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| -rw-r--r-- | setup2hd/SeTfirewall.tpl | 704 |
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diff --git a/setup2hd/SeTfirewall.tpl b/setup2hd/SeTfirewall.tpl new file mode 100644 index 0000000..144794f --- /dev/null +++ b/setup2hd/SeTfirewall.tpl @@ -0,0 +1,704 @@ +#!/bin/bash + +# ------------------------------------------------------------------------------ +# Configure a basic firewall, +# by generating a set of iptables rules (ipv4 and ipv6), +# and saving those to /etc/firewall/ipv4 and /etc/firewall/ipv6 . +# The accompanying script /etc/rc.d/rc.firewall will restore these configs. +# +# This script and rc.firewall are part of liveslak, +# a project by Eric Hameleers, see https://download.liveslak.org/ +# +# Iptables ruleset handling courtesy of Easy Firewall Generator for IPTables, +# Copyright 2002 Timothy Scott Morizot +# ------------------------------------------------------------------------------ + +# The script accepts one parameter: the target filesystem: +DESTDIR="$1" + +# This tmp directory is only writable by root: +TMP=${TMP:-"/var/log/setup/tmp"} +if [ ! -d $TMP ]; then + mkdir -p $TMP +fi + +# The script defaults to curses dialog but Xdialog is a good alternative: +DIALOG=${DIALOG:-"dialog"} + +# The iptables tools we use: +IPT="/usr/sbin/iptables" +IP6T="/usr/sbin/ip6tables" +IPTS="/usr/sbin/iptables-save" +IP6TS="/usr/sbin/ip6tables-save" +IPTR="/usr/sbin/iptables-restore" +IP6TR="/usr/sbin/ip6tables-restore" + +# Localhost Interface +LO_IFACE="lo" +LO_IP="127.0.0.1" +LO_IP6="::1" + +# The default gateway device will be our primary candidate to firewall: +GWDEV=$(/sbin/ip route show |grep ^default |cut -d' ' -f5) + +# Generate a list of network devices, minus the default gateway and loopback: +AVAILDEV=$(ls --indicator-style=none /sys/class/net/ |sed -e "s/${GWDEV}//" -e "s/lo//") + +# Store all network interfaces in an associative array: +declare -A NETDEVARR +NETDEVARR=( [$GWDEV]=on ) +for INDEV in $AVAILDEV ; do NETDEVARR+=( [$INDEV]=off ) ; done +unset INDEV + +# Store network services in another array: +declare -A SERVARR=( + ['SSH']=off + ['RSYNC']=off + ['GIT']=off + ['HTTP']=off + ['HTTPS']=off + ['SMTP']=off + ['SMPTS']=off + ['IMAP']=off + ['IMAPS']=off + ['NTP']=off +) + +# Store the list of custom ports/port ranges: +CUSTOM_TCP_LIST="" +CUSTOM_UDP_LIST="" + +# Will we auto-configure a restrictive firewall? +AUTOCONFIG="YES" + +# User pressing ESC will change the default choice in the 1st dialog: +DEFAULTNO="" + +# Loop over the configuration until the user is done: +MAINSELECT="start" +while [ "$MAINSELECT" != "done" ]; do + if [ "$MAINSELECT" = "start" ]; then + ${DIALOG} --backtitle "@UDISTRO@ (@LIVEDE@) Basic Firewall Setup" \ + --title "CONFIGURE FIREWALL" ${DEFAULTNO} \ + --yesno "Would you like to protect the system with a basic firewall?\n\n\ +You can either block all external connections, +or you can expose specific TCP/UDP ports.\n\n\ +DHCP will never be blocked." 11 68 + if [ $? != 0 ]; then + # Not needed. + exit 0 + else + DEFAULTNO="" + fi + MAINSELECT="devices" + fi + + if [ "$MAINSELECT" = "devices" ]; then + # Populate the network device checklist for the dialog: + NETDEVLIST="$(for I in ${!NETDEVARR[@]};do echo $I ${NETDEVARR[$I]};done)" + unset I + ${DIALOG} --backtitle "@UDISTRO@ (@LIVEDE@) Basic Firewall Setup" \ + --title "PICK INTERFACES" \ + --stdout --separate-output \ + --no-items \ + --ok-label "Next" --no-cancel --extra-button --extra-label "Previous" \ + --checklist "\ +Select the network interface(s) exposed to the outside world.\n\ +Your default gateway is pre-selected.\n\ +Un-selected interfaces will accept all incoming traffic." 13 68 5 $NETDEVLIST \ + > $TMP/SeTnics + RETVAL=$? + # Zero out the array values and re-enable only the ones we got returned: + for INDEV in ${!NETDEVARR[@]} ; do NETDEVARR[$INDEV]=off ; done + for INDEV in $(cat $TMP/SeTnics) ; do NETDEVARR[$INDEV]=on ; done + unset INDEV + case "$RETVAL" in + 0) MAINSELECT="autoselect" ;; + 3) MAINSELECT="start" ;; + *) MAINSELECT="start" ; DEFAULTNO="--defaultno" ;; + esac + rm -f $TMP/SeTnics + fi + + if [ "$MAINSELECT" = "autoselect" ]; then + ${DIALOG} --backtitle "@UDISTRO@ (@LIVEDE@) Basic Firewall Setup" \ + --title "ALL CLOSED?" \ + --yesno "Do you want to block all incoming external connections?\n\ +If 'no', then you will be able to specify ports that need to be open." 7 68 + RETVAL=$? + case "$RETVAL" in + 0) AUTOCONFIG="YES" + MAINSELECT="done" ;; + 1) AUTOCONFIG="NO" + MAINSELECT="services" ;; + *) MAINSELECT="start" ; DEFAULTNO="--defaultno" ;; + esac + fi + + if [ "$MAINSELECT" = "services" ]; then + # Populate the services checklist for the dialog: + ${DIALOG} --backtitle "@UDISTRO@ (@LIVEDE@) Basic Firewall Setup" \ + --title "OPEN PORTS" \ + --stdout --separate-output \ + --ok-label "Next" --no-cancel --extra-button --extra-label "Previous" \ + --checklist "\ +Select the service ports you want to remain open for the outside world.\n\ +You can enter more ports or portranges in the next dialog." 19 68 13 \ +SSH 'SSH (port 22)' ${SERVARR['SSH']} \ +RSYNC 'RSYNC (port 873)' ${SERVARR['RSYNC']} \ +GIT 'GIT (port 9418)' ${SERVARR['GIT']} \ +HTTP 'Web Server (HTTP port 80)' ${SERVARR['HTTP']} \ +HTTPS 'Secure Web Server (HTTPS port 443)' ${SERVARR['HTTPS']} \ +SMTP 'Receiving Email (SMTP port 25)' ${SERVARR['SMTP']} \ +SMTPS 'Secure Receiving Email (SMPTS port 587)' ${SERVARR['SMPTS']} \ +IMAP 'IMAP Email Server (IMAP port 143)' ${SERVARR['IMAP']} \ +IMAPS 'Secure IMAP Email Server (IMAPS port 993)' ${SERVARR['IMAPS']} \ +NTP 'Time Server (NTP port 123)' ${SERVARR['NTP']} \ + > $TMP/SeTservices + RETVAL=$? + # Zero out the array values and re-enable only the ones we got returned: + for INSRV in ${!SERVARR[@]} ; do SERVARR[$INSRV]=off ; done + for INSRV in $(cat $TMP/SeTservices) ; do SERVARR[$INSRV]=on ; done + unset INSRV + case $RETVAL in + 0) MAINSELECT="customports" ;; + 3) MAINSELECT="autoselect" ;; + *) MAINSELECT="start" ; DEFAULTNO="--defaultno" ;; + esac + rm -f $TMP/SeTservices + fi + + if [ "$MAINSELECT" = "customports" ]; then + ${DIALOG} --backtitle "@UDISTRO@ (@LIVEDE@) Basic Firewall Setup" \ + --title "CUSTOM PORTS" \ + --stdout \ + --ok-label "Next" --no-cancel --extra-button --extra-label "Previous" \ + --form "\ +Enter additional ports or port ranges.\n\ +Port ranges consist of two numbers separated by a colon (example: 3000:3011).\n\ +Separate multiple entries with commas,\n\ +for example: 22,465,3000:3011,6660:6669,7000" \ +13 68 2 \ +"TCP ports/portranges:" 1 1 "$CUSTOM_TCP_LIST" 1 25 40 0 \ +"UDP ports/portranges:" 2 1 "$CUSTOM_UDP_LIST" 2 25 40 0 \ + > $TMP/SeTcustomports + RETVAL=$? + CUSTOM_TCP_LIST=$(head -1 $TMP/SeTcustomports) + CUSTOM_UDP_LIST=$(tail -1 $TMP/SeTcustomports) + case $RETVAL in + 0) MAINSELECT="confirm" ;; + 3) MAINSELECT="services" ;; + *) MAINSELECT="start" ; DEFAULTNO="--defaultno" ;; + esac + rm -f $TMP/SeTcustomports + fi + + if [ "$MAINSELECT" = "confirm" ]; then + # Collect all service ports that need to be remotely accessible. + # TCP: + TCP_LIST="" + if [ "${SERVARR['HTTP']}" = "on" ]; then + TCP_LIST="$TCP_LIST 80" + fi + if [ "${SERVARR['HTTPS']}" = "on" ]; then + TCP_LIST="$TCP_LIST 443" + fi + if [ "${SERVARR['SMTP']}" = "on" ]; then + TCP_LIST="$TCP_LIST 25" + fi + if [ "${SERVARR['SMTPS']}" = "on" ]; then + TCP_LIST="$TCP_LIST 587" + fi + if [ "${SERVARR['IMAP']}" = "on" ]; then + TCP_LIST="$TCP_LIST 143" + fi + if [ "${SERVARR['IMAPS']}" = "on" ]; then + TCP_LIST="$TCP_LIST 993" + fi + if [ "${SERVARR['SSH']}" = "on" ]; then + TCP_LIST="$TCP_LIST 22" + fi + if [ "${SERVARR['GIT']}" = "on" ]; then + TCP_LIST="$TCP_LIST 9418" + fi + if [ "${SERVARR['RSYNC']}" = "on" ]; then + TCP_LIST="$TCP_LIST 873" + fi + TCP_LIST=$(echo $TCP_LIST | sed 's/^ *//g' | tr ' ' ',') + # UDP: + UDP_LIST="" + if [ "${SERVARR['NTP']}" = "on" ]; then + UDP_LIST="$UDP_LIST 123" + fi + if [ "${SERVARR['RSYNC']}" = "on" ]; then + UDP_LIST="$UDP_LIST 873" + fi + UDP_LIST=$(echo $UDP_LIST | sed 's/^ *//g' | tr ' ' ',') + + TCP_LIST=$(echo $TCP_LIST $CUSTOM_TCP_LIST | sed 's/^ *//g' | tr ' ' ',') + UDP_LIST=$(echo $UDP_LIST $CUSTOM_UDP_LIST | sed 's/^ *//g' | tr ' ' ',') + DEV_LIST=$(for INDEV in ${!NETDEVARR[@]} ; do if [ "${NETDEVARR[$INDEV]}" = "on" ]; then echo -n $INDEV ; fi ; done) + + ${DIALOG} --backtitle "@UDISTRO@ (@LIVEDE@) Basic Firewall Setup" \ + --title "CONFIRM CONFIGURATION" \ + --yes-label "Generate" --no-label "Redo" \ + --yesno "These are the ports you configured. Are you OK with them?\n\n\ +Press 'Generate' to generate the firewall configuration.\n\ +Else press 'Redo' to re-do the setup.\n\n\ +Firewalled interface(s): $DEV_LIST \n\ +TCP Ports: $TCP_LIST \n\ +UDP Ports: $UDP_LIST" 12 68 + RETVAL=$? + case $RETVAL in + 0) MAINSELECT="done" ;; + 1) MAINSELECT="devices" ;; + *) MAINSELECT="start" ; DEFAULTNO="--defaultno" ;; + esac + fi + +done + +# ------------------------------------------------------------------------------ +# End of configuration, let's get to work. +# ------------------------------------------------------------------------------ + +# +# Flush Any Existing Rules or Chains +# + +${DIALOG} --backtitle "@UDISTRO@ (@LIVEDE@) Basic Firewall Setup" \ + --infobox "Configuring your firewall ..." 4 68 + +# Reset Default Policies +$IPT -P INPUT ACCEPT +$IPT -P FORWARD ACCEPT +$IPT -P OUTPUT ACCEPT +$IPT -t nat -P PREROUTING ACCEPT +$IPT -t nat -P POSTROUTING ACCEPT +$IPT -t nat -P OUTPUT ACCEPT +$IPT -t mangle -P PREROUTING ACCEPT +$IPT -t mangle -P OUTPUT ACCEPT +# +$IP6T -P INPUT ACCEPT +$IP6T -P FORWARD ACCEPT +$IP6T -P OUTPUT ACCEPT +$IP6T -t mangle -P PREROUTING ACCEPT +$IP6T -t mangle -P OUTPUT ACCEPT + +# Flush all rules +$IPT -F +$IPT -t nat -F +$IPT -t mangle -F +# +$IP6T -F +$IP6T -t mangle -F + +# Erase all non-default chains +$IPT -X +$IPT -t nat -X +$IPT -t mangle -X +# +$IP6T -X +$IP6T -t mangle -X + +# +# Rules Configuration +# +# Filter Table +# + +# Set Policies +$IPT -P INPUT DROP +$IPT -P OUTPUT DROP +$IPT -P FORWARD DROP +# +$IP6T -P INPUT DROP +$IP6T -P OUTPUT DROP +$IP6T -P FORWARD DROP + +# +# User-Specified Chains +# +# Create user chains to reduce the number of rules each packet must traverse. +# + +# Create a chain to filter INVALID packets +$IPT -N bad_packets +$IP6T -N bad_packets + +# Create another chain to filter bad tcp packets +$IPT -N bad_tcp_packets +$IP6T -N bad_tcp_packets + +# Create separate chains for icmp, tcp (incoming and outgoing), +# and incoming udp packets. +$IPT -N icmp_packets +$IP6T -N icmp_packets + +# Used for UDP packets inbound from the Internet +$IPT -N udp_inbound +$IP6T -N udp_inbound + +# Used to block outbound UDP services from internal network +# Default to allow all +$IPT -N udp_outbound +$IP6T -N udp_outbound + +# Used to allow inbound services if desired +# Default fail except for established sessions +$IPT -N tcp_inbound +$IP6T -N tcp_inbound + +# Used to block outbound services from internal network +# Default to allow all +$IPT -N tcp_outbound +$IP6T -N tcp_outbound + +# +# Populate User Chains +# +# bad_packets chain +# + +# Drop INVALID packets immediately +$IPT -A bad_packets -p ALL -m state --state INVALID -j DROP +$IP6T -A bad_packets -p ALL -m state --state INVALID -j DROP + +# Then check the tcp packets for additional problems +$IPT -A bad_packets -p tcp -j bad_tcp_packets +$IP6T -A bad_packets -p tcp -j bad_tcp_packets + +# All good, so return +$IPT -A bad_packets -p ALL -j RETURN +$IP6T -A bad_packets -p ALL -j RETURN + +# bad_tcp_packets chain +# +# All tcp packets will traverse this chain. +# Every new connection attempt should begin with +# a syn packet. If it doesn't, it is likely a +# port scan. This drops packets in state +# NEW that are not flagged as syn packets. +$IPT -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j DROP +$IP6T -A bad_tcp_packets -p tcp ! --syn -m state --state NEW -j DROP +$IPT -A bad_tcp_packets -p tcp --tcp-flags ALL NONE -j DROP +$IP6T -A bad_tcp_packets -p tcp --tcp-flags ALL NONE -j DROP +$IPT -A bad_tcp_packets -p tcp --tcp-flags ALL ALL -j DROP +$IP6T -A bad_tcp_packets -p tcp --tcp-flags ALL ALL -j DROP +$IPT -A bad_tcp_packets -p tcp --tcp-flags ALL FIN,URG,PSH -j DROP +$IP6T -A bad_tcp_packets -p tcp --tcp-flags ALL FIN,URG,PSH -j DROP +$IPT -A bad_tcp_packets -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP +$IP6T -A bad_tcp_packets -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP +$IPT -A bad_tcp_packets -p tcp --tcp-flags SYN,RST SYN,RST -j DROP +$IP6T -A bad_tcp_packets -p tcp --tcp-flags SYN,RST SYN,RST -j DROP +$IPT -A bad_tcp_packets -p tcp --tcp-flags SYN,FIN SYN,FIN -j DROP +$IP6T -A bad_tcp_packets -p tcp --tcp-flags SYN,FIN SYN,FIN -j DROP + +# All good, so return +$IPT -A bad_tcp_packets -p tcp -j RETURN +$IP6T -A bad_tcp_packets -p tcp -j RETURN + +# icmp_packets chain +# +# This chain is for inbound (from the Internet) icmp packets only. +# Type 8 (Echo Request) is not accepted by default +# Enable it if you want remote hosts to be able to reach you. +# 11 (Time Exceeded) is the only one accepted +# that would not already be covered by the established +# connection rule. Applied to INPUT on the external interface. +# +# See: http://www.ee.siue.edu/~rwalden/networking/icmp.html +# for more info on ICMP types. +# +# Note that the stateful settings allow replies to ICMP packets. +# These rules allow new packets of the specified types. + +# ICMP packets should fit in a Layer 2 frame, thus they should +# never be fragmented. Fragmented ICMP packets are a typical sign +# of a denial of service attack. +$IPT -A icmp_packets --fragment -p icmp -j DROP +$IP6T -A icmp_packets -p ipv6-icmp -m ipv6header --header frag --soft -j DROP + +# Echo - uncomment to allow your system to be pinged. +# $IPT -A icmp_packets -p icmp -s 0/0 --icmp-type 8 -j ACCEPT +# $IP6T -A icmp_packets -p ipv6-icmp -s 0/0 --icmpv6-type 8 -j ACCEPT + +# By default, however, drop pings without logging. Blaster +# and other worms have infected systems blasting pings. +# Comment the line below if you want pings logged, but it +# will likely fill your logs. +$IPT -A icmp_packets -p icmp -s 0/0 --icmp-type 8 -j DROP +$IP6T -A icmp_packets -p ipv6-icmp -s 0/0 --icmpv6-type 8 -j DROP + +# Time Exceeded +$IPT -A icmp_packets -p icmp -s 0/0 --icmp-type 11 -j ACCEPT +$IP6T -A icmp_packets -p ipv6-icmp -s 0/0 --icmpv6-type 11 -j ACCEPT + +# Not matched, so return so it will be logged +$IPT -A icmp_packets -p icmp -j RETURN +$IP6T -A icmp_packets -p ipv6-icmp -j RETURN + +# TCP & UDP +# Identify ports at: +# http://www.chebucto.ns.ca/~rakerman/port-table.html +# http://www.iana.org/assignments/port-numbers + +# udp_inbound chain +# +# This chain describes the inbound UDP packets it will accept. +# It's applied to INPUT on the external or Internet interface. +# Note that the stateful settings allow replies. +# These rules are for new requests. +# It drops netbios packets (windows) immediately without logging. + +# Drop netbios calls +# Please note that these rules do not really change the way the firewall +# treats netbios connections. Connections from the localhost and +# internal interface (if one exists) are accepted by default. +# Responses from the Internet to requests initiated by or through +# the firewall are also accepted by default. To get here, the +# packets would have to be part of a new request received by the +# Internet interface. You would have to manually add rules to +# accept these. I added these rules because some network connections, +# such as those via cable modems, tend to be filled with noise from +# unprotected Windows machines. These rules drop those packets +# quickly and without logging them. This prevents them from traversing +# the whole chain and keeps the log from getting cluttered with +# chatter from Windows systems. +$IPT -A udp_inbound -p udp -s 0/0 --dport 137 -j DROP +$IPT -A udp_inbound -p udp -s 0/0 --dport 138 -j DROP +$IP6T -A udp_inbound -p udp -s 0/0 --dport 137 -j DROP +$IP6T -A udp_inbound -p udp -s 0/0 --dport 138 -j DROP + +# Ident requests (Port 113) must have a REJECT rule rather than the +# default DROP rule. This is the minimum requirement to avoid +# long delays while connecting. Also see the tcp_inbound rule. +$IPT -A udp_inbound -p udp -s 0/0 --dport 113 -j REJECT +$IP6T -A udp_inbound -p udp -s 0/0 --dport 113 -j REJECT + +# A more sophisticated configuration could accept the ident requests. +# $IPT -A udp_inbound -p udp -s 0/0 --dport 113 -j ACCEPT +# $IP6T -A udp_inbound -p udp -s 0/0 --dport 113 -j ACCEPT + +# IPv4 only: +# Allow DHCP client request packets inbound from external network +$IPT -A udp_inbound -p udp -s 0/0 --source-port 68 --dport 67 \ + -j ACCEPT +# Dynamic Address +# If DHCP, the initial request is a broadcast. The response +# doesn't exactly match the outbound packet. This explicitly +# allow the DHCP ports to alleviate this problem. +# If you receive your dynamic address by a different means, you +# can probably comment this line. +$IPT -A udp_inbound -p udp -s 0/0 --source-port 67 --dport 68 \ + -j ACCEPT + +# Open the custom UDP ports if they have been configured: +if [ -n "$UDP_LIST" ]; then + $IPT -A INPUT -p udp -m multiport --dport $UDP_LIST -j ACCEPT + $IP6T -A INPUT -p udp -m multiport --dport $UDP_LIST -j ACCEPT +fi + +# Not matched, so return for logging +$IPT -A udp_inbound -p udp -j RETURN +$IP6T -A udp_inbound -p udp -j RETURN + +# udp_outbound chain +# +# This chain is used with a private network to prevent forwarding for +# UDP requests on specific protocols. Applied to the FORWARD rule from +# the internal network. Ends with an ACCEPT + + +# No match, so ACCEPT +$IPT -A udp_outbound -p udp -s 0/0 -j ACCEPT +$IP6T -A udp_outbound -p udp -s 0/0 -j ACCEPT + +# tcp_inbound chain +# +# This chain is used to allow inbound connections to the +# system/gateway. Use with care. It defaults to none. +# It's applied on INPUT from the external or Internet interface. + +# Ident requests (Port 113) must have a REJECT rule rather than the +# default DROP rule. This is the minimum requirement to avoid +# long delays while connecting. Also see the tcp_inbound rule. +$IPT -A tcp_inbound -p tcp -s 0/0 --dport 113 -j REJECT +$IP6T -A tcp_inbound -p tcp -s 0/0 --dport 113 -j REJECT + +# A more sophisticated configuration could accept the ident requests. +# $IPT -A tcp_inbound -p tcp -s 0/0 --dport 113 -j ACCEPT +# $IP6T -A tcp_inbound -p tcp -s 0/0 --dport 113 -j ACCEPT + +# Open the requested TCP service ports if they have been configured: +if [ -n "$TCP_LIST" ]; then + $IPT -A INPUT -p tcp -m multiport --dport $TCP_LIST -j ACCEPT + $IP6T -A INPUT -p tcp -m multiport --dport $TCP_LIST -j ACCEPT +fi + +# Not matched, so return so it will be logged +$IPT -A tcp_inbound -p tcp -j RETURN +$IP6T -A tcp_inbound -p tcp -j RETURN + +# tcp_outbound chain +# +# This chain is used with a private network to prevent forwarding for +# requests on specific protocols. Applied to the FORWARD rule from +# the internal network. Ends with an ACCEPT + +# No match, so ACCEPT +$IPT -A tcp_outbound -p tcp -s 0/0 -j ACCEPT +$IP6T -A tcp_outbound -p tcp -s 0/0 -j ACCEPT + +# +# INPUT Chain +# +# Allow all on localhost interface +$IPT -A INPUT -p ALL -i $LO_IFACE -j ACCEPT +$IP6T -A INPUT -p ALL -i $LO_IFACE -j ACCEPT + +# Allow all on other internal interfaces: +for INDEV in ${!NETDEVARR[@]} ; do + if [ "${NETDEVARR[$INDEV]}" = "off" ] ; then + $IPT -A INPUT -p ALL -i $INDEV -j ACCEPT + $IP6T -A INPUT -p ALL -i $INDEV -j ACCEPT + fi +done +unset INDEV + +# Drop bad packets +$IPT -A INPUT -p ALL -j bad_packets +$IP6T -A INPUT -p ALL -j bad_packets + +# DOCSIS compliant cable modems +# Some DOCSIS compliant cable modems send IGMP multicasts to find +# connected PCs. The multicast packets have the destination address +# 224.0.0.1. You can accept them. If you choose to do so, +# Uncomment the rule to ACCEPT them and comment the rule to DROP +# them The firewall will drop them here by default to avoid +# cluttering the log. The firewall will drop all multicasts +# to the entire subnet (224.0.0.1) by default. To only affect +# IGMP multicasts, change '-p ALL' to '-p 2'. Of course, +# if they aren't accepted elsewhere, it will only ensure that +# multicasts on other protocols are logged. +# Drop them without logging. +$IPT -A INPUT -p ALL -d 224.0.0.1 -j DROP +# The rule to accept the packets. +# $IPT -A INPUT -p ALL -d 224.0.0.1 -j ACCEPT + +# Inbound Internet Packet Rules + +for INDEV in ${!NETDEVARR[@]} ; do + if [ "${NETDEVARR[$INDEV]}" = "on" ] ; then + # Accept Established Connections + $IPT -A INPUT -p ALL -i $INDEV -m state --state ESTABLISHED,RELATED \ + -j ACCEPT + $IP6T -A INPUT -p ALL -i $INDEV -m state --state ESTABLISHED,RELATED \ + -j ACCEPT + + # Route the rest to the appropriate user chain + $IPT -A INPUT -p tcp -i $INDEV -j tcp_inbound + $IP6T -A INPUT -p tcp -i $INDEV -j tcp_inbound + $IPT -A INPUT -p udp -i $INDEV -j udp_inbound + $IP6T -A INPUT -p udp -i $INDEV -j udp_inbound + $IPT -A INPUT -p icmp -i $INDEV -j icmp_packets + $IP6T -A INPUT -p ipv6-icmp -i $INDEV -j icmp_packets + fi +done +unset INDEV + +# Drop without logging broadcasts that get this far. +# Cuts down on log clutter. +# Comment this line if testing new rules that impact +# broadcast protocols. +$IPT -A INPUT -m pkttype --pkt-type broadcast -j DROP +$IP6T -A INPUT -m pkttype --pkt-type broadcast -j DROP + +# Log packets that still don't match +$IPT -A INPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \ + --log-prefix "INPUT packet died: " +$IP6T -A INPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \ + --log-prefix "INPUT packet ipv6 died: " + +# +# FORWARD Chain +# +# Used if forwarding for a private network + +# +# OUTPUT Chain +# +# Generally trust the firewall on output + +# However, invalid icmp packets need to be dropped +# to prevent a possible exploit. +$IPT -A OUTPUT -m state -p icmp --state INVALID -j DROP +$IP6T -A OUTPUT -m state -p ipv6-icmp --state INVALID -j DROP + +# Localhost +$IPT -A OUTPUT -p ALL -s $LO_IP -j ACCEPT +$IP6T -A OUTPUT -p ALL -s $LO_IP6 -j ACCEPT +$IPT -A OUTPUT -p ALL -o $LO_IFACE -j ACCEPT +$IP6T -A OUTPUT -p ALL -o $LO_IFACE -j ACCEPT + +# Allow all on other internal interfaces: +for OUTDEV in ${!NETDEVARR[@]} ; do + if [ "${NETDEVARR[$OUTDEV]}" = "off" ] ; then + $IPT -A OUTPUT -p ALL -o $OUTDEV -j ACCEPT + $IP6T -A OUTPUT -p ALL -o $OUTDEV -j ACCEPT + fi +done +unset OUTDEV + +# To internet +for OUTDEV in ${!NETDEVARR[@]} ; do + if [ "${NETDEVARR[$OUTDEV]}" = "on" ] ; then + $IPT -A OUTPUT -p ALL -o $OUTDEV -j ACCEPT + $IP6T -A OUTPUT -p ALL -o $OUTDEV -j ACCEPT + fi +done + +# Log packets that still don't match +$IPT -A OUTPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \ + --log-prefix "OUTPUT packet died: " +$IP6T -A OUTPUT -m limit --limit 3/minute --limit-burst 3 -j LOG \ + --log-prefix "OUTPUT packet ipv6 died: " + +# +# nat table +# +# The nat table is where network address translation occurs if there +# is a private network. If the gateway is connected to the Internet +# with a static IP, snat is used. If the gateway has a dynamic address, +# masquerade must be used instead. There is more overhead associated +# with masquerade, so snat is better when it can be used. +# The nat table has a builtin chain, PREROUTING, for dnat and redirects. +# Another, POSTROUTING, handles snat and masquerade. + +# +# PREROUTING chain +# + +# +# POSTROUTING chain +# + + +# +# mangle table +# +# The mangle table is used to alter packets. It can alter or mangle them in +# several ways. For the purposes of this generator, we only use its ability +# to alter the TTL in packets. However, it can be used to set netfilter +# mark values on specific packets. Those marks could then be used in another +# table like filter, to limit activities associated with a specific host, for +# instance. The TOS target can be used to set the Type of Service field in +# the IP header. Note that the TTL target might not be included in the +# distribution on your system. If it is not and you require it, you will +# have to add it. That may require that you build from source. + +# Save the firewall configuration so that 'rc.firewall' can load it: +mkdir -p $DESTDIR/etc/firewall +${IPTS} > $DESTDIR/etc/firewall/ipv4 +${IP6TS} > $DESTDIR/etc/firewall/ipv6 + |