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FreeBSD配置防火墙开启SSH服务的方法

 [ 2017年2月4日 ] 【
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_inter     
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

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#!/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

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