Files
debian-cis/bin/hardening/nftables_loopback_is_configured.sh
damien cavagnini d171310d81 feat: add debian12 scripts
- nftables_loopback_is_configured.sh 	-> 4.2.6
- nftables_established_connections.sh 	-> 4.2.7
- iptables_flushed_with_nftables.sh 	-> 4.2.3
- ufw_loopback_is_configured.sh 	-> 4.1.4
- ufw_outbound_connection.sh 		-> 4.1.5
- ufw_default_deny.sh 			-> 4.1.7
- ufw_rules_them_all.sh 		-> 4.1.6
2025-08-22 15:43:48 +02:00

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#!/bin/bash
# run-shellcheck
#
# CIS Debian Hardening
#
#
# Ensure nftables loopback traffic is configured (Automated)
#
set -e # One error, it's over
set -u # One variable unset, it's over
# shellcheck disable=2034
HARDENING_LEVEL=2
# shellcheck disable=2034
DESCRIPTION="Ensure nftables loopback traffic is configured"
# This function will be called if the script status is on enabled / audit mode
audit() {
NFTABLES_LOOPBACK=1
NFTABLES_LOOPBACK_DROP=1
NFTABLES_IPV6_LOOPBACK_DROP=1
if nft list ruleset 2>/dev/null | awk '/hook input/,/}/' | grep 'iif "lo" accept'; then
NFTABLES_LOOPBACK=0
ok "loopback is configured for nftables"
else
crit "loopback is not configured for nftables"
fi
if nft list ruleset 2>/dev/null | awk '/hook input/,/}/' | grep "ip saddr 127.0.0.1.*drop"; then
NFTABLES_LOOPBACK_DROP=0
ok "nftables input loopack traffic is dropped"
else
crit "nftables input loopack traffic is not dropped"
fi
is_ipv6_enabled
if [ "$FNRET" -eq 0 ]; then
if nft list ruleset 2>/dev/null | awk '/hook input/,/}/' | grep "ip6 saddr ::1.*drop"; then
NFTABLES_IPV6_LOOPBACK_DROP=0
ok "nftables input loopack traffic is dropped"
else
crit "nftables input loopack traffic is not dropped"
fi
fi
}
# This function will be called if the script status is on enabled mode
apply() {
if [ "$NFTABLES_LOOPBACK" -ne 0 ]; then
info "adding nftables loopback configuration"
nft add rule inet filter input iif lo accept
fi
if [ "$NFTABLES_LOOPBACK_DROP" -ne 0 ]; then
info "adding nftables loopback drop configuration"
nft create rule inet filter input ip saddr 127.0.0.0/8 counter drop
fi
is_ipv6_enabled
if [ "$FNRET" -eq 0 ] && [ "$NFTABLES_IPV6_LOOPBACK_DROP" -ne 0 ]; then
info "adding nftables ipv6 loopback drop configuration"
nft add rule inet filter input ip6 saddr ::1 counter drop
fi
}
# This function will check config parameters required
check_config() {
:
}
# Source Root Dir Parameter
if [ -r /etc/default/cis-hardening ]; then
# shellcheck source=../../debian/default
. /etc/default/cis-hardening
fi
if [ -z "$CIS_LIB_DIR" ]; then
echo "There is no /etc/default/cis-hardening file nor cis-hardening directory in current environment."
echo "Cannot source CIS_LIB_DIR variable, aborting."
exit 128
fi
# Main function, will call the proper functions given the configuration (audit, enabled, disabled)
if [ -r "${CIS_LIB_DIR}"/main.sh ]; then
# shellcheck source=../../lib/main.sh
. "${CIS_LIB_DIR}"/main.sh
else
echo "Cannot find main.sh, have you correctly defined your root directory? Current value is $CIS_LIB_DIR in /etc/default/cis-hardening"
exit 128
fi