diff --git a/ddos-mitigator.sh b/ddos-mitigator.sh
index 5d5153f..8270584 100755
--- a/ddos-mitigator.sh
+++ b/ddos-mitigator.sh
@@ -3,7 +3,7 @@
 #                                                                              #
 # Try and prevent apache overloads by banning IP addresses that have (too)     #
 # many open connections.                                                       #
-# This script uses netstat to determine the connections to a configurable port #
+# This script uses ss to determine the connections to a configurable port      #
 # on the host machine and provides automated GeoIP information retrieval based #
 # the address or the /24-, /16- or /8-subnet thereof. A GeoIP city- or country #
 # database must be installed separately and is provided to the script via a    #
@@ -26,8 +26,8 @@
 #   - net-analyzer/fail2ban (`fail2ban-client`)                                #
 #   - sys-apps/coreutils (`cut`, `id`, `sort`, `touch`, `tr`, `uniq`)          #
 #   - sys-apps/grep (`grep`)                                                   #
+#   - sys-apps/iproute2 (`ss`)                                                 #
 #   - sys-apps/moreutils (`sponge`)                                            #
-#   - sys-apps/net-tools (`netstat`)                                           #
 #   - sys-apps/util-linux (`getopt`)                                           #
 #                                                                              #
 ################################################################################
@@ -36,7 +36,7 @@
 MY_IP="94.199.214.20"
 
 # After this point, no editing is required.
-start=$(date +%s)
+start="$(date +%s)"
 
 # Dependencies of this script. Simple array with the following structure:
 # (command package [...])
@@ -51,8 +51,8 @@ dependencies=(
 	"tr" "sys-apps/coreutils"
 	"uniq" "sys-apps/coreutils"
 	"grep" "sys-apps/grep"
+	"ss" "sys-apps/iproute2"
 	"sponge" "sys-apps/moreutils"
-	"netstat" "sys-apps/net-tools"
 	"getopt" "sys-apps/util-linux"
 )
 
@@ -83,8 +83,8 @@ function is_installed() {
 }
 
 function print_missing_dependency() {
-	local command="$1"
-	local package="$2"
+	local command="${1}"
+	local package="${2}"
 
 	echo "${red}Command ${bold}${command}${reset}${red} not found.${reset} Please install package ${blue}${package}${reset}." >&2
 }
@@ -97,12 +97,12 @@ function check_dependencies() {
 	# 0: true, all installed; 1: false, at least one command/package missing
 	local all_installed=0
 
-	for (( i=0; i<${arraylength}; i+=2 )) ; do
+	for ((i = 0; i < ${arraylength}; i += 2)); do
 		command="${dependencies[$i]}"
-		package="${dependencies[$i+1]}"
+		package="${dependencies[$i + 1]}"
 		is_installed "${command}" "${package}"
 		res=$?
-		if [[ $res -ne 0 ]] ; then
+		if [[ ${res} -ne 0 ]]; then
 			print_missing_dependency "${command}" "${package}"
 			all_installed=1
 		fi
@@ -165,7 +165,7 @@ ENDOFHELP
 }
 
 function exec_as_root() {
-	if [[ $(id -un) == "root" ]] ; then
+	if [[ $(id -un) == "root" ]]; then
 		"$@"
 	else
 		sudo "$@"
@@ -174,22 +174,22 @@ function exec_as_root() {
 
 function filter() {
 	# list of current connections
-	file="$1"
+	file="${1}"
 	# subnet extension, e.g. ".0.0"
-	ext="$2"
+	ext="${2}"
 	# subnet suffix, e.g. "/16"
-	suffix="$3"
+	suffix="${3}"
 	rm -f "${filtered}"
 	touch "${filtered}"
 
 	# Reject already banned addresses
-	while read -r -u3 address ; do
-		if [[ "${banned}" != *"${address}${ext}${suffix}"* ]] ; then
-			echo "${address}" >> "${filtered}"
+	while read -r -u3 address; do
+		if [[ "${banned}" != *"${address}${ext}${suffix}"* ]]; then
+			echo "${address}" >>"${filtered}"
 		else
 			echo "IGNORING ${address}${ext}${suffix}, already banned."
 		fi
-	done 3< "${file}"
+	done 3<"${file}"
 
 	mv "${filtered}" "${file}"
 }
@@ -197,7 +197,7 @@ function filter() {
 function parse_command_line_args() {
 	TEMP=$(getopt -o 'a::,c:,d:,e,j:,n:,p:,h' -l 'auto::,country:,database:,dependencies,jail:,netmask:,port:,help' -- "$@")
 
-	if [ $? -ne 0 ] ; then
+	if [ $? -ne 0 ]; then
 		echo 'Error parsing command line options. Terminating. Invoke with --help for help.' >&2
 		exit 1
 	fi
@@ -205,91 +205,91 @@ function parse_command_line_args() {
 	eval set -- "${TEMP}"
 	unset TEMP
 
-	while true ; do
-		case "$1" in
-			'-a'|'--auto')
-				case "$2" in
-					'')
-						autopilot=1
-					;;
-					*[!0-9]*)
-						echo "Invalid argument for parameter 'auto': '$2'. Invoke with --help for help." >&2
-						exit 1
-					;;
-					*)
-						autopilot="$2"
-					;;
-				esac
-				shift
-			;;
-			'-c'|'--country')
-				IFS=',' read -ra bancountries <<< "$2"
-				if [[ -z ${bancountries[@]// } ]] ; then
-					echo "Invalid argument for parameter 'country': '$2'. Invoke with --help for help." >&2
-					exit 1
-				fi
-				shift
-			;;
-			'-d'|'--database')
-				database="$2"
-				shift
-			;;
-			'-e'|'--dependencies')
-				check_dependencies
-				exit $?
-			;;
-			'-j'|'--jail')
-				jail="$2"
-				shift
-			;;
-			'-n'|'--netmask')
-				case "$2" in
-					'1'|'8')
-						netmask=8
-					;;
-					'2'|'16')
-						netmask=16
-					;;
-					'3'|'24')
-						netmask=24
-					;;
-					'4'|'32')
-						netmask=32
-					;;
-					*)
-						echo "Invalid argument for parameter 'netmask': '$2'. Invoke with --help for help." >&2
-						exit 1
-					;;
-				esac
-				shift
-			;;
-			'-p'|'--port')
-				port="$2"
-				shift
-			;;
-			'-h'|'--help')
-				print_help
-				exit
-			;;
-			'--')
-				shift
-				break
-			;;
-			*)
-				echo "Unknown error on command line argument '$1'. Terminating." >&2
+	while true; do
+		case "${1}" in
+		'-a' | '--auto')
+			case "${2}" in
+			'')
+				autopilot=1
+				;;
+			*[!0-9]*)
+				echo "Invalid argument for parameter 'auto': '${2}'. Invoke with --help for help." >&2
 				exit 1
+				;;
+			*)
+				autopilot="$2"
+				;;
+			esac
+			shift
+			;;
+		'-c' | '--country')
+			IFS=',' read -ra bancountries <<<"${2}"
+			if [[ -z ${bancountries[@]// /} ]]; then
+				echo "Invalid argument for parameter 'country': '${2}'. Invoke with --help for help." >&2
+				exit 1
+			fi
+			shift
+			;;
+		'-d' | '--database')
+			database="${2}"
+			shift
+			;;
+		'-e' | '--dependencies')
+			check_dependencies
+			exit $?
+			;;
+		'-j' | '--jail')
+			jail="${2}"
+			shift
+			;;
+		'-n' | '--netmask')
+			case "${2}" in
+			'1' | '8')
+				netmask=8
+				;;
+			'2' | '16')
+				netmask=16
+				;;
+			'3' | '24')
+				netmask=24
+				;;
+			'4' | '32')
+				netmask=32
+				;;
+			*)
+				echo "Invalid argument for parameter 'netmask': '${2}'. Invoke with --help for help." >&2
+				exit 1
+				;;
+			esac
+			shift
+			;;
+		'-p' | '--port')
+			port="${2}"
+			shift
+			;;
+		'-h' | '--help')
+			print_help
+			exit
+			;;
+		'--')
+			shift
+			break
+			;;
+		*)
+			echo "Unknown error on command line argument '${1}'. Terminating." >&2
+			exit 1
 			;;
 		esac
 		shift
 	done
 
-	if [[ -z "${database}" ]] ; then
-	  echo "No GeoIP database specified. Invoke with --help for more information." >&2
+	if [[ -z "${database}" ]]; then
+		echo "No GeoIP database specified. Invoke with --help for more information." >&2
 		exit 1
 	fi
 
-	if [[ ! -r "${database}" ]] ; then
-	  echo "Database '${database}' is not accessible." >&2
+	if [[ ! -r "${database}" ]]; then
+		echo "Database '${database}' is not accessible." >&2
 		exit 1
 	fi
 }
@@ -301,52 +301,52 @@ function parse_command_line_args() {
 # color to the next happen at different values.
 ################################################################################
 function set_highlight_color() {
-	local count=$1
+	local count=${1}
 	case "${choice}" in
-		"1" )
+	"1")
 		# /32: 0 <= green < 3 <= yellow < 5 <= red
-			if [ $count -ge 5 ] ; then
-				hilite="${red}"
-			elif [ $count -ge 3 ] ; then
-				hilite="${yellow}"
-			else
-				hilite="${green}"
-			fi
+		if [ ${count} -ge 5 ]; then
+			hilite="${red}"
+		elif [ ${count} -ge 3 ]; then
+			hilite="${yellow}"
+		else
+			hilite="${green}"
+		fi
 		;;
-		"2" )
+	"2")
 		# /24: 0 <= green < 7 <= yellow < 13 <= red
-			if [ $count -ge 13 ] ; then
-				hilite="${red}"
-			elif [ $count -ge 7 ] ; then
-				hilite="${yellow}"
-			else
-				hilite="${green}"
-			fi
+		if [ ${count} -ge 13 ]; then
+			hilite="${red}"
+		elif [ ${count} -ge 7 ]; then
+			hilite="${yellow}"
+		else
+			hilite="${green}"
+		fi
 		;;
-		"3" )
+	"3")
 		# /16: 0 <= green < 13 <= yellow < 25 <= red
-			if [ $count -ge 25 ] ; then
-				hilite="${red}"
-			elif [ $count -ge 13 ] ; then
-				hilite="${yellow}"
-			else
-				hilite="${green}"
-			fi
+		if [ ${count} -ge 25 ]; then
+			hilite="${red}"
+		elif [ ${count} -ge 13 ]; then
+			hilite="${yellow}"
+		else
+			hilite="${green}"
+		fi
 		;;
-		"4" )
+	"4")
 		# /8: 0 <= green < 21 <= yellow < 49 <= red
-			if [ $count -ge 49 ] ; then
-				hilite="${red}"
-			elif [ $count -ge 21 ] ; then
-				hilite="${yellow}"
-			else
-				hilite="${green}"
-			fi
+		if [ ${count} -ge 49 ]; then
+			hilite="${red}"
+		elif [ ${count} -ge 21 ]; then
+			hilite="${yellow}"
+		else
+			hilite="${green}"
+		fi
 		;;
-		* )
+	*)
 		# ???: We should never get here. As a fall-back, just use no
 		# highlighting.
-			hilite=""
+		hilite=""
 		;;
 	esac
 }
@@ -357,7 +357,7 @@ function set_highlight_color() {
 # GeoIP database. The user can then choose to ban or ignore the address.
 # Addresses chosen to be banned are appended to the $banlist.
 ################################################################################
-function process_file () {
+function process_file() {
 	local file="${1}"
 	local line=''
 	local count=0
@@ -369,25 +369,25 @@ function process_file () {
 	# Read the contents from filedescriptor 3 (important: Don's use the
 	# standard filedescriptor because we need to handle user input from
 	# within the loop).
-	while IFS= read -r -u3 line ; do
+	while IFS= read -r -u3 line; do
 		line="$(echo "${line}" | tr -s '[:blank:]')"
 		count="$(echo "${line}" | cut -d' ' -f2)"
 		addronly="$(echo "${line}" | cut -d' ' -f3-)${ext}"
 		addrwithsuffix="${addronly}${suffix}"
 		set_highlight_color "${count}"
 		country="$("${curdir}/geoip-lookup.py" -f "${database}" "${addronly}")"
-		if [[ autopilot -eq 0 ]] ; then
+		if [[ ${autopilot} -eq 0 ]]; then
 			echo "Country: '${yellow}${country}${reset}'"
 		fi
 		echo -n "Address ${bold}$((nline++)) of ${nlines}${reset}: \
 Found '${blue}${addrwithsuffix}${reset}' ${hilite}${count}${reset} times."
 
-		if [[ ${autopilot} -eq 0 ]] ; then
+		if [[ ${autopilot} -eq 0 ]]; then
 			echo -n " Ban [y/N/s=No, and skip remaining]? "
 			read banaction
 		else
-			if [[ " ${bancountries[@]} " =~ " ${country} " ]] ; then
-				if [[ $count -ge $autopilot ]] ; then
+			if [[ " ${bancountries[@]} " =~ " ${country} " ]]; then
+				if [[ ${count} -ge ${autopilot} ]]; then
 					echo -en "\n${red}Autopilot active. ${reset}"
 					banaction=y
 				else
@@ -395,7 +395,7 @@ Found '${blue}${addrwithsuffix}${reset}' ${hilite}${count}${reset} times."
 					return
 				fi
 			else
-				if [[ $count -ge $autopilot ]] ; then
+				if [[ ${count} -ge ${autopilot} ]]; then
 					echo -en "\n${green}Autopilot active. ${reset}"
 					banaction=n
 				else
@@ -406,28 +406,28 @@ Found '${blue}${addrwithsuffix}${reset}' ${hilite}${count}${reset} times."
 		fi
 
 		case "${banaction}" in
-			"s" | "S" )
-				echo "Not banning '${blue}${addrwithsuffix}${reset}', \
+		"s" | "S")
+			echo "Not banning '${blue}${addrwithsuffix}${reset}', \
 skipping remaining addresses."
-				return
+			return
 			;;
-			"y" | "Y" )
-				echo "Adding '${blue}${addrwithsuffix}${reset}' to \
+		"y" | "Y")
+			echo "Adding '${blue}${addrwithsuffix}${reset}' to \
 banlist (country=${yellow}${country}${reset})."
-				echo "${addrwithsuffix}" >> "${banlist}"
+			echo "${addrwithsuffix}" >>"${banlist}"
 			;;
-			"n" | "N" | * )
-				echo "Not banning '${blue}${addrwithsuffix}${reset}' (country=${yellow}${country}${reset})."
+		"n" | "N" | *)
+			echo "Not banning '${blue}${addrwithsuffix}${reset}' (country=${yellow}${country}${reset})."
 			;;
 		esac
-	# Here goes: Pipe the file contents via filedescriptor 3.
-	done 3< "${file}"
+		# Here goes: Pipe the file contents via filedescriptor 3.
+	done 3<"${file}"
 	echo "Processed all entries in ${file}."
 }
 
 # Create a temp directory, chdir into it and create the (initially empty)
 # banlist file.
-tmpdir=$(mktemp -d)
+tmpdir="$(mktemp -d)"
 
 # Set up all file paths
 curdir="$(dirname "$0")"
@@ -440,8 +440,6 @@ file24="${tmpdir}/sorted-http-24.txt"
 file32="${tmpdir}/sorted-http-32.txt"
 # This file will contain the addresses to be banned.
 banlist="${tmpdir}/banlist.txt"
-# This file contains the output of the last invocation of whois
-whoisoutput="${tmpdir}/whois.txt"
 
 touch "${banlist}"
 
@@ -457,7 +455,7 @@ parse_command_line_args "$@"
 
 check_dependencies
 dependencies_ok=$?
-if [[ ${dependencies_ok} -ne 0 ]] ; then
+if [[ ${dependencies_ok} -ne 0 ]]; then
 	exit ${dependencies_ok}
 fi
 
@@ -466,14 +464,18 @@ banned="$(exec_as_root fail2ban-client get "${jail}" banip)"
 
 # Determine the current connections to the desired port; store the raw data in
 # $fileraw.
-netstat -nt | grep "${MY_IP}:${port}" | tr -s '[:blank:]' | cut -d' ' -f5 \
-  | cut -d: -f1 | sort > "${fileraw}"
+connections=$(ss -HOn state established "( sport = :${port} )" | tr -s '[:blank:]' | cut -d' ' -f5)
+
+# IPv6-mapped-IPv4: [::ffff:192.168.0.1]:443
+echo "${connections}" | grep '^\[::ffff:' - | cut -d: -f4 | cut -d] -f1 | grep -v '^$' >"${fileraw}"
+# Pure IPv4: 192.168.0.1:443
+echo "${connections}" | grep -v '^\[' - | cut -d: -f1 | grep -v '^$' >>"${fileraw}"
 
 # Group and sort the data into the subnet-specific files.
-cp "${fileraw}" "${file32}"
-cut -d. -f1-3 "${fileraw}" | sort > "${file24}"
-cut -d. -f1-2 "${fileraw}" | sort > "${file16}"
-cut -d. -f1 "${fileraw}" | sort > "${file8}"
+sort "${fileraw}" >"${file32}"
+cut -d. -f1-3 "${fileraw}" | sort >"${file24}"
+cut -d. -f1-2 "${fileraw}" | sort >"${file16}"
+cut -d. -f1 "${fileraw}" | sort >"${file8}"
 
 # Filter already banned addresses
 filter "${file32}" "${ext32}" "${suffix32}"
@@ -493,7 +495,7 @@ nlines24=$(cat "${file24}" | wc -l)
 nlines16=$(cat "${file16}" | wc -l)
 nlines8=$(cat "${file8}" | wc -l)
 
-if [ ${netmask} -eq 0 ] ; then
+if [ ${netmask} -eq 0 ]; then
 	# Now let the user choose which file to process.
 	echo "We've got:"
 	echo "[1] 8bit: ${nlines8} entries"
@@ -506,25 +508,25 @@ if [ ${netmask} -eq 0 ] ; then
 	# $nlines, which will be used after this point. Also, $choice will be
 	# used to color the output based on subnet-type.
 	case "${choice}" in
-		"1" )
-			netmask=8
+	"1")
+		netmask=8
 		;;
-		"2" )
-			netmask=16
+	"2")
+		netmask=16
 		;;
-		"3" )
-			netmask=24
+	"3")
+		netmask=24
 		;;
-		"4" )
-			netmask=32
+	"4")
+		netmask=32
 		;;
-		"Q" | "q" )
-			echo "You chose to abort. That's fine! Have a nice day!"
-			exit
+	"Q" | "q")
+		echo "You chose to abort. That's fine! Have a nice day!"
+		exit
 		;;
-		* )
-			echo "Invalid input: ${choice}. I'm out of here."
-			exit 1
+	*)
+		echo "Invalid input: ${choice}. I'm out of here."
+		exit 1
 		;;
 	esac
 fi
@@ -554,11 +556,11 @@ sudo -k
 
 # Iterate over all addresses in $banlist and invoke fail2ban-client on each
 # one of them.
-while read -r addrwithsuffix ; do
+while read -r addrwithsuffix; do
 	echo "Banning ${addrwithsuffix} ..."
 	exec_as_root fail2ban-client set "${jail}" banip "${addrwithsuffix}"
-done < "${banlist}"
+done <"${banlist}"
 
-end=$(date +%s)
+end="$(date +%s)"
 
 echo "${green}All done in $((end - start)) seconds!${reset}"