FreeBSD ipfw 防火牆基礎指南(轉)

FreeBSD ipfw 防火牆基礎指南(轉)[@more@]

FreeBSD ipfw 防火牆基礎指南 (zt)

FreeBSD ipfw 防火牆基礎指南

轉自: http://w.yi.org/weblog/42_0_1_0.html

FreeBSD ipfw 防火牆基礎指南

本文告訴你如何快速上手FreeBSD的IPFW防火牆

一、核心配置

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

程式碼:

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

程式碼:

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

程式碼:

ipfw add allow tcp from to in recv

新增和除去規則例子：

程式碼:

$ 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

程式碼:

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

顯示rules

程式碼:

$ sudo ipfw show

按照序號顯示規則

程式碼:

$ sudo ipfw -t list

列出資訊包的數目，和與它們相對應的規則匹配

程式碼:

$ sudo ipfw -a list

四、/etc/ipfw.rules規則檔案

程式碼:

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指令碼

程式碼:

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

# touch /etc/rc.firewall

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

/etc/rc.firewall

程式碼:

#!/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日誌紀錄配置

/etc/syslog.conf

程式碼:

!ipfw

*.* /var/log/ipfw.log

程式碼:

$ sudo touch /var/log/ipfw.log

$ sudo killall -HUP syslog