set -euo pipefail
SCRIPT_NAME="gateway-apply-rules"
LOG_FACILITY="local0.info"
# Ansible template variables - configured at deployment time
GATEWAY_SUBNET_V4="{{ gateway_local_ipv4_subnet }}"
GATEWAY_SUBNET_V6="{{ gateway_local_ipv6_subnet }}"
GATEWAY_INTERFACE="{{ gateway_router_interface }}"
log_message() {
echo "[$SCRIPT_NAME] $1" | logger -t "$SCRIPT_NAME" -p "$LOG_FACILITY"
echo "[$(date '+%Y-%m-%d %H:%M:%S')] $1"
}
detect_vpn_interfaces() {
ip link show | grep -E '^[0-9]+: wg.*:.*UP' | cut -d: -f2 | tr -d ' ' || true
}
clear_rules() {
log_message "Clearing existing gateway rules"
iptables -F FORWARD 2>/dev/null || true
iptables -t nat -D POSTROUTING -s "$GATEWAY_SUBNET_V4" -o wg+ -j MASQUERADE 2>/dev/null || true
iptables -t nat -D POSTROUTING -s "$GATEWAY_SUBNET_V4" -o "$GATEWAY_INTERFACE" -j MASQUERADE 2>/dev/null || true
iptables -D OUTPUT -o wg+ -j ACCEPT 2>/dev/null || true
iptables -D OUTPUT -o "$GATEWAY_INTERFACE" -j ACCEPT 2>/dev/null || true
if [ -n "$GATEWAY_SUBNET_V6" ]; then
ip6tables -F FORWARD 2>/dev/null || true
ip6tables -t nat -D POSTROUTING -s "$GATEWAY_SUBNET_V6" -o wg+ -j MASQUERADE 2>/dev/null || true
ip6tables -t nat -D POSTROUTING -s "$GATEWAY_SUBNET_V6" -o "$GATEWAY_INTERFACE" -j MASQUERADE 2>/dev/null || true
ip6tables -D OUTPUT -o wg+ -j ACCEPT 2>/dev/null || true
ip6tables -D OUTPUT -o "$GATEWAY_INTERFACE" -j ACCEPT 2>/dev/null || true
fi
}
apply_vpn_mode() {
local vpn_interfaces="$1"
log_message "Applying VPN mode rules for interfaces: $vpn_interfaces"
iptables -t nat -A POSTROUTING -s "$GATEWAY_SUBNET_V4" -o wg+ -j MASQUERADE
iptables -A OUTPUT -o wg+ -j ACCEPT
iptables -A FORWARD -s "$GATEWAY_SUBNET_V4" -o wg+ -j ACCEPT
iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
if [ -n "$GATEWAY_SUBNET_V6" ]; then
ip6tables -t nat -A POSTROUTING -s "$GATEWAY_SUBNET_V6" -o wg+ -j MASQUERADE
ip6tables -A OUTPUT -o wg+ -j ACCEPT
ip6tables -A FORWARD -s "$GATEWAY_SUBNET_V6" -o wg+ -j ACCEPT
ip6tables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
fi
log_message "VPN mode rules applied - traffic routed through VPN"
}
apply_direct_rules() {
log_message "Applying direct mode rules"
iptables -t nat -A POSTROUTING -s "$GATEWAY_SUBNET_V4" -o "$GATEWAY_INTERFACE" -j MASQUERADE
iptables -A OUTPUT -o "$GATEWAY_INTERFACE" -j ACCEPT
iptables -A FORWARD -s "$GATEWAY_SUBNET_V4" -o "$GATEWAY_INTERFACE" -j ACCEPT
iptables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
if [ -n "$GATEWAY_SUBNET_V6" ]; then
# No MASQUERADE for IPv6: LAN devices have public SLAAC addresses, native routing applies
ip6tables -A OUTPUT -o "$GATEWAY_INTERFACE" -j ACCEPT
ip6tables -A FORWARD -s "$GATEWAY_SUBNET_V6" -o "$GATEWAY_INTERFACE" -j ACCEPT
ip6tables -A FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
fi
log_message "Direct mode rules applied - normal routing active"
}
handle_vpn_mode() {
local vpn_interfaces
vpn_interfaces=$(detect_vpn_interfaces)
if [ -n "$vpn_interfaces" ]; then
clear_rules
apply_vpn_mode "$vpn_interfaces"
log_message "Switched to VPN mode"
else
log_message "No VPN interfaces found, ignoring VPN mode request"
fi
}
handle_direct_mode() {
local vpn_interfaces
vpn_interfaces=$(detect_vpn_interfaces)
if [ -z "$vpn_interfaces" ]; then
clear_rules
apply_direct_rules
log_message "Switched to direct mode"
else
log_message "VPN interfaces still active: $vpn_interfaces"
fi
}
main() {
local mode="$1"
case "$mode" in
"vpn")
handle_vpn_mode
;;
"direct")
handle_direct_mode
;;
*)
log_message "Unknown mode: $mode"
exit 1
;;
esac
}
trap 'log_message "Script failed with error on line $LINENO"' ERR
main "$@"
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