debian-cis/bin/hardening/2.2.15_mta_localhost.sh

#!/bin/bash

# run-shellcheck
#
# CIS Debian Hardening
#

#
# 2.2.15 Ensure Mail Transfer Agent is configured for Local-Only Mode (Scored)
#

set -e # One error, it's over
set -u # One variable unset, it's over

# shellcheck disable=2034
HARDENING_LEVEL=3
# shellcheck disable=2034
DESCRIPTION="Configure Mail Transfert Agent for Local-Only Mode."
# shellcheck disable=2034
HARDENING_EXCEPTION=mail

# This function will be called if the script status is on enabled / audit mode
audit() {
    is_pkg_installed net-tools
    if [ "$FNRET" != 0 ]; then
        warn "netstat not installed, cannot execute check"
        exit 2
    else
        info "Checking netport ports opened"
        RESULT=$($SUDO_CMD netstat -an | grep LIST | grep ":25[[:space:]]") || :
        RESULT=${RESULT:-}
        debug "Result is $RESULT"
        if [ -z "$RESULT" ]; then
            ok "Nothing listens on 25 port, probably unix socket configured"
        else
            info "Checking $RESULT"
            if grep -q "127.0.0.1" <<<"$RESULT"; then
                ok "MTA is configured to localhost only"
            else
                crit "MTA listens worldwide"
            fi
        fi
    fi
}

# This function will be called if the script status is on enabled mode
apply() {
    is_pkg_installed net-tools
    if [ "$FNRET" != 0 ]; then
        warn "netstat not installed, cannot execute check"
        exit 2
    else
        info "Checking netport ports opened"
        RESULT=$(netstat -an | grep LIST | grep ":25[[:space:]]") || :
        RESULT=${RESULT:-}
        debug "Result is $RESULT"
        if [ -z "$RESULT" ]; then
            ok "Nothing listens on 25 port, probably unix socket configured"
        else
            info "Checking $RESULT"
            if grep -q "127.0.0.1" <<<"$RESULT"; then
                ok "MTA is configured to localhost only"
            else
                warn "MTA listens worldwide, correct this considering your MTA"
            fi
        fi
    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_ROOT_DIR" ]; then
    echo "There is no /etc/default/cis-hardening file nor cis-hardening directory in current environment."
    echo "Cannot source CIS_ROOT_DIR variable, aborting."
    exit 128
fi

# Main function, will call the proper functions given the configuration (audit, enabled, disabled)
if [ -r "$CIS_ROOT_DIR"/lib/main.sh ]; then
    # shellcheck source=../../lib/main.sh
    . "$CIS_ROOT_DIR"/lib/main.sh
else
    echo "Cannot find main.sh, have you correctly defined your root directory? Current value is $CIS_ROOT_DIR in /etc/default/cis-hardening"
    exit 128
fi