shorewall_code/Shorewall/Perl/prog.header

#     This program is under GPL [http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt]
#
#     (c) 1999-2009 - Tom Eastep (teastep@shorewall.net)
#
#	Options are:
#
#	    -n				  Don't alter Routing
#	    -v and -q			  Standard Shorewall Verbosity control
#
#	Commands are:
#
#	   start			  Starts the firewall
#          refresh                        Refresh the firewall
#	   restart			  Restarts the firewall
#	   reload			  Reload the firewall
#	   clear			  Removes all firewall rules
#	   stop				  Stops the firewall
#	   status			  Displays firewall status
#	   version			  Displays the version of Shorewall that
#	   				  generated this program
#
################################################################################
# Functions imported from /usr/share/shorewall/prog.header
################################################################################
#
# Message to stderr
#
error_message() # $* = Error Message
{
   echo "   $@" >&2
}

#
# Conditionally produce message
#
progress_message() # $* = Message
{
    local timestamp
    timestamp=

    if [ $VERBOSE -gt 1 ]; then
	[ -n "$TIMESTAMP" ] && timestamp="$(date +%H:%M:%S) "
	echo "${timestamp}$@"
    fi

    if [ $LOG_VERBOSE -gt 1 ]; then
        timestamp="$(date +'%b %_d %T') "
        echo "${timestamp}$@" >> $STARTUP_LOG
    fi
}

progress_message2() # $* = Message
{
    local timestamp
    timestamp=

    if [ $VERBOSE -gt 0 ]; then
	[ -n "$TIMESTAMP" ] && timestamp="$(date +%H:%M:%S) "
	echo "${timestamp}$@"
    fi

    if [ $LOG_VERBOSE -gt 0 ]; then
        timestamp="$(date +'%b %_d %T') "
        echo "${timestamp}$@" >> $STARTUP_LOG
    fi
}

progress_message3() # $* = Message
{
    local timestamp
    timestamp=

    if [ $VERBOSE -ge 0 ]; then
	[ -n "$TIMESTAMP" ] && timestamp="$(date +%H:%M:%S) "
	echo "${timestamp}$@"
    fi

    if [ $LOG_VERBOSE -ge 0 ]; then
        timestamp="$(date +'%b %_d %T') "
        echo "${timestamp}$@" >> $STARTUP_LOG
    fi
}

#
# Split a colon-separated list into a space-separated list
#
split() {
    local ifs
    ifs=$IFS
    IFS=:
    echo $*
    IFS=$ifs
}

#
# Search a list looking for a match -- returns zero if a match found
# 1 otherwise
#
list_search() # $1 = element to search for , $2-$n = list
{
    local e
    e=$1

    while [ $# -gt 1 ]; do
	shift
	[ "x$e" = "x$1" ] && return 0
    done

    return 1
}

#
# Suppress all output for a command
#
qt()
{
    "$@" >/dev/null 2>&1
}

qt1()
{
    local status

    while [ 1 ]; do
	"$@" >/dev/null 2>&1
	status=$?
	[ $status -ne 4 ] && return $status
    done
}

#
# Determine if Shorewall is "running"
#
shorewall_is_started() {
    qt1 $IPTABLES -L shorewall -n
}

#
# Echos the fully-qualified name of the calling shell program
#
my_pathname() {
    cd $(dirname $0)
    echo $PWD/$(basename $0)
}

#
# Source a user exit file if it exists
#
run_user_exit() # $1 = file name
{
    local user_exit
    user_exit=$(find_file $1)

    if [ -f $user_exit ]; then
	progress_message "Processing $user_exit ..."
	. $user_exit
    fi
}

#
# Set a standard chain's policy
#
setpolicy() # $1 = name of chain, $2 = policy
{
    run_iptables -P $1 $2
}

#
# Set a standard chain to enable established and related connections
#
setcontinue() # $1 = name of chain
{
    run_iptables -A $1 -m state --state ESTABLISHED,RELATED -j ACCEPT
}

#
# Flush one of the NAT table chains
#
flushnat() # $1 = name of chain
{
    run_iptables -t nat -F $1
}

#
# Flush one of the Mangle table chains
#
flushmangle() # $1 = name of chain
{
    run_iptables -t mangle -F $1
}

#
# Flush and delete all user-defined chains in the filter table
#
deleteallchains() {
    run_iptables -F
    run_iptables -X
}

#
# Load a Kernel Module -- assumes that the variable 'moduledirectories' contains
#                         a space-separated list of directories to search for
#                         the module and that 'moduleloader' contains the
#                         module loader command.
#
loadmodule() # $1 = module name, $2 - * arguments
{
    local modulename
    modulename=$1
    local modulefile
    local suffix

    if ! list_search $modulename $DONT_LOAD $MODULES; then
	shift

	for suffix in $MODULE_SUFFIX ; do
	    for directory in $moduledirectories; do
		modulefile=$directory/${modulename}.${suffix}

		if [ -f $modulefile ]; then
		    case $moduleloader in
			insmod)
			    insmod $modulefile $*
			    ;;
			*)
			    modprobe $modulename $*
			    ;;
		    esac
		    break 2
		fi
	    done
	done
    fi
}

#
# Reload the Modules
#
reload_kernel_modules() {

    local save_modules_dir
    save_modules_dir=$MODULESDIR
    local directory
    local moduledirectories
    moduledirectories=
    local moduleloader
    moduleloader=modprobe
    local uname

    if ! qt mywhich modprobe; then
	moduleloader=insmod
    fi

    [ -n "${MODULE_SUFFIX:=o gz ko o.gz ko.gz}" ]

    [ -z "$MODULESDIR" ] && \
	uname=$(uname -r) && \
	MODULESDIR=/lib/modules/$uname/kernel/net/ipv4/netfilter:/lib/modules/$uname/kernel/net/netfilter:/lib/modules/$uname/extra:/lib/modules/$uname/extra/ipset

    MODULES=$(lsmod | cut -d ' ' -f1)

    for directory in $(split $MODULESDIR); do
	[ -d $directory ] && moduledirectories="$moduledirectories $directory"
    done

    [ -n "$moduledirectories" ] && while read command; do
	eval $command
    done

    MODULESDIR=$save_modules_dir
}

#
# Load kernel modules required for Shorewall
#
load_kernel_modules() # $1 = Yes, if we are to save moduleinfo in $VARDIR
{
    local save_modules_dir
    save_modules_dir=$MODULESDIR
    local directory
    local moduledirectories
    moduledirectories=
    local moduleloader
    moduleloader=modprobe
    local savemoduleinfo
    savemoduleinfo=${1:-Yes} # So old compiled scripts still work
    local uname

    if ! qt mywhich modprobe; then
	moduleloader=insmod
    fi

    [ -n "${MODULE_SUFFIX:=o gz ko o.gz ko.gz}" ]

    [ -z "$MODULESDIR" ] && \
	uname=$(uname -r) && \
	MODULESDIR=/lib/modules/$uname/kernel/net/ipv4/netfilter:/lib/modules/$uname/kernel/net/netfilter:/lib/modules/$uname/extra:/lib/modules/$uname/extra/ipset

    for directory in $(split $MODULESDIR); do
	[ -d $directory ] && moduledirectories="$moduledirectories $directory"
    done

    modules=$(find_file modules)

    if [ -f $modules -a -n "$moduledirectories" ]; then
	MODULES=$(lsmod | cut -d ' ' -f1)
	progress_message "Loading Modules..."
	. $modules
	if [ $savemoduleinfo = Yes ]; then
	    [ -d ${VARDIR} ] || mkdir -p ${VARDIR}
	    echo MODULESDIR="$MODULESDIR" > ${VARDIR}/.modulesdir
	    cp -f $modules ${VARDIR}/.modules
	fi
    elif [ $savemoduleinfo = Yes ]; then
	[ -d ${VARDIR} ] || mkdir -p ${VARDIR}
	> ${VARDIR}/.modulesdir
	> ${VARDIR}/.modules
    fi

    MODULESDIR=$save_modules_dir
}

#
#  Note: The following set of IP address manipulation functions have anomalous
#        behavior when the shell only supports 32-bit signed arithmetic and
#        the IP address is 128.0.0.0 or 128.0.0.1.
#

LEFTSHIFT='<<'

#
# Convert an IP address in dot quad format to an integer
#
decodeaddr() {
    local x
    local temp
    temp=0
    local ifs
    ifs=$IFS

    IFS=.

    for x in $1; do
	temp=$(( $(( $temp $LEFTSHIFT 8 )) | $x ))
    done

    echo $temp

    IFS=$ifs
}

#
# convert an integer to dot quad format
#
encodeaddr() {
    addr=$1
    local x
    local y
    y=$(($addr & 255))

    for x in 1 2 3 ; do
	addr=$(($addr >> 8))
	y=$(($addr & 255)).$y
    done

    echo $y
}

#
# Netmask from CIDR
#
ip_netmask() {
    local vlsm
    vlsm=${1#*/}

    [ $vlsm -eq 0 ] && echo 0 || echo $(( -1 $LEFTSHIFT $(( 32 - $vlsm )) ))
}

#
# Network address from CIDR
#
ip_network() {
    local decodedaddr
    decodedaddr=$(decodeaddr ${1%/*})
    local netmask
    netmask=$(ip_netmask $1)

    echo $(encodeaddr $(($decodedaddr & $netmask)))
}

#
# The following hack is supplied to compensate for the fact that many of
# the popular light-weight Bourne shell derivatives don't support XOR ("^").
#
ip_broadcast() {
    local x
    x=$(( 32 - ${1#*/} ))

    [ $x -eq 32 ] && echo -1 || echo $(( $(( 1 $LEFTSHIFT $x )) - 1 ))
}

#
# Calculate broadcast address from CIDR
#
broadcastaddress() {
    local decodedaddr
    decodedaddr=$(decodeaddr ${1%/*})
    local netmask
    netmask=$(ip_netmask $1)
    local broadcast
    broadcast=$(ip_broadcast $1)

    echo $(encodeaddr $(( $(($decodedaddr & $netmask)) | $broadcast )))
}

#
# Test for network membership
#
in_network() # $1 = IP address, $2 = CIDR network
{
    local netmask
    netmask=$(ip_netmask $2)
    #
    # Use string comparison to work around a broken BusyBox ash in OpenWRT
    #
    test $(( $(decodeaddr $1) & $netmask)) = $(( $(decodeaddr ${2%/*}) & $netmask ))
}

#
# Query NetFilter about the existence of a filter chain
#
chain_exists() # $1 = chain name
{
    qt1 $IPTABLES -L $1 -n
}

#
# Find the value 'dev' in the passed arguments then echo the next value
#

find_device() {
    while [ $# -gt 1 ]; do
	[ "x$1" = xdev ] && echo $2 && return
	shift
    done
}

#
# Find the value 'via' in the passed arguments then echo the next value
#

find_gateway() {
    while [ $# -gt 1 ]; do
	[ "x$1" = xvia ] && echo $2 && return
	shift
    done
}

#
# Find the value 'mtu' in the passed arguments then echo the next value
#

find_mtu() {
    while [ $# -gt 1 ]; do
	[ "x$1" = xmtu ] && echo $2 && return
	shift
    done
}

#
# Find the value 'peer' in the passed arguments then echo the next value up to
# "/"
#

find_peer() {
    while [ $# -gt 1 ]; do
	[ "x$1" = xpeer ] && echo ${2%/*} && return
	shift
    done
}

#
# Find the interfaces that have a route to the passed address - the default
# route is not used.
#

find_rt_interface() {
    $IP -4 route list | while read addr rest; do
	case $addr in
	    */*)
		in_network ${1%/*} $addr && echo $(find_device $rest)
		;;
	    default)
		;;
	    *)
		if [ "$addr" = "$1" -o "$addr/32" = "$1" ]; then
		    echo $(find_device $rest)
		fi
		;;
	esac
    done
}

#
# Try to find the gateway through an interface looking for 'nexthop'

find_nexthop() # $1 = interface
{
    echo $(find_gateway `$IP -4 route list | grep "[[:space:]]nexthop.* $1"`)
}

#
# Find the default route's interface
#
find_default_interface() {
    $IP -4 route list | while read first rest; do
	[ "$first" = default ] && echo $(find_device $rest) && return
    done
}

#
# Echo the name of the interface(s) that will be used to send to the
# passed address
#

find_interface_by_address() {
    local dev
    dev="$(find_rt_interface $1)"
    local first
    local rest

    [ -z "$dev" ] && dev=$(find_default_interface)

    [ -n "$dev" ] && echo $dev
}

#
# Find the interface with the passed MAC address
#

find_interface_by_mac() {
    local mac
    mac=$1
    local first
    local second
    local rest
    local dev

    $IP link list | while read first second rest; do
	case $first in
	    *:)
                dev=$second
		;;
	    *)
	        if [ "$second" = $mac ]; then
		    echo ${dev%:}
		    return
		fi
	esac
    done
}

#
# Determine if Interface is up
#
interface_is_up() {
    [ -n "$($IP link list dev $1 2> /dev/null | grep -e '[<,]UP[,>]')" ]
}

#
# Find interface address--returns the first IP address assigned to the passed
# device
#
find_first_interface_address() # $1 = interface
{
    #
    # get the line of output containing the first IP address
    #
    addr=$($IP -f inet addr show $1 2> /dev/null | grep 'inet .* global' | head -n1)
    #
    # If there wasn't one, bail out now
    #
    [ -n "$addr" ] || startup_error "Can't determine the IP address of $1"
    #
    # Strip off the trailing VLSM mask (or the peer IP in case of a P-t-P link)
    # along with everything else on the line
    #
    echo $addr | sed 's/\s*inet //;s/\/.*//;s/ peer.*//'
}

find_first_interface_address_if_any() # $1 = interface
{
    #
    # get the line of output containing the first IP address
    #
    addr=$($IP -f inet addr show $1 2> /dev/null | grep 'inet .* global' | head -n1)
    #
    # Strip off the trailing VLSM mask (or the peer IP in case of a P-t-P link)
    # along with everything else on the line
    #
    [ -n "$addr" ] && echo $addr | sed 's/\s*inet //;s/\/.*//;s/ peer.*//' || echo 0.0.0.0
}

#
# Determine if interface is usable from a Netfilter prespective
#
interface_is_usable() # $1 = interface
{
    interface_is_up $1 && [ "$(find_first_interface_address_if_any $1)" != 0.0.0.0 ] && run_isusable_exit $1
}

#
# Find interface addresses--returns the set of addresses assigned to the passed
# device
#
find_interface_addresses() # $1 = interface
{
    $IP -f inet addr show $1 2> /dev/null | grep inet\  | sed 's/\s*inet //;s/\/.*//;s/ peer.*//'
}

#
#  echo the list of networks routed out of a given interface
#
get_routed_networks() # $1 = interface name, $2-n = Fatal error message
{
    local address
    local rest

    $IP -4 route show dev $1 2> /dev/null |
	while read address rest; do
	    case "$address" in
		default)
		    if [ $# -gt 1 ]; then
			shift
			fatal_error "$@"
		    else
			echo "WARNING: default route ignored on interface $1" >&2
		    fi
		    ;;
		multicast|broadcast|prohibit|nat|throw|nexthop)
		    ;;
		*)
		    [ "$address" = "${address%/*}" ] && address="${address}/32"
		    echo $address
		    ;;
	    esac
        done
}

#
# Get the broadcast addresses associated with an interface
#
get_interface_bcasts() # $1 = interface
{
    local addresses
    addresses=

    $IP -f inet addr show dev $1 2> /dev/null | grep 'inet.*brd' | sed 's/inet.*brd //; s/scope.*//;' | sort -u
}

#
# Internal version of 'which'
#
mywhich() {
    local dir

    for dir in $(split $PATH); do
	if [ -x $dir/$1 ]; then
	    echo $dir/$1
	    return 0
	fi
    done

    return 2
}

#
# Find a File -- For relative file name, look in each ${CONFIG_PATH} then ${CONFDIR}
#
find_file()
{
    local saveifs
    saveifs=
    local directory

    case $1 in
	/*)
	    echo $1
	    ;;
	*)
	    for directory in $(split $CONFIG_PATH); do
		if [ -f $directory/$1 ]; then
		    echo $directory/$1
		    return
		fi
	    done

	    echo ${CONFDIR}/$1
	    ;;
    esac
}

#
# Set the Shorewall state
#
set_state () # $1 = state
{
    echo "$1 ($(date))" > ${VARDIR}/state
}

#
# Perform variable substitution on the passed argument and echo the result
#
expand() # $@ = contents of variable which may be the name of another variable
{
    eval echo \"$@\"
}

#
# Function for including one file into another
#
INCLUDE() {
    . $(find_file $(expand $@))
}

#
# Delete IP address
#
del_ip_addr() # $1 = address, $2 = interface
{
    [ $(find_first_interface_address_if_any $2) = $1 ] || qt $IP addr del $1 dev $2
}

# Add IP Aliases
#
add_ip_aliases() # $* = List of addresses
{
    local local
    local addresses
    local external
    local interface
    local inet
    local cidr
    local rest
    local val
    local arping
    arping=$(mywhich arping)

    address_details()
    {
	#
	# Folks feel uneasy if they don't see all of the same
	# decoration on these IP addresses that they see when their
	# distro's net config tool adds them. In an attempt to reduce
	# the anxiety level, we have the following code which sets
	# the VLSM and BRD from an existing address in the same networks
	#
	# Get all of the lines that contain inet addresses with broadcast
	#
	$IP -f inet addr show $interface 2> /dev/null | grep 'inet.*brd' | while read inet cidr rest ; do
	    case $cidr in
		*/*)
		    if in_network $external $cidr; then
			echo "/${cidr#*/} brd $(broadcastaddress $cidr)"
			break
		    fi
		    ;;
	    esac
	done
    }

    do_one()
    {
	val=$(address_details)

	$IP addr add ${external}${val} dev $interface $label
	[ -n "$arping" ] && qt $arping -U -c 2 -I $interface $external
	echo "$external $interface" >> $VARDIR/nat
	[ -n "$label" ] && label="with $label"
	progress_message "   IP Address $external added to interface $interface $label"
    }

    progress_message "Adding IP Addresses..."

    while [ $# -gt 0 ]; do
	external=$1
	interface=$2
	label=

	if [ "$interface" != "${interface%:*}" ]; then
	    label="${interface#*:}"
	    interface="${interface%:*}"
	    label="label $interface:$label"
	fi

	shift 2

	list_search $external $(find_interface_addresses $interface) || do_one
    done
}

#
# Detect the gateway through a PPP or DHCP-configured interface
#
detect_dynamic_gateway() { # $1 = interface
    local interface
    interface=$1
    local GATEWAYS
    GATEWAYS=
    local gateway
    #
    # First assume that this is some sort of point-to-point interface
    #
    gateway=$( find_peer $($IP addr list $interface ) )
    #
    # If that didn't work, then try DHCP
    #
    if [ -z "$gateway" -a -f /var/lib/dhcpcd/dhcpcd-${1}.info ]; then
	eval $(grep ^GATEWAYS=  /var/lib/dhcpcd/dhcpcd-${1}.info 2> /dev/null)
	[ -n "$GATEWAYS" ] && GATEWAYS=${GATEWAYS%,*} && gateway=$GATEWAYS
    fi

    if [ -z "$gateway" -a -f /var/lib/dhcp/dhclient-${1}.lease ]; then
	gateway=$(grep 'option routers' /var/lib/dhcp/dhclient-${1}.lease | tail -n 1 | while read j1 j2 gateway; do echo $gateway; return 0; done)
    fi

    if [ -z "$gateway" -a -f /var/lib/dhcp3/dhclient-${1}.leases ]; then
	gateway=$(grep 'option routers' /var/lib/dhcp3/dhclient-${1}.leases | tail -n 1 | while read j1 j2 gateway; do echo $gateway; return 0; done)
    fi

    [ -n "$gateway" ] && echo $gateway
}

#
# Detect the gateway through an interface
#
detect_gateway() # $1 = interface
{
    local interface
    interface=$1
    local gateway
    #
    # First assume that this is some sort of dynamic interface
    #
    gateway=$( detect_dynamic_gateway $interface )
    #
    # Maybe there's a default route through this gateway already
    #
    [ -n "$gateway" ] || gateway=$(find_gateway $($IP -4 route list dev $interface | grep ^default))
    #
    # Last hope -- is there a load-balancing route through the interface?
    #
    [ -n "$gateway" ] || gateway=$(find_nexthop $interface)
    #
    # Be sure we found one
    #
    [ -n "$gateway" ] && echo $gateway
}

#
# Disable IPV6
#
disable_ipv6() {
    local foo
    foo="$($IP -f inet6 addr list 2> /dev/null)"

    if [ -n "$foo" ]; then
	if qt mywhich ip6tables; then
	    ip6tables -P FORWARD DROP
	    ip6tables -P INPUT DROP
	    ip6tables -P OUTPUT DROP
	    ip6tables -F
	    ip6tables -X
	    ip6tables -A OUTPUT -o lo -j ACCEPT
	    ip6tables -A INPUT -i lo -j ACCEPT
	else
	    error_message "WARNING: DISABLE_IPV6=Yes in shorewall.conf but this system does not appear to have ip6tables"
	fi
    fi
}

# Function to truncate a string -- It uses 'cut -b -<n>'
# rather than ${v:first:last} because light-weight shells like ash and
# dash do not support that form of expansion.
#

truncate() # $1 = length
{
    cut -b -${1}
}

#
# Clear the current traffic shaping configuration
#

delete_tc1()
{
    clear_one_tc() {
        $TC qdisc del dev $1 root 2> /dev/null
        $TC qdisc del dev $1 ingress 2> /dev/null

    }

    run_tcclear_exit

    run_ip link list | \
    while read inx interface details; do
        case $inx in
            [0-9]*)
                clear_one_tc ${interface%:}
                ;;
            *)
                ;;
        esac
    done
}

#
# Detect a device's MTU -- echos the passed device's MTU
#
get_device_mtu() # $1 = device
{
    local output
    output="$($IP link list dev $1 2> /dev/null)" # quotes required for /bin/ash

    if [ -n "$output" ]; then
	echo $(find_mtu $output)
    else
	echo 1500
    fi
}

#
# Version of the above that doesn't generate any output for MTU 1500.
# Generates 'mtu <mtu+>' otherwise, where <mtu+> is the device's MTU + 100
#
get_device_mtu1() # $1 = device
{
    local output
    output="$($IP link list dev $1 2> /dev/null)" # quotes required for /bin/ash
    local mtu

    if [ -n "$output" ]; then
	mtu=$(find_mtu $output)
	if [ -n "$mtu" ]; then
	    [ $mtu = 1500 ] || echo mtu $(($mtu + 100))
	fi
    fi

}

#
# Undo changes to routing
#
undo_routing() {

    if [ -z "$NOROUTES"  ]; then
	#
	# Restore rt_tables database
	#
	if [ -f ${VARDIR}/rt_tables ]; then
	    [ -w /etc/iproute2/rt_table -a -z "$KEEP_RT_TABLES" ] && cp -f ${VARDIR}/rt_tables /etc/iproute2/ && progress_message "/etc/iproute2/rt_tables database restored"
	    rm -f ${VARDIR}/rt_tables
	fi
	#
	# Restore the rest of the routing table
	#
	if [ -f ${VARDIR}/undo_routing ]; then
	    . ${VARDIR}/undo_routing
	    progress_message "Shorewall-generated routing tables and routing rules removed"
	    rm -f ${VARDIR}/undo_routing
	fi
    fi

}

#
# Restore the default route that was in place before the initial 'shorewall start'
#
restore_default_route() {
    if [ -z "$NOROUTES" -a -f ${VARDIR}/default_route ]; then
	local default_route
	default_route=
	local route
	local result
	result=1

	while read route ; do
	    case $route in
		default*)
		    if [ -n "$default_route" ]; then
			case "$default_route" in
			    *metric*)
		                #
		                # Don't restore a route with a metric -- we only replace the one with metric == 0
		                #
				qt $IP -4 route delete default metric 0 && \
				    progress_message "Default Route with metric 0 deleted"
				;;
			    *)
				qt $IP -4 route replace $default_route && \
				    result=0 && \
				    progress_message "Default Route (${default_route# }) restored"
				;;
			esac

			break
		    fi

		    default_route="$default_route $route"
		    ;;
		*)
		    default_route="$default_route $route"
		    ;;
	    esac
	done < ${VARDIR}/default_route

	rm -f ${VARDIR}/default_route
    fi

    return $result
}

#
# Determine how to do "echo -e"
#

find_echo() {
    local result

    result=$(echo "a\tb")
    [ ${#result} -eq 3 ] && { echo echo; return; }

    result=$(echo -e "a\tb")
    [ ${#result} -eq 3 ] && { echo "echo -e"; return; }

    result=$(which echo)
    [ -n "$result" ] && { echo "$result -e"; return; }

    echo echo
}

#
# Determine the MAC address of the passed IP through the passed interface
#
find_mac() # $1 = IP address, $2 = interface
{
    if interface_is_usable $2 ; then
	qt ping -nc 1 -t 2 -I $2 $1

	local result
	result=$($IP neigh list |  awk "/^$1 / {print \$5}")

	case $result in
	    \<*\>)
		;;
	    *)
		[ -n "$result" ] && echo $result
		;;
	esac
    fi
}

#
# Flush the conntrack table if $PURGE is non-empty
#
conditionally_flush_conntrack() {

    if [ -n "$PURGE" ]; then
	if [ -n $(which conntrack) ]; then
            conntrack -F
	else
            error_message "WARNING: The '-p' option requires the conntrack utility which does not appear to be installed on this system"
	fi
    fi
}

################################################################################
# End of functions in /usr/share/shorewall/prog.header
################################################################################