FreeBSDファイアーウォールおよびSSHサービス起動の方法
1.FreeBSDファイアーウォールの設定
(1).
ee /etc/rc.conf #
(2).
firewall_enable="yes" #ファイアーウォール有効
net.inet.ip.fw.verbose=1 #ファイアーウォールログ有効
net.inet.ip.fw.verbose_limit=5 #同上
natd_enable="YES" # ファイアーウォールNAT機能有効
natd_interface="rl0″
natd_flags="-dynamic -m"
firewall_script="/etc/ipfw.rules" #ファイアーウォールのルールパス
(3).ESCを押し、Enter,aキーを押して保存
2.ファイアーウォールのルールの追加
(1).ee /etc/ipfw.rules
(2).下記コードを追加
#!/bin/sh
################ Start of IPFW rules file ######################
# Flush out the list before we begin.
ipfw -q -f flush
# Set rules command prefix
cmd="ipfw -q add"
skip="skipto 800″
pif="rl0″ # public interface name of NIC
# facing the public Internet
#################################################################
# No restrictions on Inside LAN Interface for private network
# Change xl0 to your LAN NIC interface name
#################################################################
$cmd 005 allow all from any to any via xl0
#################################################################
# No restrictions on Loopback Interface
#################################################################
$cmd 010 allow all from any to any via lo0
#################################################################
# check if packet is inbound and nat address if it is
#################################################################
$cmd 014 divert natd ip from any to any in via $pif
#################################################################
# Allow the packet through if it has previous been added to the
# the “dynamic" rules table by a allow keep-state statement.
#################################################################
$cmd 015 check-state
#################################################################
# Interface facing Public Internet (Outbound Section)
# Check session start requests originating from behind the
# firewall on the private network or from this gateway server
# destined for the public Internet.
#################################################################
# Allow out access to my ISP’s Domain name server.
# x.x.x.x must be the IP address of your ISP’s DNS
# Dup these lines if your ISP has more than one DNS server
# Get the IP addresses from /etc/resolv.conf file
$cmd 020 $skip tcp from any to x.x.x.x 53 out via $pif setup keep-state
# Allow out access to my ISP’s DHCP server for cable/DSL configurations.
$cmd 030 $skip udp from any to x.x.x.x 67 out via $pif keep-state
# Allow out non-secure standard www function
$cmd 040 $skip tcp from any to any 80 out via $pif setup keep-state
# Allow out secure www function https over TLS SSL
$cmd 050 $skip tcp from any to any 443 out via $pif setup keep-state
# Allow out send & get email function
$cmd 060 $skip tcp from any to any 25 out via $pif setup keep-state
$cmd 061 $skip tcp from any to any 110 out via $pif setup keep-state
# Allow out FreeBSD (make install & CVSUP) functions
# Basically give user root “GOD" privileges.
$cmd 070 $skip tcp from me to any out via $pif setup keep-state uid root
# Allow out ping
$cmd 080 $skip icmp from any to any out via $pif keep-state
# Allow out Time
$cmd 090 $skip tcp from any to any 37 out via $pif setup keep-state
# Allow out nntp news (i.e. news groups)
$cmd 100 $skip tcp from any to any 119 out via $pif setup keep-state
# Allow out secure FTP, Telnet, and SCP
# This function is using SSH (secure shell)
$cmd 110 $skip tcp from any to any 22 out via $pif setup keep-state
# Allow out whois
$cmd 120 $skip tcp from any to any 43 out via $pif setup keep-state
# Allow ntp time server
$cmd 130 $skip udp from any to any 123 out via $pif keep-state
#################################################################
# Interface facing Public Internet (Inbound Section)
# Check packets originating from the public Internet
# destined for this gateway server or the private network.
#################################################################
# Deny all inbound traffic from non-routable reserved address spaces
#$cmd 300 deny all from 192.168.0.0/16 to any in via $pif #RFC 1918 private IP
$cmd 301 deny all from 172.16.0.0/12 to any in via $pif #RFC 1918 private IP
$cmd 302 deny all from 10.0.0.0/8 to any in via $pif #RFC 1918 private IP
$cmd 303 deny all from 127.0.0.0/8 to any in via $pif #loopback
$cmd 304 deny all from 0.0.0.0/8 to any in via $pif #loopback
$cmd 305 deny all from 169.254.0.0/16 to any in via $pif #DHCP auto-config
$cmd 306 deny all from 192.0.2.0/24 to any in via $pif #reserved for docs
$cmd 307 deny all from 204.152.64.0/23 to any in via $pif #Sun cluster
$cmd 308 deny all from 224.0.0.0/3 to any in via $pif #Class D & E multicast
# Deny ident
$cmd 315 deny tcp from any to any 113 in via $pif
# Deny all Netbios service. 137=name, 138=datagram, 139=session
# Netbios is MS/Windows sharing services.
# Block MS/Windows hosts2 name server requests 81
$cmd 320 deny tcp from any to any 137 in via $pif
$cmd 321 deny tcp from any to any 138 in via $pif
$cmd 322 deny tcp from any to any 139 in via $pif
$cmd 323 deny tcp from any to any 81 in via $pif
# Deny any late arriving packets
$cmd 330 deny all from any to any frag in via $pif
# Deny ACK packets that did not match the dynamic rule table
$cmd 332 deny tcp from any to any established in via $pif
# Allow traffic in from ISP’s DHCP server. This rule must contain
# the IP address of your ISP’s DHCP server as it’s the only
# authorized source to send this packet type.
# Only necessary for cable or DSL configurations.
# This rule is not needed for 'user ppp’ type connection to
# the public Internet. This is the same IP address you captured
# and used in the outbound section.
$cmd 360 allow udp from x.x.x.x to any 68 in via $pif keep-state
# Allow in standard www function because I have Apache server
$cmd 370 allow tcp from any to me 80 in via $pif setup limit src-addr 2
# Allow in secure FTP, Telnet, and SCP from public Internet
$cmd 380 allow tcp from any to me 22 in via $pif setup limit src-addr 2
# Allow in non-secure Telnet session from public Internet
# labeled non-secure because ID & PW are passed over public
# Internet as clear text.
# Delete this sample group if you do not have telnet server enabled.
$cmd 390 allow tcp from any to me 23 in via $pif setup limit src-addr 2
# Reject & Log all unauthorized incoming connections from the public Internet
$cmd 400 deny log all from any to any in via $pif
# Reject & Log all unauthorized out going connections to the public Internet
$cmd 450 deny log all from any to any out via $pif
# This is skipto location for outbound stateful rules
$cmd 800 divert natd ip from any to any out via $pif
$cmd 801 allow ip from any to any
# Everything else is denied by default
# deny and log all packets that fell through to see what they are
$cmd 999 deny log all from any to any
################ End of IPFW rules file ###############################
3.ファイアウォールが有効になるようにネットワークサービスを再起動
/etc/netstart #ネットワークサービスを再起動
/etc/rc.d/ipfw start #ファイアウォールを起動
ipfw disable firewall #ファイアウォールを停止
ipfw enable firewall #ファイアウォール有効
/etc/rc.d/ipfw restart #ファイアウォールが再起動
sh /etc/ipfw.rules #ファイアウォールのルール有効
4.SSHサービスが再起動
(1).ee /etc/inetd.xonf ＃sshdの先頭#を削除
ssh stream tcp nowait root /usr/sbin/sshd sshd -i -4
(2).ee /etc/rc.conf #最後に下記行目が追加される
sshd_enable="yes"
(3).ee /etc/ssh/sshd_config #構成ファイルを編集
PermitRootLogin yes #rootログインを許可
PasswordAuthentication yes #パスワード認証を使用
PermitEmptyPasswords no #空のパスワードを許可しない
/etc/rc.d/sshd start #sshサービスが起動
/etc/rc.d/sshd restart #sshが再起動