linux系统firewalld火墙优化策略

一、firewalld

防火墙指的是一个由软件和硬件设备组合而成、在内部网和外部网之间、专用网与公共网之间的界面上构造的保护屏障.是一种获取安全性方法的形象说法，它是一种计算机硬件和软件的结合，使Internet与Intranet之间建立起一个安全网关（Security
Gateway），从而保护内部网免受非法用户的侵入，防火墙主要由服务访问规则、验证工具、包过滤和应用网关4个部分组成，防火墙就是一个位于计算机和它所连接的网络之间的软件或硬件。该计算机流入流出的所有网络通信和数据包均要经过此防火墙。

在网络中，所谓“防火墙”，是指一种将内部网和公众访问网（如Internet）分开的方法，它实际上是一种隔离技术。防火墙是在两个网络通讯时执行的一种访问控制尺度，它能允许你“同意”的人和数据进入你的网络，同时将你“不同意”的人和数据拒之门外，最大限度地阻止网络中的黑客来访问你的网络。换句话说，如果不通过防火墙，公司内部的人就无法访问Internet，Internet上的人也无法和公司内部的人进行通信。

firewalld和iptables的关系

firewalld自身并不具备防火墙的功能，而是和iptables一样需要通过内核的netfilter来实现，也就是说firewalld和iptables一样，他们的作用都是用于维护规则，而真正使用规则干活的是内核的netfilter，只不过firewalld和iptables的结构以及使用方法不一样罢了。

firewalld的配置模式

firewalld的配置文件以xml格式为主（主配置文件firewalld.conf例外），有两个存储位置

1、/etc/firewalld/ 用户配置文件

2、/usr/lib/firewalld/ 系统配置文件，预置文件

 

对于一个接受到的请求具体使用哪个zone，firewalld是通过三种方法来判断的：

1、source，也就是源地址 优先级最高

2、interface，接收请求的网卡 优先级第二

3、firewalld.conf中配置的默认zone 优先级最低

[[email protected] ~]# yum install firewall-config -y

[[email protected] ~]# firewall-config

[[email protected] ~]# yum search iptables

[[email protected] ~]# yum list iptables-services.x86_64

开启 firewalld

[[email protected] ~]# systemctl stop iptables.service
[[email protected] ~]# systemctl disable iptables.service
rm '/etc/systemd/system/basic.target.wants/iptables.service'
[[email protected] ~]# systemctl start firewalld
[[email protected] ~]# systemctl enable firewalld
ln -s '/usr/lib/systemd/system/firewalld.service' '/etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service'

ln -s '/usr/lib/systemd/system/firewalld.service' '/etc/systemd/system/basic.target.wants/firewalld.service'

查看火墙

firewall-cmd –state                                                             #查看火墙当前生效的域
firewall-cmd –get-active-zones                                         #查看默认的域
firewall-cmd –get-default-zone                                          #查看所有的域
firewall-cmd –get-zones                                                     #查看public域里面的信息
firewall-cmd –zone=public –list-all                                    #查看block域里面的信息
firewall-cmd –zone=block –list-all                                     #查看所有域的状态
firewall-cmd –list-all-zones                                                #列出所有域的规则
firewall-cmd –list-all                                                           #列出系统当中用名称代表的服务
firewall-cmd –get-services                                                #打开防火墙界面
firewall-config

测试：

[[email protected] ~]# firewall-cmd --state
running
[[email protected] ~]# firewall-cmd --get-active-zones
ROL
  sources: 172.25.0.252/32
public
  interfaces: eth0
[[email protected] ~]# firewall-cmd --get-default-zone
public
[[email protected] ~]# firewall-cmd --zone=public --list-all
public (default, active)
  interfaces: eth0
  sources:
  services: dhcpv6-client ssh
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:
    
[[email protected] ~]# firewall-cmd --zone=block --list-all
block
  interfaces:
  sources:
  services:
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:
    
[[email protected] ~]# firewall-cmd --list-all
public (default, active)
  interfaces: eth0
  sources:
  services: dhcpv6-client ssh
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:

修改 firewalld 域

修改默认的域为trusted域
firewall-cmd –set-default-zone=trusted
代表可以接收所有网络访问

[[email protected] ~]# yum install httpd -y
[[email protected] ~]# systemctl start httpd

[[email protected] ~]# echo westos> /var/www/html/index.html

浏览器测试：

172.25.254.102

查看不到，因为firewalld域为public

[[email protected] ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth1
[[email protected] ~]# systemctl restart network
[[email protected] ~]# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.25.254.102  netmask 255.255.255.0  broadcast 172.25.254.255
        inet6 fe80::5054:ff:fe00:20a  prefixlen 64  scopeid 0x20<link>
        ether 52:54:00:00:02:0a  txqueuelen 1000  (Ethernet)
        RX packets 46197  bytes 325308296 (310.2 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 29997  bytes 200042107 (190.7 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

eth1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.25.254.202  netmask 255.255.255.0  broadcast 172.25.254.255
        inet6 fe80::5054:ff:fe03:6514  prefixlen 64  scopeid 0x20<link>
        ether 52:54:00:03:65:14  txqueuelen 1000  (Ethernet)
        RX packets 10521  bytes 1144837 (1.0 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 25  bytes 3837 (3.7 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[[email protected] ~]# firewall-cmd --set-default-zone=trusted                                         #修改firewalld域为yrusted
success
[[email protected] ~]# firewall-cmd --get-default-zone
trusted
[[email protected] ~]# firewall-cmd --get-active-zone
ROL
  sources: 172.25.0.252/32
trusted
  interfaces: eth0 eth1
[[email protected] ~]# firewall-cmd --get-services
amanda-client bacula bacula-client dhcp dhcpv6 dhcpv6-client dns ftp high-availability http https imaps ipp ipp-client ipsec kerberos kpasswd ldap ldaps libvirt libvirt-tls mdns mountd ms-wbt mysql nfs ntp openv*n pmcd pmproxy pmwebapi pmwebapis pop3s postgresql proxy-dhcp radius rpc-bind samba samba-client smtp ssh telnet tftp tftp-client transmission-client vnc-server wbem-https
[[email protected] ~]# firewall-cmd --list-all
trusted (default, active)
  interfaces: eth0 eth1
  sources:
  services:
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:

 

浏览器测试：

172.25.254.102

可以看到

使用命令行配置防火墙

设置域为public：

[[email protected] ~]# firewall-cmd --set-default-zone=public

success
[[email protected] ~]# firewall-cmd --list-all
public (default, active)
  interfaces: eth0 eth1
  sources:
  services: dhcpv6-client ssh
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:
    
真机浏览器：172.25.254.102  ：看不到

添加指定ip为trusted：

[[email protected] ~]# firewall-cmd --add-source=172.25.254.2 --zone=trusted

success

只有本机和真机可以看到

[[email protected] ~]# yum install elinks -y

[[email protected] Desktop]# elinks http://172.25.254.102

修改设备状态：

[[email protected] ~]# firewall-cmd --list-interfaces
eth0 eth1
[[email protected] ~]# firewall-cmd --get-zone-of-interface=eth1
public
[[email protected] ~]# firewall-cmd --get-zone-of-interface=eth0
public
[[email protected] ~]# firewall-cmd --change-interface=eth0 --zone=trusted
success
[[email protected] ~]# firewall-cmd --get-zone-of-interface=eth0
trusted
[[email protected] ~]# firewall-cmd --remove-interface=eth0
success
[[email protected] ~]# firewall-cmd --get-zone-of-interface=eth0
no zone
[[email protected] ~]# firewall-cmd --change-interface=eth0 --zone=public
success
[[email protected] ~]# firewall-cmd --get-zone-of-interface=eth0
public

永久添加主机域，重启后不会消失：

[[email protected] ~]# firewall-cmd --permanent --add-source=172.25.254.2
success
[[email protected] ~]# firewall-cmd --reload
success
[[email protected] ~]# firewall-cmd --list-all
public (default, active)
  interfaces: eth0 eth1
  sources: 172.25.254.2
  services: dhcpv6-client ssh
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:
    

添加指定服务

[[email protected] ~]# cd /etc/firewalld

[[email protected] firewalld]# ls
firewalld.conf  firewalld.conf.old  icmptypes  lockdown-whitelist.xml  services  zones
[[email protected] firewalld]# cd zones
[[email protected] zones]# ls
public.xml  public.xml.old  ROL.xml
[[email protected] zones]# vim public.xml                                                          #编辑firewalld规则文件

  8   <service name="http"/>                                                                       #添加http服务

[[email protected] zones]# systemctl restart firewalld
[[email protected] zones]# firewall-cmd --list
usage: see firewall-cmd man page
firewall-cmd: error: ambiguous option: --list could match --list-lockdown-whitelist-contexts, --list-all, --list-lockdown-whitelist-uids, --list-ports, --list-forward-ports, --list-icmp-blocks, --list-interfaces, --list-rich-rules, --list-services, --list-lockdown-whitelist-commands, --list-all-zones, --list-sources, --list-lockdown-whitelist-users
[[email protected] zones]# firewall-cmd --list-all
public (default, active)
  interfaces: eth0 eth1
  sources: 172.25.254.2
  services: dhcpv6-client http ssh
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:
    

[[email protected] zones]# cd /usr/lib/firewalld
[[email protected] firewalld]# ls
icmptypes  services  zones
[[email protected] firewalld]# cd services
[[email protected] services]# vim http.xml

修改端口：

[[email protected] services]# cd
[[email protected] ~]# firewall-cmd --add-port=8080/tcp --zone=public
success
[[email protected] ~]# firewall-cmd --list-all
public (default, active)
  interfaces: eth0 eth1
  sources: 172.25.254.2
  services: dhcpv6-client http ssh
  ports: 8080/tcp
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:

  

临时移除防火墙允许服务：

[[email protected] ~]# firewall-cmd --remove-service=ssh
success


[[email protected] Desktop]# ssh [email protected]                                                #无法连接虚拟机
ssh: connect to host 172.25.254.102 port 22: No route to host

恢复：

[[email protected] services]# cd
[[email protected] ~]# firewall-cmd --add-port=8080/tcp --zone=public
success
[[email protected] ~]# firewall-cmd --list-all
public (default, active)
  interfaces: eth0 eth1
  sources: 172.25.254.2
  services: dhcpv6-client http ssh
  ports: 8080/tcp
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:

 

 

永久移除防火墙允许服务：

[[email protected] ~]# firewall-cmd --remove-service=ssh
success
[[email protected] ~]# firewall-cmd --reload
success
[[email protected] ~]# firewall-cmd --list-all
public (default, active)
  interfaces: eth0 eth1
  sources: 172.25.254.2
  services: dhcpv6-client http ssh
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:
    
[[email protected] ~]# firewall-cmd --permanent --remove-service=ssh
success
[[email protected] ~]# firewall-cmd --list-all
public (default, active)
  interfaces: eth0 eth1
  sources: 172.25.254.2
  services: dhcpv6-client http ssh
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:
    

[[email protected] ~]# firewall-cmd --complete-reload

当永久删除firewlld允许的ssh服务时 firewall-cmd –reload 与firewall-cmd –complete-reload 重新加载的区别：

在真机连接到服务主机之后
使用 firewall-cmd –reload 重新加载时，不会断开连接，可以进行操作
使用 firewall-cmd –complete-reload 重新加载时，会中断连接，不能进行操作

Direct Rules

三表：
filter：访问本机数据，过滤，防火墙（包含input、output、forword）
nat：从本机经过的数据，网络地址转换（包含output、prerouting、postrouting）
mangle：（包含input、output、postrouting、prerouting、forward）
五链：
input：目的地址为本机
output：原地址为本机，向外发送
forward：实现转发
postrouting：数据包进入路由之后
prerouting；数据包进入路由之前三表：
filter：访问本机数据，过滤，防火墙（包含input、output、forword）
nat：从本机经过的数据，网络地址转换（包含output、prerouting、postrouting）
mangle：（包含input、output、postrouting、prerouting、forward）
五链：
input：目的地址为本机
output：原地址为本机，向外发送
forward：实现转发
postrouting：数据包进入路由之后
prerouting；数据包进入路由之前三表：

filter：访问本机数据，过滤，防火墙（包含input、output、forword）
nat：从本机经过的数据，网络地址转换（包含output、prerouting、postrouting）
mangle：（包含input、output、postrouting、prerouting、forward）
五链：
input：目的地址为本机
output：原地址为本机，向外发送
forward：实现转发
postrouting：数据包进入路由之后
prerouting；数据包进入路由之前

当http加入firewalld允许访问的列表里面，所有主机都可以访问，这是不安全的，应该对个别主机设定访问权限，以保证安全

1.允许指定ip访问指定服务

[[email protected] ~]# firewall-cmd --list-all                                                          #查看火墙的设定信息
[[email protected] ~]# yum install httpd -y
[[email protected] ~]# systemctl start httpd
[[email protected] ~]# firewall-cmd --list-all
public (default, active)
  interfaces: eth0
  sources:
  services: dhcpv6-client ssh
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:
    
[[email protected] ~]# firewall-cmd --permanent --add-service=http                   #永久允许访问http服务
success
[[email protected] ~]# firewall-cmd --reload                                                           #刷新
success

[[email protected] ~]# firewall-cmd --list-all                                                            #查看已加入

public (default, active)
  interfaces: eth0
  sources:
  services: dhcpv6-client http ssh
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:
  rich rules:

在真机和server浏览器：
172.25.254.102
可以看到http测试界面

2、对个别主机设定访问权限

测试：

[[email protected] ~]# firewall-cmd --permanent --remove-service=http                   #永久禁止访问http服务

success

[[email protected] ~]# firewall-cmd --reload
success

刷新浏览器，两个都不能查看


[[email protected] ~]# firewall-cmd --list-all
public (default, active)
  interfaces: eth0
  sources:
  services: dhcpv6-client ssh
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:

  rich rules:

实验：

[[email protected] ~]# iptables -nL                                               #查看filter表信息

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0            ctstate RELATED,ESTABLISHED
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0           
INPUT_direct  all  --  0.0.0.0/0            0.0.0.0/0           
INPUT_ZONES_SOURCE  all  --  0.0.0.0/0            0.0.0.0/0           
INPUT_ZONES  all  --  0.0.0.0/0            0.0.0.0/0           
ACCEPT     icmp --  0.0.0.0/0            0.0.0.0/0           
REJECT     all  --  0.0.0.0/0            0.0.0.0/0            reject-with icmp-host-prohibited

禁止访问应该设置input
       
[[email protected] ~]# firewall-cmd --direct --add-rule ipv4 filter INPUT 1 -p tcp --dport 80 -s 172.25.254.202 -j ACCEPT
success

#--direct   添加规则  ipv4   协议方式 filter 表 INPUT 链 -p 链 --dport 目的地 -s 数据来源  -j 动作（REJECT 有回应的拒绝，DROP 拒绝后没有回显，ACCEPT 接收 ）
拒绝一般用REJECT


[[email protected] ~]# firewall-cmd --direct --get-all-rules
ipv4 filter INPUT 1 -p tcp --dport 80 -s 172.25.254.202 -j ACCEPT


浏览器测试：
真机无法查看，server可以

端口转发

当别人访问这台主机时，却连接的是另一台主机

测试：
[[email protected] Desktop]$ ssh [email protected] -X
[email protected]'s password:
Last login: Fri Jun  8 21:20:55 2018 from 172.25.254.2
[[email protected] ~]# ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.25.254.102  netmask 255.255.255.0  broadcast 172.25.254.255
        inet6 fe80::5054:ff:fe00:20a  prefixlen 64  scopeid 0x20<link>
        ether 52:54:00:00:02:0a  txqueuelen 1000  (Ethernet)
        RX packets 27767  bytes 8748266 (8.3 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1911  bytes 261245 (255.1 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

[[email protected] ~]# firewall-cmd --list-all
public (default, active)
  interfaces: eth0
  sources:
  services: dhcpv6-client ssh
  ports:
  masquerade: no
  forward-ports:
  icmp-blocks:

  rich rules:

实验：

  

[[email protected] ~]# firewall-cmd --permanent --add-forward-port=port=22:proto=tcp:toport=22:toaddr=172.25.254.202
success
    
[[email protected] ~]# firewall-cmd --reload
success
[[email protected] ~]# firewall-cmd --list-all
public (default, active)
  interfaces: eth0
  sources:
  services: dhcpv6-client ssh
  ports:
  masquerade: no
  forward-ports: port=22:proto=tcp:toport=22:toaddr=172.25.254.202
  icmp-blocks:
  rich rules:
    
[[email protected] ~]# firewall-cmd --permanent --add-masquerade                                #永久开启masquerade服务
success
[[email protected] ~]# firewall-cmd --reload
success
[[email protected] ~]# firewall-cmd --list-all
public (default, active)
  interfaces: eth0
  sources:
  services: dhcpv6-client ssh
  ports:
  masquerade: yes
  forward-ports: port=22:proto=tcp:toport=22:toaddr=172.25.254.202
  icmp-blocks:
  rich rules:



测试：

[[email protected] Desktop]$ ssh [email protected]
[email protected]'s password:
Last login: Fri Jun  8 23:02:19 2018 from 172.25.254.102
[[email protected] ~]# ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 172.25.254.202  netmask 255.255.255.0  broadcast 172.25.254.255
        inet6 fe80::5054:ff:fe00:20b  prefixlen 64  scopeid 0x20<link>
        ether 52:54:00:00:02:0b  txqueuelen 1000  (Ethernet)
        RX packets 66175  bytes 579744521 (552.8 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 38019  bytes 2666875 (2.5 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

访问172.25.254.102，却连接的是172.25.254.202这台主机

地址伪装

在添加地址伪装的主机添加两块网卡并设置不同网段的ip

在desktop虚拟机添加另一个网段的ip：

[[email protected] ~]# cd /etc/sysconfig/network-scripts/
[[email protected] network-scripts]# ls
ifcfg-eth0   ifdown-ppp       ifup-eth     ifup-sit
ifcfg-lo     ifdown-routes    ifup-ippp    ifup-Team
ifdown       ifdown-sit       ifup-ipv6    ifup-TeamPort
ifdown-bnep  ifdown-Team      ifup-isdn    ifup-tunnel
ifdown-eth   ifdown-TeamPort  ifup-plip    ifup-wireless
ifdown-ippp  ifdown-tunnel    ifup-plusb   init.ipv6-global
ifdown-ipv6  ifup             ifup-post    network-functions
ifdown-isdn  ifup-aliases     ifup-ppp     network-functions-ipv6
ifdown-post  ifup-bnep        ifup-routes
[[email protected] network-scripts]# cp ifcfg-eth0 ifcfg-eth1
[[email protected] network-scripts]# vim ifcfg-eth1

DEVICE=eth1
TYPE=Ethernet
BOOTPROTO=none
IPADDR0=172.25.0.102
NETMASK=255.255.255.0
USERCTL=yes
PEERDNS=yes
IPV6INIT=no
ONBOOT=yes
PERSISTENT_DHCLIENT=1


[[email protected] network-scripts]# systemctl restart network


将server虚拟机ip设置为与desktop虚拟机eth1同网段，网关设置为desktop虚拟机eth1的ip
[[email protected] ~]# vim /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0
TYPE=Ethernet
BOOTPROTO=none
IPADDR0=172.25.0.202
GATEWAY=172.25.0.102
NETMASK=255.255.255.0
USERCTL=yes
PEERDNS=yes
IPV6INIT=no
ONBOOT=yes
PERSISTENT_DHCLIENT=1

[[email protected] ~]# systemctl restart network

在desktop虚拟机：

[[email protected] network-scripts]#firewalld-cmd --permanent --remove-forward-port=port=22:proto=22:toaddr=172.25.254.102

                                                                                                                   #永久删除伪装的ip端口

[[email protected] network-scripts]# sysctl -a |grep ip_forward

net.ipv4.ip_forward = 0
[[email protected] network-scripts]# vim /etc/sysctl.conf


  5 net.ipv4.ip_forward = 1

[[email protected] network-scripts]# sysctl -p                                              #加载文件参数
net.ipv4.ip_forward = 1