#!/bin/sh

#################################################################################
#
#   Lynis
# ------------------
#
# Copyright 2007-2013, Michael Boelen
# Copyright 2013-2016, CISOfy
#
# Website  : https://cisofy.com
# Blog     : http://linux-audit.com
# GitHub   : https://github.com/CISOfy/lynis
#
# Lynis comes with ABSOLUTELY NO WARRANTY. This is free software, and you are
# welcome to redistribute it under the terms of the GNU General Public License.
# See LICENSE file for usage of this software.
#
#################################################################################
#
# Firewalls
#
#################################################################################
#
    InsertSection "Software: firewalls"
#
#################################################################################
#
    IPTABLES_ACTIVE=0
    IPTABLES_INKERNEL_ACTIVE=0
    IPTABLES_MODULE_ACTIVE=0
    FIREWALL_ACTIVE=0
    FIREWALL_EMPTY_RULESET=0
    FIREWALL_SOFTWARE=""
    NFTABLES_ACTIVE=0
#
#################################################################################
#
    # Test        : FIRE-4502
    # Description : Check iptables kernel module
    Register --test-no FIRE-4502 --os Linux --weight L --network NO --category security --description "Check iptables kernel module"
    if [ ${SKIPTEST} -eq 0 ]; then
        FIND=$(${LSMODBINARY} | ${AWKBINARY} '{ print $1 }' | ${GREPBINARY} "^ip*_tables")
        if [ ! -z "${FIND}" ]; then
            FIREWALL_ACTIVE=1
            FIREWALL_SOFTWARE="iptables"
            IPTABLES_ACTIVE=1
            IPTABLES_MODULE_ACTIVE=1
            Display --indent 2 --text "- Checking iptables kernel module" --result "${STATUS_FOUND}" --color GREEN
            LogText "Result: Found iptables in loaded kernel modules"
            for I in ${FIND}; do
                LogText "Found module: ${I}"
            done
        else
            Display --indent 2 --text "- Checking iptables kernel module" --result "${STATUS_NOT_FOUND}" --color WHITE

            # If we can't find an active module, try to find the Linux configuration file and check that
            if [ -f /proc/config.gz ]; then
                LINUXCONFIGFILE="/proc/config.gz"; tCATCMD="zcat";
            fi
            sLINUXCONFIGFILE="/boot/config-$(uname -r)"
            if [ -f ${sLINUXCONFIGFILE} ]; then
                LINUXCONFIGFILE=${sLINUXCONFIGFILE}; tCATCMD="cat";
            fi

            # If we have a kernel configuration file, use it for testing
            # Do not perform test if we already found it in kernel module list, to avoid triggered it in the upcoming
            # tests, when using iptables --list
            if [ ! "${LINUXCONFIGFILE}" = "" ]; then
                if [ -f ${LINUXCONFIGFILE} -a ${IPTABLES_MODULE_ACTIVE} -eq 0 ]; then
                    LogText "Result: found kernel configuration file (${LINUXCONFIGFILE})"
                    FIND=$(${tCATCMD} ${LINUXCONFIGFILE} | ${GREPBINARY} -v '^#' | ${GREPBINARY} "CONFIG_IP_NF_IPTABLES" | head -n 1)
                    if [ ! -z "${FIND}" ]; then
                        HAVEMOD=$(echo ${FIND} | ${CUTBINARY} -d '=' -f2)
                        # Do not use iptables if it's compiled as a module (=m), since we already tested for it in the
                        # active list.
                        if [ "${HAVEMOD}" = "y" ]; then
                                LogText "Result: iptables available as a module in the configuration"
                                IPTABLES_ACTIVE=1
                                IPTABLES_INKERNEL_ACTIVE=1
                                FIREWALL_ACTIVE=1
                                FIREWALL_SOFTWARE="iptables"
                                Display --indent 2 --text "- Checking iptables in config file" --result "${STATUS_FOUND}" --color GREEN
                        else
                            LogText "Result: no iptables found in Linux kernel config file"
                        fi
                    else
                        LogText "Result: no Linux configuration file found"
                        Display --indent 2 --text "- Checking iptables in config file" --result "${STATUS_NOT_FOUND}" --color WHITE
                    fi
                fi
            fi
        fi
        if [ ${IPTABLES_ACTIVE} -eq 1 ]; then Report "firewall_software[]=iptables"; fi
    fi
#
#################################################################################
#
    # Test        : FIRE-4508
    # Description : Check iptables chain policies
    # Notes       : Suggestions are currently disabled, until related page and documentation is available
    if [ ! "${IPTABLESBINARY}" = "" -a ${IPTABLES_ACTIVE} -eq 1 ]; then PREQS_MET="YES"; else PREQS_MET="NO"; fi
    Register --test-no FIRE-4508 --preqs-met ${PREQS_MET} --os Linux --weight L --network NO --root-only YES --category security --description "Check used policies of iptables chains"
    if [ ${SKIPTEST} -eq 0 ]; then
        Display --indent 4 --text "- Checking iptables policies of chains" --result "${STATUS_FOUND}" --color GREEN
        TABLES="filter"
        for TABLE in ${TABLES}; do
            LogText "Test: gathering information from table ${TABLE}"
            FIND="$FIND""\n"`${IPTABLESBINARY} -t ${TABLE} --numeric --list | ${EGREPBINARY}  -z -o -w  '[A-Z]+' | ${AWKBINARY} -v t=${TABLE} 'NR%2 {printf "%s %s ",t, $0 ; next;}1'`
        done

        echo "${FIND}" | while read line; do
            table=$(echo ${line} | ${AWKBINARY} '{ print $1 }')
            chainname=$(echo ${line} | ${AWKBINARY} '{ print $2 }')
            policy=$(echo ${line} | ${AWKBINARY} '{ print $3 }')
            LogText "Result: iptables  ${table}  -- ${chainname} policy is ${policy}."
            LogText "Result: ${policy}"

            if [ "${TABLE}" = "filter" ]; then
                if [ "${chainname}" = "INPUT" ]; then
                    case ${policy} in
                        "ACCEPT")
                             LogText "Result: Found ACCEPT for ${chainname} (table: ${table})"
                             Display --indent 6 --text "- Checking chain ${chainname} (table: ${table}) policy" --result ${policy} --color YELLOW
                             #ReportSuggestion ${TEST_NO} "Consider settings default chain policy to DROP (iptables chain ${chainname}, table: ${table})"
                             AddHP 1 3
                             ;;
                         "DROP")
                             LogText "Result: Found DROP for ${chainname} (table: ${table})"
                             Display --indent 6 --text "- Checking chain ${chainname} (table: ${table}) policy" --result ${policy} --color GREEN
                             AddHP 3 3
                             ;;
                         *)
                             Display --indent 6 --text "- Checking chain ${chainname} (table: ${table}) policy" --result ${policy} --color YELLOW
                             LogText "Result: Unknown policy: ${policy}"
                             #ReportSuggestion ${TEST_NO} "Check iptables ${chainname} (table: ${table}) chain policy"
                             ;;
                    esac
                fi
            fi
        done
    fi
#
#################################################################################
#
    # Test        : FIRE-4512
    # Description : Check iptables for empty ruleset (should have at least 10 or more rules)
    if [ ! "${IPTABLESBINARY}" = "" -a ${IPTABLES_ACTIVE} -eq 1 ]; then PREQS_MET="YES"; else PREQS_MET="NO"; fi
    Register --test-no FIRE-4512 --preqs-met ${PREQS_MET} --os Linux --weight L --network NO --root-only YES --category security --description "Check iptables for empty ruleset"
    if [ ${SKIPTEST} -eq 0 ]; then
        FIND=$(${IPTABLESBINARY} --list --numeric 2> /dev/null | ${EGREPBINARY} -v "^(Chain|target|$)" | ${WCBINARY} -l | ${TRBINARY} -d ' ')
        if [ ! -z "${FIND}" ]; then
            FIREWALL_ACTIVE=1
            if [ ${FIND} -le 10 ]; then
                # Firewall is active, but clearly needs configuration
                FIREWALL_EMPTY_RULESET=1
                LogText "Result: iptables ruleset seems to be empty (found ${FIND} rules)"
                Display --indent 4 --text "- Checking for empty ruleset" --result "${STATUS_WARNING}" --color RED
                ReportWarning ${TEST_NO} "iptables module(s) loaded, but no rules active"
            else
                LogText "Result: one or more rules are available (${FIND} rules)"
                Display --indent 4 --text "- Checking for empty ruleset" --result "${STATUS_OK}" --color GREEN
            fi
        fi
    fi
#
#################################################################################
#
    # Test        : FIRE-4513
    # Description : Check iptables for unused rules
    if [ ! -z "${IPTABLESBINARY}" -a ${IPTABLES_ACTIVE} -eq 1 ]; then PREQS_MET="YES"; else PREQS_MET="NO"; fi
    Register --test-no FIRE-4513 --preqs-met ${PREQS_MET} --os Linux --weight L --network NO --root-only YES --category security --description "Check iptables for unused rules"
    if [ ${SKIPTEST} -eq 0 ]; then
        FIND=$(${IPTABLESBINARY} --list --numeric --line-numbers --verbose | ${AWKBINARY} '{ if ($2=="0") print $1 }' | ${XARGSBINARY})
        if [ -z "${FIND}" ]; then
            Display --indent 4 --text "- Checking for unused rules" --result "${STATUS_OK}" --color GREEN
            LogText "Result: There are no unused rules present"
        else
            Display --indent 4 --text "- Checking for unused rules" --result "${STATUS_FOUND}" --color YELLOW
            LogText "Result: Found one or more possible unused rules"
            LogText "Description: Unused rules can be a sign that the firewall rules aren't optimized or up-to-date"
            LogText "Note: Sometimes rules aren't triggered but still in use. Keep this in mind before cleaning up rules."
            LogText "Output: iptables rule numbers: ${FIND}"
            ReportSuggestion ${TEST_NO} "Check iptables rules to see which rules are currently not used"
            LogText "Tip: iptables --list --numeric --line-numbers --verbose"
        fi
    fi
#
#################################################################################
#
    # Test        : FIRE-4518
    # Description : Checking status of pf firewall components
    # Notes       : Use /dev/pf as first detection method if pf is available
    if [ -e /dev/pf ]; then PREQS_MET="YES"; SKIPREASON=""; else PREQS_MET="NO"; SKIPREASON="No /dev/pf device"; fi
    Register --test-no FIRE-4518 --preqs-met ${PREQS_MET} --skip-reason "${SKIPREASON}" --weight L --network NO --root-only YES --category security --description "Check pf firewall components"
    if [ ${SKIPTEST} -eq 0 ]; then
        PFFOUND=0; PFLOGDFOUND=0

        # Check status with pfctl
        LogText "Test: checking pf status via pfctl"
        if [ ! -z "${PFCTLBINARY}" ]; then
            FIND=$(${PFCTLBINARY} -sa 2>&1 | ${GREPBINARY} "^Status" | ${HEADBINARY} -1 | ${AWKBINARY} '{ print $2 }')
            if [ "${FIND}" = "Disabled" ]; then
                if IsVerbose; then Display --indent 2 --text "- Checking pf status (pfctl)" --result "${STATUS_DISABLED}" --color RED; fi
                LogText "Result: pf is disabled"
                AddHP 0 3
            elif [ "${FIND}" = "Enabled" ]; then
                Display --indent 2 --text "- Checking pf status (pfctl)" --result "${STATUS_ENABLED}" --color GREEN
                LogText "Result: pf is enabled"
                PFFOUND=1
                AddHP 3 3
            else
                Display --indent 2 --text "- Checking pf status (pfctl)" --result "${STATUS_UNKNOWN}" --color YELLOW
                ReportException ${TEST_NO} "Unknown status of pf firewall"
            fi
        fi

        # If we didn't find the status to be enabled, stop searching
        if [ ${PFFOUND} -eq 0 ]; then
            # Check for pf kernel module (FreeBSD and similar)
            LogText "Test: searching for pf kernel module"
            if [ ! -z "${KLDSTATBINARY}" ]; then
                FIND=$(${KLDSTATBINARY} | ${GREPBINARY} 'pf.ko')
                if [ -z "${FIND}" ]; then
                    LogText "Result: Can not find pf KLD"
                else
                    LogText "Result: pf KLD loaded"
                    PFFOUND=1
                fi
              else
                LogText "Result: no kldstat binary, skipping this part"
            fi

            IsRunning pflogd
            if [ ${RUNNING} -eq 1 ]; then
                LogText "Result: found pflog daemon in process list"
                Display --indent 4 --text "- Checking pflogd status" --result "ACTIVE" --color GREEN
                PFFOUND=1
                PFLOGDFOUND=1
            else
                LogText "Result: pflog daemon not found in process list"
            fi
        fi

        if [ ${PFFOUND} -eq 1 ]; then
            FIREWALL_ACTIVE=1
            FIREWALL_SOFTWARE="pf"
            Report "firewall_software[]=pf"
        else
            LogText "Result: pf not running on this system"
        fi
    fi
#
#################################################################################
#
    # Test        : FIRE-4520
    # Description : Check pf configuration consistency
    if [ ${PFFOUND} -eq 1 ]; then PREQS_MET="YES"; else PREQS_MET="NO"; fi
    Register --test-no FIRE-4520 --preqs-met ${PREQS_MET} --weight L --network NO --category security --description "Check pf configuration consistency"
    if [ ${SKIPTEST} -eq 0 ]; then
        LogText "Test: check /etc/pf.conf"
        # Test for warnings (-n don't load the rules)
        if [ -f /etc/pf.conf ]; then
            LogText "Result: /etc/pf.conf exists"
            # Check results from pfctl
            PFWARNINGS=$(${PFCTLBINARY} -n -f /etc/pf.conf -vvv 2>&1 | ${GREPBINARY} -i 'warning')
            if [ -z "${PFWARNINGS}" ]; then
                Display --indent 4 --text "- Checking pf configuration consistency" --result "${STATUS_OK}" --color GREEN
                LogText "Result: no pf filter warnings found"
            else
                Display --indent 4 --text "- Checking pf configuration consistency" --result "${STATUS_WARNING}" --color RED
                LogText "Result: found one or more warnings in the pf filter rules"
                ReportWarning ${TEST_NO} "Found one or more warnings in pf configuration file" "/etc/pf.conf" "text:Run 'pfctl -n -f /etc/pf.conf -vvv' to see available pf warnings"
            fi
        else
            LogText "Result: /etc/pf.conf does NOT exist"
        fi
    fi
#
#################################################################################
#
    # Test        : FIRE-4522
    # Description : Check ipchains
#
#################################################################################
#
    # Test        : FIRE-4524
    # Description : Check for CSF (ConfigServer Security & Firewall)
    Register --test-no FIRE-4524 --weight L --network NO --category security --description "Check for CSF presence"
    if [ ${SKIPTEST} -eq 0 ]; then
        FILE="/etc/csf/csf.conf"
        LogText "Test: check ${FILE}"
        if [ -f ${FILE} ]; then
            LogText "Result: ${FILE} exists"
            FIREWALL_ACTIVE=1
            FIREWALL_SOFTWARE="csf"
            Report "firewall_software[]=csf"
            Display --indent 2 --text "- Checking CSF status (configuration file)" --result "${STATUS_FOUND}" --color GREEN
        else
            LogText "Result: ${FILE} does NOT exist"
        fi
    fi
#
#################################################################################
#
    # Test        : FIRE-4526
    # Description : Check ipf (Solaris)
    if [ ! "${IPFBINARY}" = "" ]; then PREQS_MET="YES"; else PREQS_MET="NO"; fi
    Register --test-no FIRE-4526 --os Solaris --preqs-met ${PREQS_MET} --weight L --network NO --category security --description "Check ipf status"
    if [ ${SKIPTEST} -eq 0 ]; then
        FIND=$(${IPFBINARY} -n -V | ${GREPBINARY} "^Running" | ${AWKBINARY} '{ print $2 }')
        if [ "${FIND}" = "yes" ]; then
            Display --indent 4 --text "- Checking ipf status" --result "${STATUS_RUNNING}" --color GREEN
            LogText "Result: ipf is enabled and running"
            FIREWALL_ACTIVE=1
            FIREWALL_SOFTWARE="ipf"
            Report "firewall_software[]=ipf"
        else
            Display --indent 4 --text "- Checking ipf status" --result "${STATUS_NOT_RUNNING}" --color YELLOW
            LogText "Result: ipf is not running"
        fi
    fi
#
#################################################################################
#
    # Test        : FIRE-4530
    # Description : Check IPFW (FreeBSD)
    Register --test-no FIRE-4530 --os FreeBSD --weight L --network NO --category security --description "Check IPFW status"
    if [ ${SKIPTEST} -eq 0 ]; then
        if [ ! -z "${SYSCTLBINARY}" ]; then
            # For now, only check for IPv4.
            FIND=$(${SYSCTLBINARY} net.inet.ip.fw.enable 2> /dev/null | ${AWKBINARY} '{ print $2 }')
            if [ "${FIND}" = "1" ]; then
                Display --indent 2 --text "- Checking IPFW status" --result "${STATUS_RUNNING}" --color GREEN
                LogText "Result: IPFW is running for IPv4"
                FIREWALL_ACTIVE=1
                FIREWALL_SOFTWARE="ipfw"
                Report "firewall_software[]=ipfw"
                IPFW_ENABLED=`service -e | ${GREPBINARY} -o ipfw`
                if [ "${IPFW_ENABLED}" = "ipfw" ]; then
                    Display --indent 4 --text "- IPFW enabled in /etc/rc.conf" --result "${STATUS_YES}" --color GREEN
                    LogText "Result: IPFW is enabled at start-up for IPv4"
                else
                    Display --indent 4 --text "- ipfw enabled in /etc/rc.conf" --result "${STATUS_NO}" --color YELLOW
                    LogText "Result: IPFW is disabled at start-up for IPv4"
                fi
            else
                if IsVerbose; then Display --indent 2 --text "- Checking IPFW status" --result "${STATUS_NOT_RUNNING}" --color YELLOW; fi
                LogText "Result: IPFW is not running for IPv4"
            fi
        else
            ReportException "${TEST_NO}:1" "No IPFW test available (sysctl missing)"
        fi
    fi
#
#################################################################################
#
    # Test        : FIRE-4532
    # Description : Check Application Firewall in Mac OS X
    if [ -x /usr/libexec/ApplicationFirewall/socketfilterfw ]; then PREQS_MET="YES"; else PREQS_MET="NO"; fi
    Register --test-no FIRE-4532 --weight L --os "MacOS" --preqs-met ${PREQS_MET} --network NO --category security --description "Check macOS application firewall"
    if [ ${SKIPTEST} -eq 0 ]; then
        FIND=$(/usr/libexec/ApplicationFirewall/socketfilterfw --getglobalstate 2> /dev/null | ${GREPBINARY} "Firewall is enabled")
        if [ ! -z "${FIND}" ]; then
            Display --indent 2 --text "- Checking macOS: Application Firewall" --result "${STATUS_ENABLED}" --color GREEN
            AddHP 3 3
            LogText "Result: application firewall of macOS is enabled"
            FIREWALL_ACTIVE=1
            APPLICATION_FIREWALL_ACTIVE=1
            Report "firewall_software[]=macosx-app-fw"
            Report "app_fw[]=macosx-app-fw"
        else
            if IsVerbose; then Display --indent 2 --text "- Checking macOS: Application Firewall" --result "${STATUS_DISABLED}" --color YELLOW; fi
            AddHP 1 3
            LogText "Result: application firewall of macOS is disabled"
        fi
    fi
#
#################################################################################
#
    # Test        : FIRE-4534
    # Description : Check Little Snitch Daemon on macOS
    Register --test-no FIRE-4534 --weight L --os "MacOS" --network NO --category security --description "Check for presence of Little Snitch on macOS"
    if [ ${SKIPTEST} -eq 0 ]; then
        if IsRunning "Little Snitch Daemon"; then
            Display --indent 2 --text "- Checking Little Snitch Daemon" --result "${STATUS_ENABLED}" --color GREEN
            AddHP 3 3
            LogText "Result: little Snitch found"
            FIREWALL_ACTIVE=1
            APPLICATION_FIREWALL_ACTIVE=1
            Report "app_fw[]=little-snitch"
            Report "firewall_software[]=little-snitch"
        else
            if IsVerbose; then Display --indent 2 --text "- Checking Little Snitch Daemon" --result "${STATUS_DISABLED}" --color YELLOW; fi
            AddHP 1 3
            LogText "Result: could not find Little Snitch"
        fi
    fi
#
#################################################################################
#
    # Test        : FIRE-4536
    # Description : Check nftables kernel module
    if [ ! "${NFTBINARY}" = "" ]; then PREQS_MET="YES"; else PREQS_MET="NO"; fi
    Register --test-no FIRE-4536 --os Linux --preqs-met ${PREQS_MET} --weight L --network NO --category security --description "Check nftables status"
    if [ ${SKIPTEST} -eq 0 ]; then
        FIND=$(${LSMODBINARY} | ${AWKBINARY} '{ print $1 }' | ${GREPBINARY} "^nf*_tables")
        if [ ! -z "${FIND}" ]; then
            LogText "Result: found nftables kernel module"
            FIREWALL_SOFTWARE="nftables"
            FIREWALL_ACTIVE=1
            NFTABLES_ACTIVE=1
            Report "firewall_software[]=nftables"
        else
            LogText "Result: no nftables kernel module found"
        fi
    fi
#
#################################################################################
#
    # Test        : FIRE-4538
    # Description : Check nftables configuration
    if [ ! "${NFTBINARY}" = "" ]; then PREQS_MET="YES"; else PREQS_MET="NO"; fi
    Register --test-no FIRE-4538 --os Linux --preqs-met ${PREQS_MET} --weight L --network NO --category security --description "Check nftables basic configuration"
    if [ ${SKIPTEST} -eq 0 ]; then
        # Retrieve nft version
        NFT_VERSION=$(${NFTBINARY} --version 2> /dev/null | ${AWKBINARY} '{ if ($1=="nftables") { print $2 }}' | ${TRBINARY} -d 'v')
        Report "nft_version=${NFT_VERSION}"
        LogText "Result: found version ${NFT_VERSION} of nft"
    fi
#
#################################################################################
#
    # Test        : FIRE-4540
    # Description : Check nftables configuration
    if [ ! "${NFTBINARY}" = "" ]; then PREQS_MET="YES"; else PREQS_MET="NO"; fi
    Register --test-no FIRE-4540 --os Linux --preqs-met ${PREQS_MET} --weight L --network NO --category security --description "Check for empty nftables configuration"
    if [ ${SKIPTEST} -eq 0 ]; then
        # Check for empty ruleset
        NFT_RULES_LENGTH=$(${NFTBINARY} export json 2> /dev/null | wc -c)
        if [ ${NFT_RULES_LENGTH} -le 16 ]; then
            FIREWALL_EMPTY_RULESET=1
            LogText "Result: this firewall set has 16 rules or less and is considered to be empty"
        else
            LogText "Result: found ${NFT_RULES_LENGTH} rules in nftables configuration"
        fi
    fi
#
#################################################################################
#
    # Ideas:
    # Suggestion to disable iptables if nftables is enabled
    # Check for specific features in nftables releases
#
#################################################################################
#
    # Test        : FIRE-4590
    # Description : Check if at least one firewall if active
    Register --test-no FIRE-4590 --weight L --network NO --category security --description "Check firewall status"
    if [ ${SKIPTEST} -eq 0 ]; then
        if [ ${FIREWALL_ACTIVE} -eq 1 ]; then
            Display --indent 2 --text "- Checking host based firewall" --result "ACTIVE" --color GREEN
            LogText "Result: host based firewall or packet filter is active"
            Report "manual[]=Verify if there is a formal process for testing and applying firewall rules"
            Report "manual[]=Verify all traffic is filtered the right way between the different security zones"
            Report "manual[]=Verify if a list is available with all required services"
            # YYY Solaris ipf (determine default policy)
            Report "manual[]=Make sure an explicit deny all is the default policy for all unmatched traffic"
            AddHP 5 5
        else
            Display --indent 2 --text "- Checking host based firewall" --result "NOT ACTIVE" --color YELLOW
            LogText "Result: no host based firewall/packet filter found or configured"
            ReportSuggestion ${TEST_NO} "Configure a firewall/packet filter to filter incoming and outgoing traffic"
            AddHP 0 5
        fi
    fi
#
#################################################################################
#

# Report firewall installed for now, if we found one active. Next step would be determining binaries first and apply additional checks.
Report "firewall_active=${FIREWALL_ACTIVE}"
Report "firewall_empty_ruleset=${FIREWALL_EMPTY_RULESET}"
Report "firewall_installed=${FIREWALL_ACTIVE}"
Report "firewall_software=${FIREWALL_SOFTWARE}"

WaitForKeyPress

#
#================================================================================
# Lynis - Security Auditing and System Hardening for Linux and UNIX - https://cisofy.com