10.11 Linux网络相关 10.12 firewalld和netfilter 10.13 netfilter5表5链介绍 10.14 iptables语法

[root@lizhipeng01 ~]# ifconfig -a
eno16777736: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.5.128 netmask 255.255.255.0 broadcast 192.168.5.255
inet6 fe80::20c:29ff:fe7e:1a2f prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:7e:1a:2f txqueuelen 1000 (Ethernet)
RX packets 90296 bytes 35206086 (33.5 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 306605 bytes 78269419 (74.6 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

[root@lizhipeng01 ~]# cd /etc/sysconfig/network-scripts/
[root@lizhipeng01 network-scripts]# ls
ifcfg-eno16777736 ifdown-eth ifdown-isdn ifdown-sit ifup ifup-ib ifup-plip ifup-routes ifup-tunnel network-functions-ipv6
ifcfg-lo ifdown-ib ifdown-post ifdown-Team ifup-aliases ifup-ippp ifup-plusb ifup-sit ifup-wireless
ifdown ifdown-ippp ifdown-ppp ifdown-TeamPort ifup-bnep ifup-ipv6 ifup-post ifup-Team init.ipv6-global
ifdown-bnep ifdown-ipv6 ifdown-routes ifdown-tunnel ifup-eth ifup-isdn ifup-ppp ifup-TeamPort network-functions

[root@lizhipeng01 network-scripts]# cp ifcfg-eno16777736 ifcfg-eno16777736:0

[root@lizhipeng01 ~]# ifdown eno16777736 && ifup eno16777736
Device 'eno16777736' successfully disconnected.
成功激活的连接（D-Bus 激活路径：/org/freedesktop/NetworkManager/ActiveConnection/2）
[root@lizhipeng01 ~]# ifconfig
eno16777736: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.5.128 netmask 255.255.255.0 broadcast 192.168.5.255
inet6 fe80::20c:29ff:fe7e:1a2f prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:7e:1a:2f txqueuelen 1000 (Ethernet)
RX packets 456 bytes 45573 (44.5 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 331 bytes 44706 (43.6 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

eno16777736:0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.5.150 netmask 255.255.255.0 broadcast 192.168.5.255 多了一个
ether 00:0c:29:7e:1a:2f txqueuelen 1000 (Ethernet)

[root@lizhipeng01 ~]# mii-tool eno16777736
eno16777736: negotiated 1000baseT-FD flow-control, link ok 连接了网线

[root@lizhipeng01 ~]# hostnamectl set-hostname lizhipenglinux01 更改主机名
[root@lizhipeng01 ~]# hostname
lizhipenglinux01
[root@lizhipeng01 ~]# bash 进入一个子进程
[root@lizhipenglinux01 ~]# exit
exit
[root@lizhipeng01 ~]# cat /etc/hostname
lizhipenglinux01

[root@lizhipeng01 ~]# cat /etc/resolv.conf
# Generated by NetworkManager
nameserver 119.29.29.29

[root@lizhipeng01 ~]# cat /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6

[root@lizhipeng01 ~]# vi /etc/hosts

127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.5.150 www.qq123.com

[root@lizhipeng01 ~]# ping www.qq123.com
PING www.qq123.com (192.168.5.150) 56(84) bytes of data.
64 bytes from www.qq123.com (192.168.5.150): icmp_seq=1 ttl=64 time=0.041 ms
64 bytes from www.qq123.com (192.168.5.150): icmp_seq=2 ttl=64 time=0.073 ms
64 bytes from www.qq123.com (192.168.5.150): icmp_seq=3 ttl=64 time=0.041 ms
64 bytes from www.qq123.com (192.168.5.150): icmp_seq=4 ttl=64 time=0.078 ms

[root@lizhipeng01 ~]# systemctl stop firewalld 关闭firewalld服务
[root@lizhipeng01 ~]# systemctl disable firewalld 禁止firewalld服务开机启动

[root@lizhipeng01 ~]# yum install -y iptables-services 安装iptables-services，这样就可以使用之前版本的iptables

[root@lizhipeng01 ~]# systemctl enable iptables 让它开机启动
[root@lizhipeng01 ~]# systemctl start iptables 启动iptables服务
[root@lizhipeng01 ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
344 23716 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
19 1633 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain OUTPUT (policy ACCEPT 200 packets, 21776 bytes)
pkts bytes target prot opt in out source destination

netfilter的5个表

filter表主要用于过滤包，是系统预设的表。该表内建3个链：INPUT、OUTPUT和FORWARD。input链作用于进入本机的包，output链作用于本机送出的包，forward链作用于那些跟本机无关的包。

nat表主要用于网络地址的转换，它也有3个链。prerouting链的作用是在包刚刚到达防火墙时改变它的目的地址，output链的作用是改变本地产生的包的目的地址，postrouting链的作用是在包即将离开防火墙时改变其源地址

mangle表主要用于给数据包做标记。

raw表可以实现不追踪某些数据包，默认系统的数据包都会被追踪，但追踪势必消耗一定的资源，所以可以用raw表来指定某些端口的包不被追踪。

security 表在centos6中是没有的，它用于强制访问控制（MAC）的网络规则。

netfilter的5个链

5个链分别为PREROUTING,INPUT,FORWARD,OUTPUT,POSTROUTING。

PREROUTING：数据包进入路由表之前。

INPUT：通过路由表后目的地本机。

FORWARDING：通过路由表后，目的地不为本机

OUTPUT：由本机产生，向外转发。

POSTROUTING：发送到网卡接口之前

iptables基本语法

（1）查看规则以及清楚规则

[root@lizhipenglinux01 ~]# iptables -nvL 默认的规则
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
146 13775 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
1 52 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
166 14005 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain OUTPUT (policy ACCEPT 121 packets, 10677 bytes)
pkts bytes target prot opt in out source destination

[root@lizhipenglinux01 ~]# service iptables restart 重启服务
Redirecting to /bin/systemctl restart iptables.service

[root@lizhipenglinux01 ~]# cat /etc/sysconfig/iptables 规则保存在该路径下
# sample configuration for iptables service
# you can edit this manually or use system-config-firewall
# please do not ask us to add additional ports/services to this default configuration
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT

[root@lizhipenglinux01 ~]# iptables -F 清空规则
[root@lizhipenglinux01 ~]# iptables -nvL 查看，没有了，但是实际文件里面还有，如下 cat /etc/sysconfig/iptables
Chain INPUT (policy ACCEPT 40 packets, 2640 bytes)
pkts bytes target prot opt in out source destination

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination

Chain OUTPUT (policy ACCEPT 21 packets, 2044 bytes)
pkts bytes target prot opt in out source destination

[root@lizhipenglinux01 ~]# cat /etc/sysconfig/iptables
# sample configuration for iptables service
# you can edit this manually or use system-config-firewall
# please do not ask us to add additional ports/services to this default configuration
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p icmp -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp -m state --state NEW -m tcp --dport 22 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT

[root@lizhipenglinux01 ~]# service iptables restart 重启服务
Redirecting to /bin/systemctl restart iptables.service 配置文件里面的规则会重新加载
[root@lizhipenglinux01 ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
28 1848 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain OUTPUT (policy ACCEPT 15 packets, 1444 bytes)
pkts bytes target prot opt in out source destination

[root@lizhipenglinux01 ~]# iptables -t filter -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
81 5476 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain OUTPUT (policy ACCEPT 47 packets, 5244 bytes)
pkts bytes target prot opt in out source destination

[root@lizhipenglinux01 ~]# iptables -Z; iptables -nvL -Z，清空数据pkts byte
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination

(2)增加/删除一条规则，其用法如下：

iptables -A INPUT -s 192.168.188.1 -p tcp --sport 1234 -d 192.168.188.128 --dport 80 -j DROP

没有加-t选项，所有针对的是filter表。这条规则中各个选项的作用如下。

-A/-D：表示增加/删除一条规则。

-I：表示插入一条规则，其实效果跟-A一样。

-p:表示指定协议，可以是tcp、udp或icmp。

--dport：跟-p一起使用，表示指定目标端口。

--sport：跟-p一起使用，表示指定源端口。

-s：表示指定源IP（可以是一个IP段）

-d：表示指定目的IP（可以是一个IP段）

-j：后面跟动作，其中ACCEPT表示允许包，DROP表示丢掉包，REJECT表示拒绝包。

-i：表示指定网卡

[root@lizhipenglinux01 ~]# iptables -A INPUT -s 192.168.5.1 -p tcp --sport 1234 -d 192.168.5.128 --dport 80 -j DROP
[root@lizhipenglinux01 ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
147 12832 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
7 697 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
0 0 DROP tcp -- * * 192.168.5.1 192.168.5.128 tcp spt:1234 dpt:80

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain OUTPUT (policy ACCEPT 15 packets, 1444 bytes)
pkts bytes target prot opt in out source destination

[root@lizhipenglinux01 ~]# iptables -I INPUT -p tcp --dport 80 -j DROP
[root@lizhipenglinux01 ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 DROP tcp -- * * 0.0.0.0/0 0.0.0.0/0 tcp dpt:80 -I 排在前面，类似于插队，优先过滤
286 22188 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
7 697 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
0 0 DROP tcp -- * * 192.168.5.1 192.168.5.128 tcp spt:1234 dpt:80 -A 排在后面

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain OUTPUT (policy ACCEPT 20 packets, 1936 bytes)
pkts bytes target prot opt in out source destination

[root@lizhipenglinux01 ~]# iptables -D INPUT -p tcp --dport 80 -j DROP -D：删除
[root@lizhipenglinux01 ~]# iptables -nvL 第一条没有了
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
345 27516 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
8 926 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
0 0 DROP tcp -- * * 192.168.5.1 192.168.5.128 tcp spt:1234 dpt:80

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain OUTPUT (policy ACCEPT 4 packets, 528 bytes)
pkts bytes target prot opt in out source destination

[root@lizhipenglinux01 ~]# iptables -D INPUT -s 192.168.5.1 -p tcp --sport 1234 -d 192.168.5.128 --dport 80 -j DROP
[root@lizhipenglinux01 ~]# iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
452 37888 ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
0 0 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
8 926 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited

Chain OUTPUT (policy ACCEPT 4 packets, 656 bytes)
pkts bytes target prot opt in out source destination

有时候服务器上的iptables过多，想删除一条规则，但是又不容易掌握创建时的规则。有一种比较简单的方法，先查看iptables。

-----------------------

[root@lizhipenglinux01 ~]# iptables -t nat -nvL
Chain PREROUTING (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination

Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination

Chain POSTROUTING (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination

-t选项后面跟表名，-nvL表示查看该表的规则，其中-n表示不针对IP反解析主机名，-L表示列出，-v表示列出的信息更加详细。如果不加-t选项，则打印filter表的相关信息

清除规则的命令中，用的最多的就是下面2个

iptables -F

iptables -Z

-F表示把所有规则全部删除，如果不加-t指定表，默认只清除filter表的规则。-Z表示把包以及流量计数器置零。