設定ファイル

2.設定ファイル

さて、設定ファイルの編集と動作確認を行うわけですが、これは前ページの状態を標準として１つ１つ動きを確認しながら実施すればよいと思います。
一度にたくさんやろうとすると、どれの設定がおかしいのか分からなくなってしまうからです。
TCP/IPのポート番号表も使いました。

●設定ファイル(/etc/rc.firewall)の準備

FreeBSDをインストール時点で /etc/rc.firewall はあります。
ディフォルトではサンプル記述されています。
とりあえず、cp /etc/rc.firewall /etc/rc.firewall.org としてオリジナルを保存しておきました。
ディフォルトはこんな内容です。

# 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 1.30.2.14 2001/12/28 08:14:42 luigi Exp $ # # # Setup system for firewall service. # # Suck in the configuration variables. if [ -z "${source_rc_confs_defined}" ]; then if [ -r /etc/defaults/rc.conf ]; then . /etc/defaults/rc.conf source_rc_confs elif [ -r /etc/rc.conf ]; then . /etc/rc.conf fi fi ############ # Define the firewall type in /etc/rc.conf. Valid values are: # open - will allow anyone in # client - will try to protect just this machine # simple - will try to protect a whole network # closed - totally disables IP services except via lo0 interface # UNKNOWN - disables the loading of firewall rules. # filename - will load the rules in the given filename (full path required) # # For ``client'' and ``simple'' the entries below should be customized # appropriately. ############ # # If you don't know enough about packet filtering, we suggest that you # take time to read this book: # # Building Internet Firewalls, 2nd Edition # Brent Chapman and Elizabeth Zwicky # # O'Reilly & Associates, Inc # ISBN 1-56592-871-7 # http://www.ora.com/ # http://www.oreilly.com/catalog/fire2/ # # For a more advanced treatment of Internet Security read: # # Firewalls & Internet Security # Repelling the wily hacker # William R. Cheswick, Steven M. Bellowin # # Addison-Wesley # ISBN 0-201-63357-4 # http://www.awl.com/ # http://www.awlonline.com/product/0%2C2627%2C0201633574%2C00.html # if [ -n "${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 ${na td_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 ############ # 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 # Prototype setups. # 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. ############ # set these to your network and netmask and ip net="192.0.2.0" mask="255.255.255.0" ip="192.0.2.1" # 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="ed0" onet="192.0.2.0" omask="255.255.255.240" oip="192.0.2.1" # set these to your inside interface network and netmask and ip iif="ed1" inet="192.0.2.16" imask="255.255.255.240" iip="192.0.2.17" # 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 # 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 ${oip} to any 123 keep-state # Everything else is denied by default, unless the # IPFIREWALL_DEFAULT_TO_ACCEPT option is set in your kernel # config file. ;; [Uu][Nn][Kk][Nn][Oo][Ww][Nn]) ;; *) if [ -r "${firewall_type}" ]; then ${fwcmd} ${firewall_flags} ${firewall_type} fi ;; esac

●設定するネットワーク

●設定ファイル(/etc/rc.firewall)

拙作の設定ファイルは次のようになりました。(/etc/rc.firewall)のルールでは上側の設定が優先されます。
記述後に設定を有効にするには sh /etc/rc.firewall とします。そして ipfw -a list で確認してから実際の動作確認をします。

# # 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 fwcmd="/sbin/ipfw -q" ############ # Flush out the list before we begin. # ${fwcmd} -f flush ############ # set these to your outside interface network and netmask and ip oif="snc0" # 外側のNICです onet="192.168.1.0" # 外側のネットワークアドレスです omask="255.255.255.0" # 外側のサブネットマスクです oip="192.168.1.3" # 外側のNICのIPアドレスです # set these to your inside interface network and netmask and ip iif="fe0" # 内側のNICです inet="192.168.2.0" # 内側のネットワークアドレスです imask="255.255.255.0" # 内側のサブネットマスクです iip="192.168.2.1" # 内側のNICのIPアドレスです www="192.168.2.3" # www(80),FTPサーバー(lavie)のIPアドレス mail="192.168.2.4" # SMTP,POP3サーバー(9801nsa)のIPアドレス win2000="192.168.2.5" # www(8082)サーバー(Windows2000)のIPアドレス www1="192.168.2.7" # www(8081)サーバー(9821ne)のIPアドレス www2="192.168.2.8" # www(8083)サーバー(9821nemail)のIPアドレス # Stop spoofing(IPアドレスなりすましを拒否) ${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 # プライベートアドレスを外に出さないようにします ${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} ↑ # ここはリマーク(ADSLルータでアドレス変換のため) # 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} # Allow TCP through if setup succeeded # 一度確立されたセッションは通すようにします ${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 access to our DNS # DNS参照を通す->DNS設置してないけどね! ${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 setup of incoming email # mailサーバーへのSMTP,POP3を通す ${fwcmd} add pass tcp from any to ${mail} 25 setup ${fwcmd} add pass tcp from any to ${mail} 110 setup ${fwcmd} add pass tcp from any to ${oip} 25 setup # Allow access to our WWW # wwwサーバーへのアクセスを通す ${fwcmd} add pass tcp from any to ${www} 80 setup ${fwcmd} add pass tcp from any to ${www1} 8081 setup ${fwcmd} add pass tcp from any to ${win2000} 8082 setup ${fwcmd} add pass tcp from any to ${www2} 8083 setup # Allow access to our FTP # FTPサーバーへのアクセスを通す ${fwcmd} add pass tcp from any to ${www} 20 setup ${fwcmd} add pass tcp from any to ${www} 21 setup # Reject&Log all setup of incoming connections from the outside # 上記以外は外側からのアクセスを拒否する ${fwcmd} add deny log tcp from any to any in via ${oif} setup # Allow setup of any other TCP connection # TCPのセットアップは通す ${fwcmd} add pass tcp from any to any setup # Allow DNS queries out in the world #DNSクエリを許可 ${fwcmd} add pass udp from any to any 53 ${fwcmd} add pass udp from any 53 to any # Allow NTP queries out in the world #NTPクエリを許可 ${fwcmd} add pass udp from any to any 123 ${fwcmd} add pass udp from any 123 to any # netbios samba # 内側のsambaは自由に使える ${fwcmd} add pass udp from ${inet}:${imask} to ${iip} 137-139,445 via ${iif} ${fwcmd} add pass udp from ${iip} 137-139,445 to ${inet}:${imask} via ${iif} # broad cast # 内側・外側のbroad castは許可する ${fwcmd} add pass udp from ${inet}:${imask} to ${iip} 520 via ${iif} ${fwcmd} add pass udp from ${iip} 520 to ${inet}:${imask} via ${iif} ${fwcmd} add pass udp from ${onet}:${omask} to ${oip} 520 via ${oif} ${fwcmd} add pass udp from ${oip} 520 to ${onet}:${omask} via ${oif} # etc UDP NG # その他のUDPは許可しない ${fwcmd} add deny log udp from any to any # ping # pingに返事を返す ${fwcmd} add pass icmp from any to any via ${iif} ${fwcmd} add pass icmp from any to any out via ${oif} icmptypes 8 ${fwcmd} add pass icmp from any to any in via ${oif} icmptypes 0 ${fwcmd} add pass icmp from any to any in via ${oif} icmptypes 3 # etc NG # その他のICMPは許可しない ${fwcmd} add deny log icmp from any to any

設定にあたっての注意

外部からのアクセスを通すサーバーのIPアドレス設定するとき、サーバー名の最初に数字を使わないこと。
sh /etc/rc.firewall が正常終了しません。一時FireWallの動作がおかしくなります。
[例]

　　1www="192.168.2.3" # www(80),FTPサーバー(lavie)のIPアドレス・・・・・・・・NG
　　www1="192.168.2.3" # www(80),FTPサーバー(lavie)のIPアドレス・・・・・・・・OK

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