FreeBSD ipfw设置

一、开机启动IPFW防火墙
ee /etc/rc.conf
加入以下代码：
firewall_type="open"

/* firewall_type说明

firewall_type="open"
    从/etc/rc.firewall或包含规则集的文件中的防火墙类型中指定防火墙类型。 /etc/rc.firewall中可选的防火墙类型为：
    open－不限制IP访问；closed－禁止除通过lo0进行的之外的所有IP服务； client－对工作站的基本保护；simple－对LAN
    的基本保护。如果给的是一个指定的文件名，则必须使用全路径名

firewall_script="/etc/ipfw.rules" // ipfw.rules 是防火墙规则文件

firewall_quiet="NO" // 启用脚本时，是否显示规则信息；假如你的防火墙脚本已经不会再有修改，那么就可以把这里设置成“YES”了。

firewall_logging="YES"

二、建立防火墙规则
ee /etc/ipfw.rules

三、Ipfw命令

1、使用规则
    # ipfw show
    65535 5294 820413 allow ip from any to any
    ＃ipfw add 10001 deny all from 10.5.3.70 to any
    # ipfw show
    10001    0      0 deny ip from 10.5.3.70 to any
    65535 5673 854504 allow ip from any to any

2、保存规则
    # ee /etc/rc.firewall
    查找到open
    添加ipfw add 10001 deny all from 10.5.3.70 to any
    # sh /etc/rc.firewall all （生效）
    Flushed all rules.
    10001 deny ip from 10.5.3.70 to any

    或
    # /etc/netstart
    # ipfw show
    10001    0      0 deny ip from 10.5.3.70 to any
    65535 6712 791642 allow ip from any to any

3、ipfw命令
    按顺序列出所有的规则：
    # ipfw list

    列出所有的规则，同时给出最后一次匹配的时间戳：
    # ipfw -t list

    列出所有的记账信息、匹配规则的包的数量，以及规则本身。第一列是规则的编号，随后是发出包匹配的数量，进入
    包的匹配数量，最后是规则本身。
    # ipfw -a list

    列出所有的动态规则和静态规则：
    # ipfw -d list

    同时显示已过期的动态规则：
    # ipfw -d -e list

    将计数器清零：
    # ipfw zero

    只把规则号为 NUM 的计数器清零：
    # ipfw zero NUM

四、Ipfw规则集

规则集是一组根据包中选择的数值使用 allow 或 deny 写出的 ipfw 规则。在两个主机之前的双向包交换组成了一次会
    话交互。防火墙规则集，会对同一个包处理两次：第一次是包从公网上到达防火墙时，而第二次则是包返回 Internet
    公网上的主机时。每一个 TCP/IP 服务 (例如 telnet, www, mail, 等等)，都有事先定义好的协议，以及一个端口号。
    这可以作为建立允许或阻止规则时的基本选择依据。当有数据包进入防火墙时，会从规则集里的第一个规则开始进行比较，
    并自顶向下地进行匹配。当包与某个选择规则参数相匹配时，将会执行规则所定义的动作，并停止规则集搜索。这种策
    略，通常也被称作 “最先匹配者获胜” 的搜索方法。如果没有任何与包相匹配的规则，那么它就会根据强制的 ipfw默
    认规则，也就是 65535 号规则截获。一般情况下这个规则是阻止包，而且不给出任何回应。

    注意: 如果规则定义的动作是 count、 skipto 或 tee 规则的话，搜索会继续。这里所介绍的规则，都是使用了那些包
          含状态功能的，也就是 'keep state'、 'limit'、 'in'/'out'、或者 'via' 选项的规则。这是编写包容式防火
          墙规则集所需的基本框架。包容式防火墙只允许与规则匹配的包通过。这样，您就既能够控制来自防火墙后面的机器
          请求 Internet 公网上的那些服务，同时也可以控制来自 Internet 的请求能够访问内部网上的哪些服务。所有其它
          的访问请求都会被阻止，并记录下来。包容式防火墙一般而言要远比排斥式的要安全，而且也只需要定义允许哪些访
          问通过。
    警告: 在操作防火墙规则时应谨慎行事，如果操作不当，有可能将自己反锁在外面。

#################################################
# ipfw Firewall Commands
#################################################
cmd="ipfw -q add"
ipfw -q -f flush
pif="em0"

#################################################
# Allow Loopback and Deny Loopback Spoofing
#################################################
$cmd allow all from any to any via lo0
$cmd deny all from any to 127.0.0.0/8
$cmd deny all from 127.0.0.0/8 to any
$cmd deny tcp from any to any frag

#################################################
# Stateful rules
#################################################
$cmd check-state
$cmd deny tcp from any to any established
$cmd allow all from any to any out keep-state //开放本机访问Internet主要是为了放行web服务
$cmd allow icmp from any to any

#################################################
# Table 10 for IP blocks
#################################################
ipfw -q table 10 add 127.0.0.2
ipfw -q add 900 deny ip from 'table(10)' to any

#################################################
# Incoming/Outgoing Services
#################################################
$cmd 60001 allow tcp from any to any 21 setup limit src-addr 10
$cmd 60002 allow tcp from any to any 22 setup limit src-addr 8
$cmd 60003 allow tcp from any to any 25 setup limit src-addr 10
$cmd 60004 allow tcp from any to any 587 setup limit src-addr 20
$cmd 60005 allow tcp from any to any 53 setup limit src-addr 3
$cmd 60006 allow udp from any to any 53 limit src-addr 3
$cmd 60007 allow tcp from any to any 80 setup limit src-addr 20
$cmd 60008 allow tcp from any to any 110 setup limit src-addr 20
$cmd 60009 allow tcp from any to any 143 setup limit src-addr 10
$cmd 60010 allow tcp from any to any 443 setup limit src-addr 10
$cmd 60011 allow tcp from any to any 2222 setup limit src-addr 12
$cmd 60012 allow tcp from any to any 35000-35999 in setup limit src-addr 10
$cmd 60013 allow tcp from any to any 993 setup limit src-addr 10
$cmd 60014 allow tcp from any to any 995 setup limit src-addr 10
$cmd 60015 allow tcp from any to any 465 setup limit src-addr 10
$cmd 60016 allow tcp from any to any 585 setup limit src-addr 10

#################################################
# Deny Port scanning (Nmap)
#################################################
$cmd 00600 deny log logamount 50 ip from any to any ipoptions rr
$cmd 00610 deny log logamount 50 ip from any to any ipoptions ts
$cmd 00620 deny log logamount 50 ip from any to any ipoptions lsrr
$cmd 00630 deny log logamount 50 ip from any to any ipoptions ssrr
$cmd 00640 deny log logamount 50 tcp from any to any tcpflags syn,fin
$cmd 00650 deny log logamount 50 tcp from any to any tcpflags syn,rst

#################################################
# Deny and Log
#################################################
$cmd deny log all from any to any

扩展

1、配置FreeBSD 防火墙
ee /etc/rc.conf   #编辑，在最后添加
firewall_enable="yes" #开启防火墙
net.inet.ip.fw.verbose=1   #启用防火墙日志功能
net.inet.ip.fw.verbose_limit=5 #启用防火墙日志功能
natd_enable="YES" # 开启防火墙NAT功能
natd_interface="rl0"
natd_flags="-dynamic -m"
firewall_script="/etc/ipfw.rules"      #自定义防火墙规则路径
按esc，回车，再按a保存配置
2、添加防火墙规则

ee /etc/ipfw.rules    #编辑防火墙规则，添加以下代码

#!/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 ###############################

  

备注：参数说明：
#$cmd 300 deny all from 192.168.0.0/16 to any in via $pif #RFC 1918 private IP
我的IP地址是192.168.21.173，是属于192.168.0.0/16 IP段，所以这里要注释掉这一行，允许连接外网，否则主机无法联网。
$cmd 380 allow tcp from any to me 22 in via $pif setup limit src-addr 2
是开启SSH默认端口22
3、重启网络服务，使防火墙规则生效
系统运维 www.osyunwei.com 温馨提醒：qihang01原创内容版权所有,转载请注明出处及原文链接
/etc/netstart #重启网络
/etc/rc.d/ipfw start    #开启防火墙
ipfw disable firewall    #关闭防火墙
ipfw enable firewall   #开启防火墙
/etc/rc.d/ipfw restart #重启防火墙
sh /etc/ipfw.rules     #使防火墙规则生效
4、开启SSH服务
（1）ee /etc/inetd.conf #编辑，去掉sshd前面的#
ssh     stream tcp     nowait root    /usr/sbin/sshd          sshd -i -4
（2）ee /etc/rc.conf   #编辑，在最后添加
sshd_enable="yes"
（3）ee /etc/ssh/sshd_config #编辑配置文件
PermitRootLogin yes   #允许root登录
PasswordAuthentication yes    #使用密码验证
PermitEmptyPasswords no   #不允许空密码登录
/etc/rc.d/sshd start #启动ssh服务
/etc/rc.d/sshd restart    #重启ssh
配置完成，现在已经可以使用Putty等远程连接工具连接服务器了。
#####################################################
扩展阅读：
有两种加载自定义 ipfw 防火墙规则的方法。
其一是将变量 firewall_type 设为包含不带 ipfw(8) 命令行选项的防火墙规则文件的完整路径。
例如：
add allow in
add allow out
firewall_type="open"参数说明
open ── 允许所有流量通过。
client ── 只保护本机。
simple ── 保护整个网络。
closed ── 完全禁止除回环设备之外的全部 IP 流量。
UNKNOWN ── 禁止加载防火墙规则。
filename ── 到防火墙规则文件的绝对路径。
IPFW防火墙规则集样例在这两个文件中
/etc/rc.firewall
/etc/rc.firewall6
除此之外，也可以将 firewall_script 变量设为包含 ipfw 命令的可执行脚本，这样这个脚本会在启动时自动执行。
#####################################################

posted @ 2016-11-29 15:54 冰封的心阅读(2416) 评论(0) 收藏举报

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