feat: add debian12 scripts

- nftables_is_enabled.sh 		-> 4.2.9
- nftables_has_table.sh 		-> 4.2.4
- nftables_has_base_chains.sh 		-> 4.2.5
- nftables_rules_permanent.sh		-> 4.2.10
- nftables_default_deniy_policy.sh	-> 4.2.8

bin/hardening/nftables_default_deny_policy.sh

@@ -0,0 +1,89 @@
+#!/bin/bash
+
+# run-shellcheck
+#
+# CIS Debian Hardening
+#
+
+#
+# Ensure nftables default deny firewall policy (Manual)
+#
+
+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 default deny firewall policy "
+
+# This function will be called if the script status is on enabled / audit mode
+audit() {
+    INPUT_CHAIN_DROP=1
+    OUTPUT_CHAIN_DROP=1
+    FORWARD_CHAIN_DROP=1
+
+    if $SUDO_CMD nft list ruleset 2>/dev/null | grep "hook input.*policy drop"; then
+        INPUT_CHAIN_DROP=0
+        ok "nft base 'input' chain has 'drop' has default policy"
+    else
+        crit "nft base 'input' chain does not have 'drop' has default policy"
+    fi
+
+    if $SUDO_CMD nft list ruleset 2>/dev/null | grep 'hook output.*policy drop'; then
+        OUTPUT_CHAIN_DROP=0
+        ok "nft base 'output' chain has 'drop' has default policy"
+    else
+        crit "nft base 'output' chain does not have 'drop' has default policy"
+    fi
+
+    if $SUDO_CMD nft list ruleset 2>/dev/null | grep 'hook forward.*policy drop'; then
+        FORWARD_CHAIN_DROP=0
+        ok "nft base 'forward' chain has 'drop' has default policy"
+    else
+        crit "nft base 'forward' chain does not have 'drop' has default policy"
+    fi
+}
+
+# This function will be called if the script status is on enabled mode
+apply() {
+    audit
+    if [ "$INPUT_CHAIN_DROP" -ne 0 ]; then
+        info "Please review your default 'input' policy. We wont apply it for you to avoid cutting the branch you are sitting on"
+    fi
+
+    if [ "$OUTPUT_CHAIN_DROP" -ne 0 ]; then
+        info "Please review your default 'output' policy. We wont apply it for you to avoid cutting the branch you are sitting on"
+    fi
+
+    if [ "$FORWARD_CHAIN_DROP" -ne 0 ]; then
+        info "Please review your default 'forward' policy. We wont apply it for you to avoid cutting the branch you are sitting on"
+    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