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Домашняя FreeBSD Образец настройки ipfw.Часть 1

Образец настройки ipfw.Часть 1

Есть две подсети:
подсеть арендаторов и локальная сеть предприятия.
Требуется дать полный доступ арендаторам в сеть предприятия через один IP-адрес
(т.е. с помощью NAT.)

Мы пойдем легким путем.
Будем настраивать конфигурационные файлы rc.conf и rc.firewall.
Особое внимание обратите на выделенное жирным и курсив.
Итак rc.conf:

# -- sysinstall generated deltas -- # Fri Aug 14 14:50:11 2009
# Created: Fri Aug 14 14:50:11 2009
# Enable network daemons for user convenience.
# Please make all changes to this file, not to /etc/defaults/rc.conf.
# This file now contains just the overrides from /etc/defaults/rc.conf.

# Прописываем шлюз по-умолчанию
defaultrouter="10.10.10.243"
# Из сервера делаем шлюз.
gateway_enable="YES"
# Даем имя серверу
hostname="pra.strwi.ru"
# IPADRESS на сетевой карте  для сети Арендаторов
ifconfig_rl0="inet 10.10.50.1  netmask 255.255.255.0"
# IPADRESS на сетевой карте  для локальной сети предприятия.
ifconfig_rl1="inet 10.10.10.61  netmask 255.255.255.0"
# Включаем фаервол.
firewall_enable="YES"
# Задаем тип фаервола Open, т.е разрешено все.
firewall_type="open"
# Включаем NAT
natd_enable="YES"
# Прописываем интерфейс , на который будет найтиться подсеть
natd_interface="rl1"

Начиная с верси FREEBSD 5.X  и выше, при указании опции
firewall_enable="YES", автоматически подзагружается модуль фаервола.
Если версия FreeBSD ниже, необходимо перекомпилить ядро в опциями:
options IPFIREWALL включает код IPFW в ядро.
options IPFIREWALL_VERBOSE - включает протоколирование пакетов.
options IPFIREWALL_VERBOSE_LIMIT=10 - требуется для безопасности от DoS- атаки.
options IPDIVERT - включает код NATD  в ядро.


Теперь рассмотрим файл /etc/rc.firewall :

#!/bin/sh -
# Copyright (c) 1996  Poul-Henning Kamp
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
# $FreeBSD: src/etc/rc.firewall,v 1.52.2.3.4.1 2009/04/15 03:14:26 kensmith Exp $
#

#
# Setup system for ipfw(4) firewall service.
#

# Suck in the configuration variables.
if [ -z "${source_rc_confs_defined}" ]; then
if [ -r /etc/defaults/rc.conf ]; then
. /etc/defaults/rc.conf
source_rc_confs
elif [ -r /etc/rc.conf ]; then
. /etc/rc.conf
fi
fi

############
# Define the firewall type in /etc/rc.conf.  Valid values are:
#   open        - will allow anyone in
#   client      - will try to protect just this machine
#   simple      - will try to protect a whole network
#   closed      - totally disables IP services except via lo0 interface
#   workstation - will try to protect just this machine using statefull
#    firewalling. See below for rc.conf variables used
#   UNKNOWN     - disables the loading of firewall rules.
#   filename    - will load the rules in the given filename (full path required)
#
# For ``client'' and ``simple'' the entries below should be customized
# appropriately.

############
#
# If you don't know enough about packet filtering, we suggest that you
# take time to read this book:
#
# Building Internet Firewalls, 2nd Edition
# Brent Chapman and Elizabeth Zwicky
#
# O'Reilly & Associates, Inc
# ISBN 1-56592-871-7
# http://www.ora.com/
# http://www.oreilly.com/catalog/fire2/
#
# For a more advanced treatment of Internet Security read:
#
# Firewalls and Internet Security: Repelling the Wily Hacker, 2nd Edition
# William R. Cheswick, Steven M. Bellowin, Aviel D. Rubin
#
# Addison-Wesley / Prentice Hall
# ISBN 0-201-63466-X
# http://www.pearsonhighered.com/
#

http://www.pearsonhighered.com/educator/academic/product/0,3110,020163466X,00.html
#
# Автоматическая настройка интерфейса lo.
setup_loopback () {
############
# Only in rare cases do you want to change these rules
#
${fwcmd} add 100 pass all from any to any via lo0
${fwcmd} add 200 deny all from any to 127.0.0.0/8
${fwcmd} add 300 deny ip from 127.0.0.0/8 to any
}

# Считываем тип фаервола. В нашем случае "open"
if [ -n "${1}" ]; then
firewall_type="${1}"
fi

############
# Set quiet mode if requested
#
case ${firewall_quiet} in
[Yy][Ee][Ss])
fwcmd="/sbin/ipfw -q"
;;
*)
fwcmd="/sbin/ipfw"
;;
esac

############ Сбрасываем правила
# Flush out the list before we begin.
#
${fwcmd} -f flush
#Загружаем правила интерфейса lo
setup_loopback

############
# Network Address Translation.  All packets are passed to natd(8)
# before they encounter your remaining rules.  The firewall rules
# will then be run again on each packet after translation by natd
# starting at the rule number following the divert rule.
#
# For ``simple'' firewall type the divert rule should be put to a
# different place to not interfere with address-checking rules.
# Настройка открытого фаервола (наша настройка).
case ${firewall_type} in
[Oo][Pp][Ee][Nn]|[Cc][Ll][Ii][Ee][Nn][Tt])
case ${natd_enable} in
[Yy][Ee][Ss])
# Проверяем включен ли natd_interface в rc.conf, и разрешаем работу
# через NAT интерфейс.


if [ -n "${natd_interface}" ]; then
${fwcmd} add 50 divert natd ip4 from any to any via
${natd_interface}
fi
;;
esac
case ${firewall_nat_enable} in
[Yy][Ee][Ss])
if [ -n "${firewall_nat_interface}" ]; then
if echo "${firewall_nat_interface}" | \
grep -q -E '^[0-9]+(\.[0-9]+){0,3}$'; then
firewall_nat_flags="ip ${firewall_nat_interface}

${firewall_nat_flags}"
else
firewall_nat_flags="if ${firewall_nat_interface}

${firewall_nat_flags}"
fi
${fwcmd} nat 123 config log ${firewall_nat_flags}
${fwcmd} add 50 nat 123 ip4 from any to any via

${firewall_nat_interface}
fi
;;
esac
esac

############
# If you just configured ipfw in the kernel as a tool to solve network
# problems or you just want to disallow some particular kinds of traffic
# then you will want to change the default policy to open.  You can also
# do this as your only action by setting the firewall_type to ``open''.
#
# ${fwcmd} add 65000 pass all from any to any


# Prototype setups.
# Проверяем тип фаервола и разрешаем проходить всему.
case ${firewall_type} in
[Oo][Pp][Ee][Nn])
${fwcmd} add 65000 pass all from any to any
;;

[Cc][Ll][Ii][Ee][Nn][Tt])
############
# This is a prototype setup that will protect your system somewhat
# against people from outside your own network.
#
# Configuration:
#  firewall_client_net:  Network address of local network.
############

# set this to your local network
net="$firewall_client_net"

# Allow any traffic to or from my own net.
${fwcmd} add pass all from me to ${net}
${fwcmd} add pass all from ${net} to me

# Allow TCP through if setup succeeded
${fwcmd} add pass tcp from any to any established

# Allow IP fragments to pass through
${fwcmd} add pass all from any to any frag

# Allow setup of incoming email
${fwcmd} add pass tcp from any to me 25 setup

# Allow setup of outgoing TCP connections only
${fwcmd} add pass tcp from me to any setup

# Disallow setup of all other TCP connections
${fwcmd} add deny tcp from any to any setup

# Allow DNS queries out in the world
${fwcmd} add pass udp from me to any 53 keep-state

# Allow NTP queries out in the world
${fwcmd} add pass udp from me to any 123 keep-state

# Everything else is denied by default, unless the
# IPFIREWALL_DEFAULT_TO_ACCEPT option is set in your kernel
# config file.
;;

[Ss][Ii][Mm][Pp][Ll][Ee])
############
# This is a prototype setup for a simple firewall.  Configure this
# machine as a DNS and NTP server, and point all the machines
# on the inside at this machine for those services.
#
# Configuration:
#  firewall_simple_iif:  Inside network interface.
#  firewall_simple_inet: Inside network address.
#  firewall_simple_oif:  Outside network interface.
#  firewall_simple_onet: Outside network address.
############

# set these to your outside interface network
oif="$firewall_simple_oif"
onet="$firewall_simple_onet"

# set these to your inside interface network
iif="$firewall_simple_iif"
inet="$firewall_simple_inet"

# Stop spoofing
${fwcmd} add deny all from ${inet} to any in via ${oif}
${fwcmd} add deny all from ${onet} to any in via ${iif}

# Stop RFC1918 nets on the outside interface
${fwcmd} add deny all from any to 10.0.0.0/8 via ${oif}
${fwcmd} add deny all from any to 172.16.0.0/12 via ${oif}
${fwcmd} add deny all from any to 192.168.0.0/16 via ${oif}

# Stop draft-manning-dsua-03.txt (1 May 2000) nets (includes RESERVED-1,
# DHCP auto-configuration, NET-TEST, MULTICAST (class D), and class E)
# on the outside interface
${fwcmd} add deny all from any to 0.0.0.0/8 via ${oif}
${fwcmd} add deny all from any to 169.254.0.0/16 via ${oif}
${fwcmd} add deny all from any to 192.0.2.0/24 via ${oif}
${fwcmd} add deny all from any to 224.0.0.0/4 via ${oif}
${fwcmd} add deny all from any to 240.0.0.0/4 via ${oif}

# Network Address Translation.  This rule is placed here deliberately
# so that it does not interfere with the surrounding address-checking
# rules.  If for example one of your internal LAN machines had its IP
# address set to 192.0.2.1 then an incoming packet for it after being
# translated by natd(8) would match the `deny' rule above.  Similarly
# an outgoing packet originated from it before being translated would
# match the `deny' rule below.
case ${natd_enable} in
[Yy][Ee][Ss])
if [ -n "${natd_interface}" ]; then
${fwcmd} add divert natd all from any to any via

${natd_interface}
fi
;;
esac

# Stop RFC1918 nets on the outside interface
${fwcmd} add deny all from 10.0.0.0/8 to any via ${oif}
${fwcmd} add deny all from 172.16.0.0/12 to any via ${oif}
${fwcmd} add deny all from 192.168.0.0/16 to any via ${oif}

# Stop draft-manning-dsua-03.txt (1 May 2000) nets (includes RESERVED-1,
# DHCP auto-configuration, NET-TEST, MULTICAST (class D), and class E)
# on the outside interface
${fwcmd} add deny all from 0.0.0.0/8 to any via ${oif}
${fwcmd} add deny all from 169.254.0.0/16 to any via ${oif}
${fwcmd} add deny all from 192.0.2.0/24 to any via ${oif}
${fwcmd} add deny all from 224.0.0.0/4 to any via ${oif}
${fwcmd} add deny all from 240.0.0.0/4 to any via ${oif}

# Allow TCP through if setup succeeded
${fwcmd} add pass tcp from any to any established

# Allow IP fragments to pass through
${fwcmd} add pass all from any to any frag

# Allow setup of incoming email
${fwcmd} add pass tcp from any to me 25 setup

# Allow access to our DNS
${fwcmd} add pass tcp from any to me 53 setup
${fwcmd} add pass udp from any to me 53
${fwcmd} add pass udp from me 53 to any

# Allow access to our WWW
${fwcmd} add pass tcp from any to me 80 setup

# Reject&Log all setup of incoming connections from the outside
${fwcmd} add deny log tcp from any to any in via ${oif} setup

# Allow setup of any other TCP connection
${fwcmd} add pass tcp from any to any setup

# Allow DNS queries out in the world
${fwcmd} add pass udp from me to any 53 keep-state

# Allow NTP queries out in the world
${fwcmd} add pass udp from me to any 123 keep-state

# Everything else is denied by default, unless the
# IPFIREWALL_DEFAULT_TO_ACCEPT option is set in your kernel
# config file.
;;

[Ww][Oo][Rr][Kk][Ss][Tt][Aa][Tt][Ii][Oo][Nn])
# Configuration:
#  firewall_myservices:  List of TCP ports on which this host
#      offers services.
#  firewall_allowservices: List of IPs which has access to
#     $firewall_myservices.
#  firewall_trusted:  List of IPs which has full access
#     to this host. Be very carefull
#     when setting this. This option can
#     seriously degrade the level of
#     protection provided by the firewall.
#  firewall_logdeny:  Boolean (YES/NO) specifying if the
#     default denied packets should be
#     logged (in /var/log/security).
#  firewall_nologports:  List of TCP/UDP ports for which
#     denied incomming packets are not
#     logged.

# Allow packets for which a state has been built.
${fwcmd} add check-state

# For services permitted below.
${fwcmd} add pass tcp  from me to any established

# Allow any connection out, adding state for each.
${fwcmd} add pass tcp  from me to any setup keep-state
${fwcmd} add pass udp  from me to any       keep-state
${fwcmd} add pass icmp from me to any       keep-state

# Allow DHCP.
${fwcmd} add pass udp  from 0.0.0.0 68 to 255.255.255.255 67 out
${fwcmd} add pass udp  from any 67     to me 68 in
${fwcmd} add pass udp  from any 67     to 255.255.255.255 68 in
# Some servers will ping the IP while trying to decide if it's
# still in use.
${fwcmd} add pass icmp from any to any icmptype 8

# Allow "mandatory" ICMP in.
${fwcmd} add pass icmp from any to any icmptype 3,4,11

# Add permits for this workstations published services below
# Only IPs and nets in firewall_allowservices is allowed in.
# If you really wish to let anyone use services on your
# workstation, then set "firewall_allowservices='any'" in /etc/rc.conf
#
# Note: We don't use keep-state as that would allow DoS of
#       our statetable.
#       You can add 'keep-state' to the lines for slightly
#       better performance if you fell that DoS of your
#       workstation won't be a problem.
#
for i in ${firewall_allowservices} ; do
for j in ${firewall_myservices} ; do
${fwcmd} add pass tcp from $i to me $j
done
done

# Allow all connections from trusted IPs.
# Playing with the content of firewall_trusted could seriously
# degrade the level of protection provided by the firewall.
for i in ${firewall_trusted} ; do
${fwcmd} add pass ip from $i to me
done

${fwcmd} add 65000 count ip from any to any

# Drop packets to ports where we don't want logging
for i in ${firewall_nologports} ; do
${fwcmd} add deny { tcp or udp } from any to any $i in
done

# Broadcasts and muticasts
${fwcmd} add deny ip  from any to 255.255.255.255
${fwcmd} add deny ip  from any to 224.0.0.0/24 in # XXX

# Noise from routers
${fwcmd} add deny udp from any to any 520 in

# Noise from webbrowsing.
# The statefull filter is a bit agressive, and will cause some
#  connection teardowns to be logged.
${fwcmd} add deny tcp from any 80,443 to any 1024-65535 in

# Deny and (if wanted) log the rest unconditionally.
log=""
if [ ${firewall_logdeny:-x} = "YES" -o ${firewall_logdeny:-x} = "yes" ] ;

then
log="log logamount 500" # The default of 100 is too low.
sysctl net.inet.ip.fw.verbose=1 >/dev/null
fi
${fwcmd} add deny $log ip from any to any
;;

[Cc][Ll][Oo][Ss][Ee][Dd])
${fwcmd} add 65000 deny ip from any to any
;;
[Uu][Nn][Kk][Nn][Oo][Ww][Nn])
;;
*)
if [ -r "${firewall_type}" ]; then
${fwcmd} ${firewall_flags} ${firewall_type}
fi
;;
esac

Домашняя FreeBSD Образец настройки ipfw.Часть 1