FreeBSD ipfw 防火墙基础指南

王朝system·作者佚名  2006-11-23
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一、内核配置

/usr/src/sys/i386/conf/HQ_SuperServer

代码: options IPFIREWALL

options IPFIREWALL_DEFAULT_TO_ACCEPT

options IPDIVERT # IPDIVERT enables the divert IP sockets, used by ''ipfw divert''

options IPFIREWALL_VERBOSE

options IPFIREWALL_VERBOSE_LIMIT=30

#options IPFILTER #ipfilter support

#options IPFILTER_LOG #ipfilter logging

# traffic shaper, bandwidth manager and delay emulator

options DUMMYNET # enables the "dummynet" bandwidth limiter. You need IPFIREWALL as well.

# Statically Link in accept filters for a web server on this box

options ACCEPT_FILTER_DATA

options ACCEPT_FILTER_HTTP

options ICMP_BANDLIM # D.O.S. protection

options IPSTEALTH #To hide firewall from traceroute

options TCP_DROP_SYNFIN #To hide from nmap OS fingerprint, remove if create web server

二、rc.conf配置

/etc/rc.conf

代码: firewall_enable="YES"

firewall_logging="YES"

firewall_script="/etc/rc.firewall"

firewall_quiet="NO" #change to YES once happy with rules

firewall_logging_enable="YES"

#extra firewalling options

log_in_vain="YES"

#This option prevents something known as OS fingerprinting, must have TCP_DROP_SYNFIN compiled into kernel to use

tcp_drop_synfin="NO" #change to NO if create webserver

tcp_restrict_rst="YES"

icmp_drop_redirect="YES"

三、ipfw使用

代码: ipfw add allow tcp from to in recv

添加和除去规则例子:

代码: $ sudo ipfw add deny tcp from 61.49.203.115 to 61.49.203.114 22 in recv fxp0

$ sudo ipfw -t list

$ sudo ipfw delete 00100

禁止icmp

代码: $ sudo ipfw add deny icmp from any to any in recv fxp0

显示rules

代码: $ sudo ipfw show

按照序号显示规则

代码: $ sudo ipfw -t list

列出信息包的数目,和与它们相对应的规则匹配

代码: $ sudo ipfw -a list

四、/etc/ipfw.rules规则文件

代码: allow 00010 udp from any to me 67 in via $iif

allow 00020 udp from me 68 to any out via $iif

五、/etc/rc.firewall脚本

代码: # mv /etc/rc.firewall /etc/rc.firewall.orig

# touch /etc/rc.firewall

# chmod u=+rx,og=-rwx /etc/ipfw.rules

/etc/rc.firewall

代码: #!/bin/sh

# This will flush the existing rules - sudo ipfw -f flush

# You can execute this script without dropping existing connections/states

fwcmd="/sbin/ipfw -q"

extif="fxp0"

myip="10.1.8.114"

mybcast="10.1.8.119"

mynetwork="10.1.8.112/29"

dns_server="10.1.8.1"

# Reset all rules in case script run multiple times

${fwcmd} -f flush

${fwcmd} add 200 check-state

# Block RFC 1918 networks - the , syntax only works in ipfw2

${fwcmd} add 210 deny all from 0.0.0.0/7,1.0.0.0/8,2.0.0.0/8,5.0.0.0/8,10.0.0.0/8,23.0.0.0/8,\

27.0.0.0/8,31.0.0.0/8,67.0.0.0/8,68.0.0.0/6,72.0.0.0/5,80.0.0.0/4,96.0.0.0/3,127.0.0.0/8,\

128.0.0.0/16,128.66.0.0/16,169.254.0.0/16,172.16.0.0/12,191.255.0.0/16,192.0.0.0/16,\

192.168.0.0/16,197.0.0.0/8,201.0.0.0/8,204.152.64.0/23,224.0.0.0/3,240.0.0.0/8 to any

# Allow all via loopback to loopback

${fwcmd} add 220 allow all from any to any via lo0

# Allow from me to anywhere

${fwcmd} add 240 allow tcp from ${myip} to any setup keep-state

${fwcmd} add 260 allow udp from ${myip} to any keep-state

${fwcmd} add 280 allow icmp from ${myip} to any

# Allow local LAN to connect to us

${fwcmd} add 300 allow ip from ${mynetwork} to ${mynetwork}

# Allow INCOMING SSH,SMTP,HTTP from anywhere on the internet

${fwcmd} add 320 allow log tcp from any to ${myip} 22,25,80 in keep-state setup

# Disable icmp

${fwcmd} add 340 allow icmp from any to any icmptype 0,3,11

# Block all other traffic and log in

${fwcmd} add 360 deny log all from any to any

# End of /etc/rc.firewall

六、 ipfw日志纪录配置

/etc/syslog.conf

代码: !ipfw

*.* /var/log/ipfw.log

代码: $ sudo touch /var/log/ipfw.log

$ sudo killall -HUP syslogd

 
 
 
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