Firewall nastaveni

Liquid liquid at liquid.cz
Tue Jul 9 22:31:20 CEST 2002
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Zdravicko.

Mam zkompilovane jadro s podporou FW.
Ted jiz zbyva nastavit rc.conf a rc.firewall.
S tim bych potreboval pomoc. Potrebuju to mit co nejbezpecnejsi. Jednalo by se jen o jeden samotnej server. Zadna sit. Jake zvolit nastaveni? Ukaze mi to nekdo?
A povolit jen WWW, WWWS, FTP, SSH, DNS, MAIL, IMAP/IMAPS.

Pro ukazku mojich dosavadnich konfiguraku.
Muzete je patricne prosim upravit?
Diky Liquid.

------------------------------
rc.conf
------------------------------
hostname="mujserver :-)"
keyrate="fast"
saver="logo"
network_interfaces="fxp0 fxp1 lo0"
ifconfig_fxp0="DHCP"
ifconfig_fxp1="inet 192.168.0.2 netmask 255.255.255.0"
ipv6_enable="YES"
tcp_keepalive="YES"
kern_securelevel="2"
kern_securelevel_enable="YES"
linux_enable="YES"
nfs_server_enable="NO"
sendmail_enable="NO"
sshd_enable="NO"
usbd_enable="NO"
sshd_program="/usr/local/sbin/sshd"
named_enable="YES"
named_program="/usr/sbin/named"

-------------------------------
rc.firewall
------------------------------
# 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 1.30.2.15 2002/02/28 14:51:42 cjc Exp $
#

#
# Setup system for 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
#   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 & Internet Security
# Repelling the wily hacker
# William R. Cheswick, Steven M. Bellowin
#
# Addison-Wesley
# ISBN 0-201-63357-4
# http://www.awl.com/
# http://www.awlonline.com/product/0%2C2627%2C0201633574%2C00.html
#

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
}

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

############
# Flush out the list before we begin.
#
${fwcmd} -f flush

############
# 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.
#
case ${firewall_type} in
[Oo][Pp][Ee][Nn]|[Cc][Ll][Ii][Ee][Nn][Tt])
 case ${natd_enable} in
 [Yy][Ee][Ss])
  if [ -n "${natd_interface}" ]; then
   ${fwcmd} add 50 divert natd all from any to any via ${natd_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.
#
case ${firewall_type} in
[Oo][Pp][Ee][Nn])
 setup_loopback
 ${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.
 ############

 # set these to your network and netmask and ip
 net="192.0.2.0"
 mask="255.255.255.0"
 ip="192.0.2.1"

 setup_loopback

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

 # 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 ${ip} 25 setup

 # Allow setup of outgoing TCP connections only
 ${fwcmd} add pass tcp from ${ip} 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 ${ip} to any 53 keep-state

 # Allow NTP queries out in the world
 ${fwcmd} add pass udp from ${ip} 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 named server and ntp server, and point all the machines
 # on the inside at this machine for those services.
 ############

 # set these to your outside interface network and netmask and ip
 oif="fxp0"

 # set these to your inside interface network and netmask and ip
 iif="fxp1"
 inet="192.168.0.2"
 imask="255.255.255.0"

 setup_loopback

 # Stop spoofing
 ${fwcmd} add deny all from ${inet}:${imask} to any in via ${oif}
 ${fwcmd} add deny all from ${onet}:${omask} 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 ${oip} 25 setup

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

 # Allow access to our WWW
 ${fwcmd} add pass tcp from any to ${oip} 80 setup
 
 # Allow acces to our FTP
 ${fwcmd} add pass tcp from any to ${oip} 21 setup
 
 # Allow acces to our SSH
 #${fwcmd} add pass tcp from any to ${oip} 22 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 ${oip} to any 53 keep-state

 # Allow NTP queries out in the world
 ${fwcmd} add pass udp from ${oip} 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.
 ;;

[Cc][Ll][Oo][Ss][Ee][Dd])
 setup_loopback
 ;;
[Uu][Nn][Kk][Nn][Oo][Ww][Nn])
 ;;
*)
 if [ -r "${firewall_type}" ]; then
  ${fwcmd} ${firewall_flags} ${firewall_type}
 fi
 ;;
esac
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