freedombone/src/freedombone-utils-firewall

#!/bin/bash
#  _____               _           _
# |   __|___ ___ ___ _| |___ _____| |_ ___ ___ ___
# |   __|  _| -_| -_| . | . |     | . | . |   | -_|
# |__|  |_| |___|___|___|___|_|_|_|___|___|_|_|___|
#
#                              Freedom in the Cloud
#
# Firewall functions
#
# TODO: in future investigate using nftables
#
# License
# =======
#
# Copyright (C) 2014-2018 Bob Mottram <bob@freedombone.net>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

FIREWALL_CONFIG=$HOME/${PROJECT_NAME}-firewall.cfg
FIREWALL_DOMAINS=$HOME/${PROJECT_NAME}-firewall-domains.cfg
FIREWALL_EIFACE=eth0
EXTERNAL_IPV4_ADDRESS=
FIREFOX_TELEMETRY_IP='52.88.27.118'

function save_firewall_settings {
    iptables-save > /etc/firewall.conf
    ip6tables-save > /etc/firewall6.conf
    if [ ! -d /etc/network/if-up.d ]; then
        mkdir /etc/network/if-up.d
    fi
    printf '#!/bin/sh\n' > /etc/network/if-up.d/iptables
    printf 'iptables-restore < /etc/firewall.conf\n' >> /etc/network/if-up.d/iptables
    printf 'ip6tables-restore < /etc/firewall6.conf\n' >> /etc/network/if-up.d/iptables
    if [ -f /etc/network/if-up.d/iptables ]; then
        chmod +x /etc/network/if-up.d/iptables
    fi
}

function block_firefox_telemetry {
    # This shouldn't be needed on a server, but we'll do it anyway
    # to be on the safe side
    # Within firefox source code see submit_telemetry_data.py

    if ! grep -q 'telemetry.mozilla' /etc/hosts; then
	echo '127.0.0.1  telemetry.mozilla.org' >> /etc/hosts
	echo '127.0.0.1  incoming.telemetry.mozilla.org' >> /etc/hosts
    fi
        
    if grep -q "$FIREFOX_TELEMETRY_IP" /etc/firewall.conf; then
        return
    fi

    iptables -A INPUT -s $FIREFOX_TELEMETRY_IP -j DROP
    iptables -A OUTPUT -s $FIREFOX_TELEMETRY_IP -j DROP
    save_firewall_settings
}

function firewall_block_bad_ip_ranges {
    if [ "$INSTALLING_MESH" ]; then
        return
    fi
    if [[ $(is_completed "${FUNCNAME[0]}") == "1" ]]; then
        return
    fi

    # There are various blocklists out there, but they're difficult
    # to verify. Indiscriminately blocking ranges without evidence
    # would be a bad idea.

    # From Wikipedia and elsewhere: US military addresses
    iptables -A INPUT -s 6.0.0.0/8 -j DROP
    iptables -A OUTPUT -s 6.0.0.0/8 -j DROP
    iptables -A INPUT -s 7.0.0.0/8 -j DROP
    iptables -A OUTPUT -s 7.0.0.0/8 -j DROP
    iptables -A INPUT -s 11.0.0.0/8 -j DROP
    iptables -A OUTPUT -s 11.0.0.0/8 -j DROP
    iptables -A INPUT -s 21.0.0.0/8 -j DROP
    iptables -A OUTPUT -s 21.0.0.0/8 -j DROP
    iptables -A INPUT -s 22.0.0.0/8 -j DROP
    iptables -A OUTPUT -s 22.0.0.0/8 -j DROP
    iptables -A INPUT -s 26.0.0.0/8 -j DROP
    iptables -A OUTPUT -s 26.0.0.0/8 -j DROP
    iptables -A INPUT -s 28.0.0.0/8 -j DROP
    iptables -A OUTPUT -s 28.0.0.0/8 -j DROP
    iptables -A INPUT -s 29.0.0.0/8 -j DROP
    iptables -A OUTPUT -s 29.0.0.0/8 -j DROP
    iptables -A INPUT -s 30.0.0.0/8 -j DROP
    iptables -A OUTPUT -s 30.0.0.0/8 -j DROP
    iptables -A INPUT -s 33.0.0.0/8 -j DROP
    iptables -A OUTPUT -s 33.0.0.0/8 -j DROP
    iptables -A INPUT -s 55.0.0.0/8 -j DROP
    iptables -A OUTPUT -s 55.0.0.0/8 -j DROP
    iptables -A INPUT -s 214.0.0.0/8 -j DROP
    iptables -A OUTPUT -s 214.0.0.0/8 -j DROP
    iptables -A INPUT -s 215.0.0.0/8 -j DROP
    iptables -A OUTPUT -s 215.0.0.0/8 -j DROP
    save_firewall_settings
    mark_completed "${FUNCNAME[0]}"
}

function global_rate_limit {
    if ! grep -q "tcp_challenge_ack_limit" /etc/sysctl.conf; then
        echo 'net.ipv4.tcp_challenge_ack_limit = 999999999' >> /etc/sysctl.conf
        sysctl -p -q
    else
        if ! grep -q "net.ipv4.tcp_challenge_ack_limit = 999999999" /etc/sysctl.conf; then
            sed -i 's|net.ipv4.tcp_challenge_ack_limit.*|net.ipv4.tcp_challenge_ack_limit = 999999999|g' /etc/sysctl.conf
            sysctl -p -q
        fi
    fi
}

function enable_ipv6 {
    # endure that ipv6 is enabled and can route
    sed -i 's/net.ipv6.conf.all.disable_ipv6.*/net.ipv6.conf.all.disable_ipv6 = 0/g' /etc/sysctl.conf
    #sed -i "s/net.ipv6.conf.all.accept_redirects.*/net.ipv6.conf.all.accept_redirects = 1/g" /etc/sysctl.conf
    #sed -i "s/net.ipv6.conf.all.accept_source_route.*/net.ipv6.conf.all.accept_source_route = 1/g" /etc/sysctl.conf
    sed -i "s/net.ipv6.conf.all.forwarding.*/net.ipv6.conf.all.forwarding=1/g" /etc/sysctl.conf
    echo 1 > /proc/sys/net/ipv6/conf/all/forwarding
}

function firewall_disable_vpn {
    firewall_remove VPN 1194
    iptables -D INPUT -i ${FIREWALL_EIFACE} -m state --state NEW -p tcp --dport 1194 -j ACCEPT
    iptables -D INPUT -i tun+ -j ACCEPT
    iptables -D FORWARD -i tun+ -j ACCEPT
    iptables -D FORWARD -i tun+ -o ${FIREWALL_EIFACE} -m state --state RELATED,ESTABLISHED -j ACCEPT
    iptables -D FORWARD -i ${FIREWALL_EIFACE} -o tun+ -m state --state RELATED,ESTABLISHED -j ACCEPT
    iptables -t nat -D POSTROUTING -s 10.8.0.0/24 -o ${FIREWALL_EIFACE} -j MASQUERADE
    iptables -D OUTPUT -o tun+ -j ACCEPT
    save_firewall_settings
}

function firewall_enable_vpn {
    firewall_add VPN 1194 tcp
    iptables -A INPUT -i ${FIREWALL_EIFACE} -m state --state NEW -p tcp --dport 1194 -j ACCEPT
    iptables -A INPUT -i tun+ -j ACCEPT
    iptables -A FORWARD -i tun+ -j ACCEPT
    iptables -A FORWARD -i tun+ -o ${FIREWALL_EIFACE} -m state --state RELATED,ESTABLISHED -j ACCEPT
    iptables -A FORWARD -i ${FIREWALL_EIFACE} -o tun+ -m state --state RELATED,ESTABLISHED -j ACCEPT
    iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o ${FIREWALL_EIFACE} -j MASQUERADE
    iptables -A OUTPUT -o tun+ -j ACCEPT
    save_firewall_settings
}

function configure_firewall {
    if [ "$INSTALLING_MESH" ]; then
        mesh_firewall
        return
    fi
    if grep -q "RELATED" /etc/firewall.conf; then
        # recreate the firewall to remove RELATED
        sed -i "/firewall/d" "$COMPLETION_FILE"
    fi
    if [[ $(is_completed "${FUNCNAME[0]}") == "1" ]]; then
        return
    fi
    if [[ $INSTALLED_WITHIN_DOCKER == "yes" ]]; then
        # docker does its own firewalling
        return
    fi
    iptables -P INPUT ACCEPT
    ip6tables -P INPUT ACCEPT
    iptables -F
    ip6tables -F
    iptables -t nat -F
    ip6tables -t nat -F
    iptables -X
    ip6tables -X
    iptables -P INPUT DROP
    ip6tables -P INPUT DROP
    iptables -P FORWARD DROP
    ip6tables -P FORWARD DROP
    iptables -A INPUT -i lo -j ACCEPT
    iptables -A INPUT -m conntrack --ctstate ESTABLISHED -j ACCEPT

    # Drop invalid packets
    iptables -t mangle -A PREROUTING -m conntrack --ctstate INVALID -j DROP

    # Make sure incoming tcp connections are SYN packets
    iptables -A INPUT -p tcp ! --syn -m state --state NEW -j DROP
    iptables -t mangle -A PREROUTING -p tcp ! --syn -m conntrack --ctstate NEW -j DROP

    # Drop SYN packets with suspicious MSS value
    iptables -t mangle -A PREROUTING -p tcp -m conntrack --ctstate NEW -m tcpmss ! --mss 536:65535 -j DROP

    # Drop packets with incoming fragments
    iptables -A INPUT -f -j DROP

    # Drop bogons
    iptables -A INPUT -p tcp --tcp-flags ALL ALL -j DROP
    iptables -A INPUT -p tcp --tcp-flags ALL FIN,PSH,URG -j DROP
    iptables -A INPUT -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP
    iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j DROP
    iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,SYN FIN,SYN -j DROP
    iptables -t mangle -A PREROUTING -p tcp --tcp-flags SYN,RST SYN,RST -j DROP
    iptables -t mangle -A PREROUTING -p tcp --tcp-flags SYN,FIN SYN,FIN -j DROP
    iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,RST FIN,RST -j DROP
    iptables -t mangle -A PREROUTING -p tcp --tcp-flags FIN,ACK FIN -j DROP
    iptables -t mangle -A PREROUTING -p tcp --tcp-flags ACK,URG URG -j DROP
    iptables -t mangle -A PREROUTING -p tcp --tcp-flags ACK,FIN FIN -j DROP
    iptables -t mangle -A PREROUTING -p tcp --tcp-flags ACK,PSH PSH -j DROP
    iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL ALL -j DROP
    iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL NONE -j DROP
    iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL FIN,PSH,URG -j DROP
    iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL SYN,FIN,PSH,URG -j DROP
    iptables -t mangle -A PREROUTING -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP

    # Incoming malformed NULL packets:
    iptables -A INPUT -p tcp --tcp-flags ALL NONE -j DROP

    mark_completed "${FUNCNAME[0]}"
}

function firewall_drop_telnet {
    if [[ $(is_completed "${FUNCNAME[0]}") == "1" ]]; then
        return
    fi
    # telnet isn't enabled as an input and we can also
    # drop any outgoing telnet, just in case
    iptables -A OUTPUT -p tcp --dport telnet -j REJECT
    iptables -A OUTPUT -p udp --dport telnet -j REJECT
    function_check save_firewall_settings
    save_firewall_settings
    mark_completed "${FUNCNAME[0]}"
}

function configure_firewall_ping {
    if [[ $(is_completed "${FUNCNAME[0]}") == "1" ]]; then
        return
    fi
    # Only allow ping for mesh installs
    if [[ $SYSTEM_TYPE != "mesh"* ]]; then
        return
    fi
    iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT
    iptables -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT
    function_check save_firewall_settings
    save_firewall_settings
    mark_completed "${FUNCNAME[0]}"
}

function configure_internet_protocol {
    if [[ $(is_completed "${FUNCNAME[0]}") == "1" ]]; then
        return
    fi
    if [[ $SYSTEM_TYPE == "mesh"* ]]; then
        return
    fi

    sed -i "s/#net.ipv4.tcp_syncookies.*/net.ipv4.tcp_syncookies=1/g" /etc/sysctl.conf
    sed -i "s/#net.ipv4.conf.all.accept_redirects.*/net.ipv4.conf.all.accept_redirects = 0/g" /etc/sysctl.conf
    sed -i "s/#net.ipv6.conf.all.accept_redirects.*/net.ipv6.conf.all.accept_redirects = 0/g" /etc/sysctl.conf
    sed -i "s/#net.ipv4.conf.all.send_redirects.*/net.ipv4.conf.all.send_redirects = 0/g" /etc/sysctl.conf
    sed -i "s/#net.ipv4.conf.all.accept_source_route.*/net.ipv4.conf.all.accept_source_route = 0/g" /etc/sysctl.conf
    sed -i "s/#net.ipv6.conf.all.accept_source_route.*/net.ipv6.conf.all.accept_source_route = 0/g" /etc/sysctl.conf
    sed -i "s/#net.ipv4.conf.default.rp_filter.*/net.ipv4.conf.default.rp_filter=1/g" /etc/sysctl.conf
    sed -i "s/#net.ipv4.conf.all.rp_filter.*/net.ipv4.conf.all.rp_filter=1/g" /etc/sysctl.conf
    sed -i "s/#net.ipv4.ip_forward.*/net.ipv4.ip_forward=0/g" /etc/sysctl.conf
    sed -i "s/#net.ipv6.conf.all.forwarding.*/net.ipv6.conf.all.forwarding=0/g" /etc/sysctl.conf

    sed -i "s/# net.ipv4.tcp_syncookies.*/net.ipv4.tcp_syncookies=1/g" /etc/sysctl.conf
    sed -i "s/# net.ipv4.conf.all.accept_redirects.*/net.ipv4.conf.all.accept_redirects = 0/g" /etc/sysctl.conf
    sed -i "s/# net.ipv6.conf.all.accept_redirects.*/net.ipv6.conf.all.accept_redirects = 0/g" /etc/sysctl.conf
    sed -i "s/# net.ipv4.conf.all.send_redirects.*/net.ipv4.conf.all.send_redirects = 0/g" /etc/sysctl.conf
    sed -i "s/# net.ipv4.conf.all.accept_source_route.*/net.ipv4.conf.all.accept_source_route = 0/g" /etc/sysctl.conf
    sed -i "s/# net.ipv6.conf.all.accept_source_route.*/net.ipv6.conf.all.accept_source_route = 0/g" /etc/sysctl.conf
    sed -i "s/# net.ipv4.conf.default.rp_filter.*/net.ipv4.conf.default.rp_filter=1/g" /etc/sysctl.conf
    sed -i "s/# net.ipv4.conf.all.rp_filter.*/net.ipv4.conf.all.rp_filter=1/g" /etc/sysctl.conf
    sed -i "s/# net.ipv4.ip_forward.*/net.ipv4.ip_forward=0/g" /etc/sysctl.conf
    sed -i "s/# net.ipv6.conf.all.forwarding.*/net.ipv6.conf.all.forwarding=0/g" /etc/sysctl.conf


    if ! grep -q "ignore pings" /etc/sysctl.conf; then
        echo '# ignore pings' >> /etc/sysctl.conf
        echo 'net.ipv4.icmp_echo_ignore_all = 1' >> /etc/sysctl.conf
        #echo 'net.ipv6.icmp_echo_ignore_all = 1' >> /etc/sysctl.conf
    fi
    if ! grep -q "disable ipv6" /etc/sysctl.conf; then
        echo '# disable ipv6' >> /etc/sysctl.conf
        echo 'net.ipv6.conf.all.disable_ipv6 = 1' >> /etc/sysctl.conf
    fi
    if ! grep -q "net.ipv4.tcp_synack_retries" /etc/sysctl.conf; then
        echo 'net.ipv4.tcp_synack_retries = 2' >> /etc/sysctl.conf
        echo 'net.ipv4.tcp_syn_retries = 1' >> /etc/sysctl.conf
    fi
    if ! grep -q "keepalive" /etc/sysctl.conf; then
        { echo '# keepalive';
          echo 'net.ipv4.tcp_keepalive_probes = 9';
          echo 'net.ipv4.tcp_keepalive_intvl = 75';
          echo 'net.ipv4.tcp_keepalive_time = 7200'; } >> /etc/sysctl.conf
    fi
    if ! grep -q "net.ipv4.conf.default.send_redirects" /etc/sysctl.conf; then
        echo "net.ipv4.conf.default.send_redirects = 0" >> /etc/sysctl.conf
    else
        sed -i "s|# net.ipv4.conf.default.send_redirects.*|net.ipv4.conf.default.send_redirects = 0|g" /etc/sysctl.conf
        sed -i "s|#net.ipv4.conf.default.send_redirects.*|net.ipv4.conf.default.send_redirects = 0|g" /etc/sysctl.conf
        sed -i "s|net.ipv4.conf.default.send_redirects.*|net.ipv4.conf.default.send_redirects = 0|g" /etc/sysctl.conf
    fi
    if ! grep -q "net.ipv4.conf.all.secure_redirects" /etc/sysctl.conf; then
        echo "net.ipv4.conf.all.secure_redirects = 0" >> /etc/sysctl.conf
    else
        sed -i "s|# net.ipv4.conf.all.secure_redirects.*|net.ipv4.conf.all.secure_redirects = 0|g" /etc/sysctl.conf
        sed -i "s|#net.ipv4.conf.all.secure_redirects.*|net.ipv4.conf.all.secure_redirects = 0|g" /etc/sysctl.conf
        sed -i "s|net.ipv4.conf.all.secure_redirects.*|net.ipv4.conf.all.secure_redirects = 0|g" /etc/sysctl.conf
    fi
    if ! grep -q "net.ipv4.conf.default.accept_source_route" /etc/sysctl.conf; then
        echo "net.ipv4.conf.default.accept_source_route = 0" >> /etc/sysctl.conf
    else
        sed -i "s|# net.ipv4.conf.default.accept_source_route.*|net.ipv4.conf.default.accept_source_route = 0|g" /etc/sysctl.conf
        sed -i "s|#net.ipv4.conf.default.accept_source_route.*|net.ipv4.conf.default.accept_source_route = 0|g" /etc/sysctl.conf
        sed -i "s|net.ipv4.conf.default.accept_source_route.*|net.ipv4.conf.default.accept_source_route = 0|g" /etc/sysctl.conf
    fi
    if ! grep -q "net.ipv4.conf.default.secure_redirects" /etc/sysctl.conf; then
        echo "net.ipv4.conf.default.secure_redirects = 0" >> /etc/sysctl.conf
    else
        sed -i "s|# net.ipv4.conf.default.secure_redirects.*|net.ipv4.conf.default.secure_redirects = 0|g" /etc/sysctl.conf
        sed -i "s|#net.ipv4.conf.default.secure_redirects.*|net.ipv4.conf.default.secure_redirects = 0|g" /etc/sysctl.conf
        sed -i "s|net.ipv4.conf.default.secure_redirects.*|net.ipv4.conf.default.secure_redirects = 0|g" /etc/sysctl.conf
    fi
    if ! grep -q "net.ipv4.conf.default.accept_redirects" /etc/sysctl.conf; then
        echo "net.ipv4.conf.default.accept_redirects = 0" >> /etc/sysctl.conf
    else
        sed -i "s|# net.ipv4.conf.default.accept_redirects.*|net.ipv4.conf.default.accept_redirects = 0|g" /etc/sysctl.conf
        sed -i "s|#net.ipv4.conf.default.accept_redirects.*|net.ipv4.conf.default.accept_redirects = 0|g" /etc/sysctl.conf
        sed -i "s|net.ipv4.conf.default.accept_redirects.*|net.ipv4.conf.default.accept_redirects = 0|g" /etc/sysctl.conf
    fi

    # Randomize kernel
    if ! grep -q "kernel.randomize_va_space" /etc/sysctl.conf; then
        echo "kernel.randomize_va_space=2" >> /etc/sysctl.conf
    else
        sed -i 's|kernel.randomize_va_space.*|kernel.randomize_va_space=2|g' /etc/sysctl.conf
    fi

    # Turn off the tcp_timestamps
    if ! grep -q "net.ipv4.tcp_timestamps" /etc/sysctl.conf; then
        echo "net.ipv4.tcp_timestamps=0" >> /etc/sysctl.conf
    else
        sed -i 's|net.ipv4.tcp_timestamps.*|net.ipv4.tcp_timestamps=0|g' /etc/sysctl.conf
    fi
    /sbin/sysctl -p
    mark_completed "${FUNCNAME[0]}"
}

function mesh_firewall {
    # shellcheck disable=SC2154
    FIREWALL_FILENAME="${rootdir}/etc/systemd/system/meshfirewall.service"
    MESH_FIREWALL_SCRIPT=${rootdir}/usr/bin/mesh-firewall

    if ! grep -q 'telemetry.mozilla' ${rootdir}/etc/hosts; then
	echo '127.0.0.1       telemetry.mozilla.org' >> ${rootdir}/etc/hosts
	echo '127.0.0.1       incoming.telemetry.mozilla.org' >> ${rootdir}/etc/hosts
    fi

    if ! grep -q 'facebook' ${rootdir}/etc/hosts; then
	{ echo '127.0.0.1       www.facebook.com';
	  echo '127.0.0.1       facebook.com';
	  echo '127.0.0.1       static.ak.fbcdn.net';
	  echo '127.0.0.1       www.static.ak.fbcdn.net';
	  echo '127.0.0.1       login.facebook.com';
	  echo '127.0.0.1       www.login.facebook.com';
	  echo '127.0.0.1       fbcdn.net';
	  echo '127.0.0.1       www.fbcdn.net';
	  echo '127.0.0.1       fbcdn.com';
	  echo '127.0.0.1       www.fbcdn.com';
	  echo '127.0.0.1       static.ak.connect.facebook.com';
	  echo '127.0.0.1       www.static.ak.connect.facebook.com'; } >> ${rootdir}/etc/hosts	
    fi
    
    if ! grep -q 'google' ${rootdir}/etc/hosts; then
	{ echo '127.0.0.1       www.google-analytics.com';
	  echo '127.0.0.1       google-analytics.com';
	  echo '127.0.0.1       ssl.google-analytics.com'; } >> ${rootdir}/etc/hosts
    fi    
    
    { echo '#!/bin/bash';
      echo 'iptables -P INPUT ACCEPT';
      echo 'ip6tables -P INPUT ACCEPT';
      echo 'iptables -F';
      echo 'ip6tables -F';
      echo 'iptables -t nat -F';
      echo 'ip6tables -t nat -F';
      echo 'iptables -X';
      echo 'ip6tables -X';
      echo 'iptables -P INPUT DROP';
      echo 'ip6tables -P INPUT DROP';
      echo 'iptables -A INPUT -i lo -j ACCEPT';
      echo 'ip6tables -A INPUT -i lo -j ACCEPT';
      echo 'iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT';
      echo 'ip6tables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT';
      echo '';
      echo '# Make sure incoming tcp connections are SYN packets';
      echo 'iptables -A INPUT -p tcp ! --syn -m state --state NEW -j DROP';
      echo 'ip6tables -A INPUT -p tcp ! --syn -m state --state NEW -j DROP';
      echo '';
      echo '# Drop packets with incoming fragments';
      echo 'iptables -A INPUT -f -j DROP';
      echo 'ip6tables -A INPUT -f -j DROP';
      echo '';
      echo '# Drop bogons';
      echo 'iptables -A INPUT -p tcp --tcp-flags ALL ALL -j DROP';
      echo 'ip6tables -A INPUT -p tcp --tcp-flags ALL ALL -j DROP';
      echo 'iptables -A INPUT -p tcp --tcp-flags ALL FIN,PSH,URG -j DROP';
      echo 'ip6tables -A INPUT -p tcp --tcp-flags ALL FIN,PSH,URG -j DROP';
      echo 'iptables -A INPUT -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP';
      echo 'ip6tables -A INPUT -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP';
      echo '';
      echo '# Incoming malformed NULL packets:';
      echo 'iptables -A INPUT -p tcp --tcp-flags ALL NONE -j DROP';
      echo 'ip6tables -A INPUT -p tcp --tcp-flags ALL NONE -j DROP';
      echo '';
      echo "iptables -A INPUT -p tcp --dport $TOX_PORT -j ACCEPT";
      echo "ip6tables -A INPUT -p tcp --dport $TOX_PORT -j ACCEPT";
      echo "iptables -A INPUT -p udp --dport $ZERONET_PORT -j ACCEPT";
      echo "ip6tables -A INPUT -p udp --dport $ZERONET_PORT -j ACCEPT";
      echo "iptables -A INPUT -p tcp --dport $ZERONET_PORT -j ACCEPT";
      echo "ip6tables -A INPUT -p tcp --dport $ZERONET_PORT -j ACCEPT";
      echo "iptables -A INPUT -p udp --dport $TRACKER_PORT -j ACCEPT";
      echo "ip6tables -A INPUT -p udp --dport $TRACKER_PORT -j ACCEPT";
      echo "iptables -A INPUT -p tcp --dport $TRACKER_PORT -j ACCEPT";
      echo "ip6tables -A INPUT -p tcp --dport $TRACKER_PORT -j ACCEPT";
      echo "iptables -A INPUT -p udp --dport 1900 -j ACCEPT";
      echo "ip6tables -A INPUT -p udp --dport 1900 -j ACCEPT";
      echo "iptables -A INPUT -s $FIREFOX_TELEMETRY_IP -j DROP";
      echo "iptables -A OUTPUT -s $FIREFOX_TELEMETRY_IP -j DROP"; } > "$MESH_FIREWALL_SCRIPT"
    chmod +x "$MESH_FIREWALL_SCRIPT"

    { echo '[Unit]';
      echo 'Description=Mesh Firewall';
      echo '';
      echo '[Service]';
      echo 'Type=oneshot';
      echo 'ExecStart=/usr/bin/mesh-firewall';
      echo 'RemainAfterExit=no';
      echo '';
      echo 'TimeoutSec=30';
      echo '';
      echo '[Install]';
      echo 'WantedBy=multi-user.target'; } > "$FIREWALL_FILENAME"
    chmod +x "$FIREWALL_FILENAME"
    chroot "$rootdir" systemctl enable meshfirewall
}

function firewall_add {
    firewall_name=$(string="$1" ; echo "${string// /-}")
    firewall_port=$2
    firewall_protocol="$3"

    if ! grep -q "${firewall_name}=${firewall_port}" "$FIREWALL_CONFIG"; then
        echo "${firewall_name}=${firewall_port}" >> "$FIREWALL_CONFIG"
        if [ ! "${firewall_protocol}" ]; then
            if ! iptables -C INPUT -p udp --dport "${firewall_port}" -j ACCEPT; then
                iptables -A INPUT -p udp --dport "${firewall_port}" -j ACCEPT
            fi

            if ! iptables -C INPUT -p tcp --dport "${firewall_port}" -j ACCEPT; then
                iptables -A INPUT -p tcp --dport "${firewall_port}" -j ACCEPT
            fi
        else
            if [[ "${firewall_protocol}" == *"udp"* ]]; then
                if ! iptables -C INPUT -p udp --dport "${firewall_port}" -j ACCEPT; then
                    iptables -A INPUT -p udp --dport "${firewall_port}" -j ACCEPT
                fi
            fi
            if [[ "${firewall_protocol}" == *"tcp"* ]]; then
                if ! iptables -C INPUT -p tcp --dport "${firewall_port}" -j ACCEPT; then
                    iptables -A INPUT -p tcp --dport "${firewall_port}" -j ACCEPT
                fi
            fi
        fi
        save_firewall_settings
    fi
}

function firewall_add_range {
    firewall_name=$(string="$1" ; echo "${string// /-}")
    firewall_port_start=$2
    firewall_port_end=$3
    firewall_protocol="$4"

    if ! grep -q "${firewall_name}=${firewall_port_start}:${firewall_port_end}" "$FIREWALL_CONFIG"; then
        echo "${firewall_name}=${firewall_port_start}:${firewall_port_end}" >> "$FIREWALL_CONFIG"
        if [ ! "${firewall_protocol}" ]; then
            if ! iptables -C INPUT -p udp --dport "${firewall_port_start}":"${firewall_port_end}" -j ACCEPT; then
                iptables -A INPUT -p udp --dport "${firewall_port_start}":"${firewall_port_end}" -j ACCEPT
            fi
            if ! iptables -C INPUT -p tcp --dport "${firewall_port_start}":"${firewall_port_end}" -j ACCEPT; then
                iptables -A INPUT -p tcp --dport "${firewall_port_start}":"${firewall_port_end}" -j ACCEPT
            fi
        else
            if [[ "${firewall_protocol}" == *"udp"* ]]; then
                if ! iptables -C INPUT -p udp --dport "${firewall_port_start}":"${firewall_port_end}" -j ACCEPT; then
                    iptables -A INPUT -p udp --dport "${firewall_port_start}":"${firewall_port_end}" -j ACCEPT
                fi
            fi
            if [[ "${firewall_protocol}" == *"tcp"* ]]; then
                if ! iptables -C INPUT -p tcp --dport "${firewall_port_start}":"${firewall_port_end}" -j ACCEPT; then
                    iptables -A INPUT -p tcp --dport "${firewall_port_start}":"${firewall_port_end}" -j ACCEPT
                fi
            fi
        fi
        save_firewall_settings
    fi
}

function firewall_handle_port_scans {
    if [[ $(is_completed "${FUNCNAME[0]}") == "1" ]]; then
        return
    fi
    # only works for high frequency port scanning

    # flooding of RST packets, smurf attack Rejection
    iptables -A INPUT -p tcp -m tcp --tcp-flags RST RST -m limit --limit 2/second --limit-burst 2 -j ACCEPT

    # Protecting portscans
    # Attacking IP will be locked for 24 hours (3600 x 24 = 86400 Seconds)
    iptables -A INPUT -m recent --name portscan --rcheck --seconds 86400 -j DROP
    iptables -A FORWARD -m recent --name portscan --rcheck --seconds 86400 -j DROP

    # Remove attacking IP after 24 hours
    iptables -A INPUT -m recent --name portscan --remove
    iptables -A FORWARD -m recent --name portscan --remove

    # These rules add scanners to the portscan list, and log the attempt.
    iptables -A INPUT -p tcp -m tcp --dport 139 -m recent --name portscan --set -j LOG --log-prefix "portscan:"
    iptables -A INPUT -p tcp -m tcp --dport 139 -m recent --name portscan --set -j DROP

    iptables -A FORWARD -p tcp -m tcp --dport 139 -m recent --name portscan --set -j LOG --log-prefix "portscan:"
    iptables -A FORWARD -p tcp -m tcp --dport 139 -m recent --name portscan --set -j DROP
    save_firewall_settings
    mark_completed "${FUNCNAME[0]}"
}

function firewall_remove {
    firewall_port=$1
    firewall_protocol="$2"

    if [ ! -f "$FIREWALL_CONFIG" ]; then
        return
    fi

    if grep -q "=${firewall_port}" "$FIREWALL_CONFIG"; then
        if [ ! "${firewall_protocol}" ]; then
            iptables -D INPUT -p udp --dport "${firewall_port}" -j ACCEPT
            iptables -D INPUT -p tcp --dport "${firewall_port}" -j ACCEPT
        else
            if [[ "${firewall_protocol}" == *"udp"* ]]; then
                iptables -D INPUT -p udp --dport "${firewall_port}" -j ACCEPT
            fi
            if [[ "${firewall_protocol}" == *"tcp"* ]]; then
                iptables -D INPUT -p tcp --dport "${firewall_port}" -j ACCEPT
            fi
        fi
        sed -i "/=${firewall_port}/d" "$FIREWALL_CONFIG"
        save_firewall_settings
    fi
}

function domain_to_hex_string {
    domain="$1"
    ctr=1
    segment=$(echo "$domain" | awk -F '.' -v value="$ctr" '{print $value}')
    while [ ${#segment} -gt 0 ]
    do
        characters=$(echo -n "$segment" | wc -c)
        hexnum=$(echo "obase=16; $characters" | bc)
        echo -n "|"
        if [ "$(echo -n "$hexnum" | wc -c)" -lt 2 ]; then
            echo -n "0"
        fi
        echo -n "$hexnum|$segment"
        ctr=$((ctr + 1))
        segment=$(echo "$domain" | awk -F '.' -v value="$ctr" '{print $value}')
    done
    echo ""
}

function firewall_block_domain {
    blocked_domain="$1"
    if [[ "$blocked_domain" == *'@'* ]]; then
        # Don't try to block email/microblog addresses
        echo "${blocked_domain}" >> "$FIREWALL_DOMAINS"
        return
    fi
    if ! grep -q "$blocked_domain" "$FIREWALL_DOMAINS"; then
        hexstr=$(domain_to_hex_string "$blocked_domain")
        if ! iptables -C INPUT -p udp --dport 53 -m string --hex-string "$hexstr" --algo bm -j DROP; then
            iptables -A INPUT -p udp --dport 53 -m string --hex-string "$hexstr" --algo bm -j DROP
            iptables -A INPUT -p tcp --dport 53 -m string --hex-string "$hexstr" --algo bm -j DROP
            iptables -A OUTPUT -p udp --dport 53 -m string --hex-string "$hexstr" --algo bm -j DROP
            iptables -A OUTPUT -p tcp --dport 53 -m string --hex-string "$hexstr" --algo bm -j DROP
            iptables -I FORWARD -p udp --dport 53 -m string --hex-string "$hexstr" --algo bm -j DROP
            iptables -I FORWARD -p tcp --dport 53 -m string --hex-string "$hexstr" --algo bm -j DROP
            echo "${blocked_domain}" >> "$FIREWALL_DOMAINS"
            save_firewall_settings
        fi

        # run the blocking rules now
        if [ -f /usr/bin/gnusocial-firewall ]; then
            /usr/bin/gnusocial-firewall
        fi
        if [ -f /usr/bin/postactiv-firewall ]; then
            /usr/bin/postactiv-firewall
        fi
        if [ -f /usr/bin/pleroma-blocking ]; then
            /usr/bin/pleroma-blocking
        fi
    fi
}

function firewall_block_ip {
    blocked_ip="$1"
    if [[ "$blocked_ip" == *'@'* ]]; then
        # Don't try to block email/microblog addresses
        return
    fi
    if ! grep -q "$blocked_ip" "$FIREWALL_DOMAINS"; then
        if ! iptables -C INPUT -s "$blocked_ip" -j DROP; then
            iptables -A INPUT -s "$blocked_ip" -j DROP
            iptables -A OUTPUT -s "$blocked_ip" -j DROP

            echo "${blocked_ip}" >> "$FIREWALL_DOMAINS"
            save_firewall_settings
        fi
    fi
}

function firewall_unblock_ip {
    blocked_ip="$1"
    if [[ "$blocked_ip" == *'@'* ]]; then
        # Don't try to block email/microblog addresses
        return
    fi
    if grep -q "$blocked_ip" "$FIREWALL_DOMAINS"; then
        iptables -D INPUT -s "$blocked_ip" -j DROP
        iptables -D OUTPUT -s "$blocked_ip" -j DROP

        sed -i "/$blocked_ip/d" "$FIREWALL_DOMAINS"
        echo "${blocked_ip}" >> "$FIREWALL_DOMAINS"
        save_firewall_settings
    fi
}

function firewall_refresh_blocklist {
    if [ ! -f "/root/${PROJECT_NAME}-firewall-domains.cfg" ]; then
        return
    fi

    while read -r blocked_domain; do
        firewall_block_domain "$blocked_domain"
    done <"/root/${PROJECT_NAME}-firewall-domains.cfg"
}

function firewall_unblock_domain {
    unblocked_domain="$1"
    if grep -q "${unblocked_domain}" "$FIREWALL_DOMAINS"; then
        if [[ "${unblocked_domain}" != *'@'* ]]; then
            hexstr=$(domain_to_hex_string "$unblocked_domain")
            iptables -D INPUT -p udp --dport 53 -m string --hex-string "$hexstr" --algo bm -j DROP
            iptables -D INPUT -p tcp --dport 53 -m string --hex-string "$hexstr" --algo bm -j DROP
            iptables -D OUTPUT -p udp --dport 53 -m string --hex-string "$hexstr" --algo bm -j DROP
            iptables -D OUTPUT -p tcp --dport 53 -m string --hex-string "$hexstr" --algo bm -j DROP
            iptables -D FORWARD -p udp --dport 53 -m string --hex-string "$hexstr" --algo bm -j DROP
            iptables -D FORWARD -p tcp --dport 53 -m string --hex-string "$hexstr" --algo bm -j DROP
            save_firewall_settings
        fi
        sed -i "/${unblocked_domain}/d" "$FIREWALL_DOMAINS"
    fi
    if grep -q " $unblocked_domain" /etc/hosts; then
        sed -i "/ $unblocked_domain/d" /etc/hosts
    fi
}

function firewall_drop_spoofed_packets {
    if [[ $(is_completed "${FUNCNAME[0]}") == "1" ]]; then
        return
    fi
    iptables -t mangle -A PREROUTING -s 224.0.0.0/3 -j DROP
    iptables -t mangle -A PREROUTING -s 169.254.0.0/16 -j DROP
    iptables -t mangle -A PREROUTING -s 172.16.0.0/12 -j DROP
    iptables -t mangle -A PREROUTING -s 192.0.2.0/24 -j DROP
    iptables -t mangle -A PREROUTING -s 10.0.0.0/8 -j DROP
    iptables -t mangle -A PREROUTING -s 240.0.0.0/5 -j DROP
    iptables -t mangle -A PREROUTING -s 127.0.0.0/8 ! -i lo -j DROP
    function_check save_firewall_settings
    save_firewall_settings
    mark_completed "${FUNCNAME[0]}"
}

function firewall_rate_limits {
    if [[ $(is_completed "${FUNCNAME[0]}") == "1" ]]; then
        return
    fi

    # Limit connections per source IP
    iptables -A INPUT -p tcp -m connlimit --connlimit-above 111 -j REJECT --reject-with tcp-reset

    # Limit RST packets
    iptables -A INPUT -p tcp --tcp-flags RST RST -m limit --limit 2/s --limit-burst 2 -j ACCEPT
    iptables -A INPUT -p tcp --tcp-flags RST RST -j DROP

    # Limit new TCP connections per second per source IP
    iptables -A INPUT -p tcp -m conntrack --ctstate NEW -m limit --limit 60/s --limit-burst 20 -j ACCEPT
    iptables -A INPUT -p tcp -m conntrack --ctstate NEW -j DROP

    # SSH brute-force protection
    iptables -A INPUT -p tcp --dport ssh -m conntrack --ctstate NEW -m recent --set
    iptables -A INPUT -p tcp --dport ssh -m conntrack --ctstate NEW -m recent --update --seconds 60 --hitcount 10 -j DROP

    function_check save_firewall_settings
    save_firewall_settings
    mark_completed "${FUNCNAME[0]}"
}

# NOTE: deliberately no exit 0