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

bin/hardening/ufw_default_deny.sh

@@ -0,0 +1,102 @@
+#!/bin/bash
+
+# run-shellcheck
+#
+# CIS Debian Hardening
+#
+
+#
+# Ensure ufw default deny firewall policy (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 ufw default deny firewall policy"
+UFW_DEFAULT_RULES_FILE="/etc/default/ufw"
+
+# This function will be called if the script status is on enabled / audit mode
+audit() {
+    UFW_INPUT_DEFAULT_VALID=1
+    UFW_OUTPUT_DEFAULT_VALID=1
+    UFW_FORWARD_DEFAULT_VALID=1
+
+    # ufw default rules are configured in /etc/default/ufw
+    # easier to parse than ufw output
+    local default_policy
+    default_policy=$(awk -F '=' '/^[^#]*DEFAULT_INPUT_POLICY/ {print $2}' "$UFW_DEFAULT_RULES_FILE" | sed 's/\"//g')
+    if [ "$default_policy" != "DROP" ]; then
+        crit "ufw default input policy is $default_policy instead of DROP"
+    else
+        ok "ufw default input policy is $default_policy"
+        UFW_INPUT_DEFAULT_VALID=0
+    fi
+
+    default_policy=$(awk -F '=' '/^[^#]*DEFAULT_OUTPUT_POLICY/ {print $2}' "$UFW_DEFAULT_RULES_FILE" | sed 's/\"//g')
+    if [ "$default_policy" != "DROP" ]; then
+        crit "ufw default output policy is $default_policy instead of DROP"
+    else
+        ok "ufw default output policy is $default_policy"
+        UFW_OUTPUT_DEFAULT_VALID=0
+    fi
+
+    default_policy=$(awk -F '=' '/^[^#]*DEFAULT_FORWARD_POLICY/ {print $2}' "$UFW_DEFAULT_RULES_FILE" | sed 's/\"//g')
+    if [ "$default_policy" != "DROP" ]; then
+        crit "ufw default forward policy is $default_policy instead of DROP"
+    else
+        ok "ufw default forward policy is $default_policy"
+        UFW_FORWARD_DEFAULT_VALID=0
+    fi
+
+    if [ "$UFW_INPUT_DEFAULT_VALID" -ne 0 ] || [ "$UFW_OUTPUT_DEFAULT_VALID" -ne 0 ] || [ "$UFW_FORWARD_DEFAULT_VALID" -ne 0 ]; then
+        warn "Applying the recommendation will change the default policies to DROP, make sure you have set up the required rules"
+    fi
+
+}
+
+# This function will be called if the script status is on enabled mode
+apply() {
+    if [ "$UFW_INPUT_DEFAULT_VALID" -ne 0 ]; then
+        info "changing default input policy to DROP"
+        ufw default deny incoming
+    fi
+
+    if [ "$UFW_OUTPUT_DEFAULT_VALID" -ne 0 ]; then
+        info "changing default output policy to DROP"
+        ufw default deny outgoing
+    fi
+
+    if [ "$UFW_FORWARD_DEFAULT_VALID" -ne 0 ]; then
+        info "changing default forward policy to DROP"
+        ufw default deny routed
+    fi
+
+}
+
+# This function will check config parameters required
+check_config() {
+    :
+}
+
+# Source Root Dir Parameter
+if [ -r /etc/default/cis-hardening ]; then
+    # shellcheck source=../../debian/default
+    . /etc/default/cis-hardening
+fi
+if [ -z "$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