CentOS7 Firewall NAT 及端口映射

本节介绍用CentOS7的Firewalll来做NAT以及端口映射

实验拓扑:

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因为我的环境里CentOS7上有KVM虚拟机需要共享网卡上网，所以我把网卡都添加到了桥里面，当然这里也可以不用桥，直接用物理网口；

用nmcli创建桥，并添加网口到桥；然后给桥设置IP地址：

先创建两个桥"br-ex"和"br-in"

[root@localhost ~]# nmcli con add type bridge con-name br-ex ifname br-ex autoconnect yes

Connection 'br-ex' (2b823432-af25-497a-9b59-8b63709ef8ad) successfully added.

[root@localhost ~]# nmcli con add type bridge con-name br-in ifname br-in autoconnect yes

Connection 'br-in' (e9c07ace-4182-41db-8208-7b93c139842f) successfully added.

[root@localhost ~]# nmcli con show

NAME                UUID                                  TYPE            DEVICE      

Wired connection 1  8c368bb5-8050-355f-a513-49b5c4bca3f8  802-3-ethernet  ens36       

br-ex               2b823432-af25-497a-9b59-8b63709ef8ad  bridge          br-ex       

br-in e9c07ace-4182-41db-8208-7b93c139842f  bridge          br-in

eno16777736         01ef745d-f2ee-421a-8dd5-4da36d509e2a  802-3-ethernet  eno16777736 

[root@localhost ~]#
将网卡"ens36"加入到"br-in",将网卡"eno16777736"加入到"br-ex"

这里首先删除nmcli里的connection

[root@localhost ~]# nmcli connection delete eno16777736 

Connection 'eno16777736' (01ef745d-f2ee-421a-8dd5-4da36d509e2a) successfully deleted.

[root@localhost ~]# nmcli con delete "Wired connection 1" 

Connection 'Wired connection 1' (8c368bb5-8050-355f-a513-49b5c4bca3f8) successfully deleted.

[root@localhost ~]#
然后将网卡添加到相应的桥中

[root@localhost ~]# nmcli connection add type bridge-slave con-name eno16777736 ifname eno16777736 autoconnect yes master br-ex

Connection 'eno16777736' (cc6b32bf-4a23-42a1-af6e-85cf93f1686f) successfully added.

[root@localhost ~]# nmcli connection add type bridge-slave con-name ens36 ifname ens36 autoconnect yes master br-in

Connection 'ens36' (2b7cf193-22eb-4b61-8887-1aed25b33fd1) successfully added.

[root@localhost ~]# nmcli con show

NAME         UUID                                  TYPE            DEVICE      

br-ex        2b823432-af25-497a-9b59-8b63709ef8ad  bridge          br-ex       

br-in e9c07ace-4182-41db-8208-7b93c139842f  bridge          br-in

eno16777736  cc6b32bf-4a23-42a1-af6e-85cf93f1686f  802-3-ethernet  eno16777736 

ens36        2b7cf193-22eb-4b61-8887-1aed25b33fd1  802-3-ethernet  ens36       

[root@localhost ~]#
此环境中外网的IP是自动获取的，当然用固定的也是可以的

下面要设置NAT了

1、启用IP转发

[root@localhost ~]# echo "net.ipv4.ip_forward = 1" >> /etc/sysctl.conf

[root@localhost ~]# sysctl -p    #使更改立即生效

net.ipv4.ip_forward = 1

[root@localhost ~]#
2、在Firewall中将桥放到相应的zone

[root@localhost ~]# firewall-cmd --zone=external --change-interface=br-ex --permanent 

The interface is under control of NetworkManager, setting zone to 'external'.

success

[root@localhost ~]# firewall-cmd --zone=internal --change-interface=br-in --permanent 

The interface is under control of NetworkManager, setting zone to 'internal'.

success

[root@localhost ~]#firewall-cmd --list-all-zones

...省略...

internal (active)

target: default

icmp-block-inversion: no

interfaces: br-in

sources: 

services: dhcpv6-client mdns samba-client ssh

ports: 

protocols: 

masquerade: no

forward-ports: 

sourceports: 

icmp-blocks: 

rich rules: 


external (active)

target: default

icmp-block-inversion: no

interfaces: br-ex

sources: 

services: ssh

ports: 

protocols: 

masquerade: yes

forward-ports: 

sourceports: 

icmp-blocks: 

rich rules: 

...省略...

3、设置IP地址伪装（让所有内网的流量出去到外网源地址都伪装成br-ex的地址）

[root@localhost ~]# firewall-cmd --zone=external --add-masquerade --permanent 

Warning: ALREADY_ENABLED: masquerade

success

[root@localhost ~]# firewall-cmd --zone=external --list-all

external (active)

target: default

icmp-block-inversion: no

interfaces: br-ex

sources: 

services: ssh

ports: 

protocols: 

masquerade: yes

forward-ports: 

sourceports: 

icmp-blocks: 

rich rules: 


[root@localhost ~]# firewall-cmd --zone=internal --list-all

internal (active)

target: default

icmp-block-inversion: no

interfaces: br-in

sources: 

services: dhcpv6-client mdns samba-client ssh

ports: 

protocols: 

masquerade: no

forward-ports: 

sourceports: 

icmp-blocks: 

rich rules:

4、设置NAT

[root@localhost ~]# firewall-cmd --permanent --direct --passthrough ipv4 -t nat -I POSTROUTING -o br-ex -j MASQUERADE -s 10.1.1.0/24

success

[root@localhost ~]# firewall-cmd --reload    #reload Firewall让配置生效

success

5、给"br-in"设置IP地址

[root@localhost ~]# nmcli con modify br-in ipv4.addresses 10.1.1.254/24 autoconnect yes ipv4.method manual

[root@localhost ~]# nmcli con up br-in

Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/50)

[root@localhost ~]# ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1

link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

inet 127.0.0.1/8 scope host lo

valid_lft forever preferred_lft forever

inet6 ::1/128 scope host 

valid_lft forever preferred_lft forever

2: eno16777736: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br-ex state UP qlen 1000

link/ether 00:0c:29:07:82:16 brd ff:ff:ff:ff:ff:ff

3: ens36: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br-in state UP qlen 1000

link/ether 00:0c:29:07:82:20 brd ff:ff:ff:ff:ff:ff

4: br-ex: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP qlen 1000

link/ether 00:0c:29:07:82:16 brd ff:ff:ff:ff:ff:ff

inet 192.168.127.129/24 brd 192.168.127.255 scope global dynamic br-ex

valid_lft 1512sec preferred_lft 1512sec

inet6 fe80::2ab1:e7db:9af:27f/64 scope link 

valid_lft forever preferred_lft forever

19: br-in: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc noqueue state DOWN qlen 1000

link/ether 00:0c:29:07:82:20 brd ff:ff:ff:ff:ff:ff

inet 10.1.1.254/24 brd 10.1.1.255 scope global br-in

valid_lft forever preferred_lft forever

[root@localhost ~]#

#这个时候br-in还没有完全UP起来，稍等几秒钟再看

[root@localhost ~]# ip a

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN qlen 1

link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

inet 127.0.0.1/8 scope host lo

valid_lft forever preferred_lft forever

inet6 ::1/128 scope host 

valid_lft forever preferred_lft forever

2: eno16777736: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br-ex state UP qlen 1000

link/ether 00:0c:29:07:82:16 brd ff:ff:ff:ff:ff:ff

3: ens36: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast master br-in state UP qlen 1000

link/ether 00:0c:29:07:82:20 brd ff:ff:ff:ff:ff:ff

4: br-ex: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP qlen 1000

link/ether 00:0c:29:07:82:16 brd ff:ff:ff:ff:ff:ff

inet 192.168.127.129/24 brd 192.168.127.255 scope global dynamic br-ex

valid_lft 1435sec preferred_lft 1435sec

inet6 fe80::2ab1:e7db:9af:27f/64 scope link 

valid_lft forever preferred_lft forever

19: br-in: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP qlen 1000

link/ether 00:0c:29:07:82:20 brd ff:ff:ff:ff:ff:ff

inet 10.1.1.254/24 brd 10.1.1.255 scope global br-in

valid_lft forever preferred_lft forever

inet6 fe80::5bec:cd7f:9ae7:12a5/64 scope link 

valid_lft forever preferred_lft forever

#可以看到br-in已经UP起来了

6、到win7中测试

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这里因为没有在CentOS7里配置DHCP服务，所以win7需要手动配置IP

至此NAT设置完成

7、端口映射

这里从外网访问win7的远程桌面（TCP3389号端口）为例

再外网访问192.168.127.129的3389号端口，Firewall会将流量转给win7（10.1.1.2）

[root@localhost ~]# firewall-cmd --zone=external --add-forward-port=port=3389:proto=tcp:toport=3389:toaddr=10.1.1.2 --permanent 

success

[root@localhost ~]# firewall-cmd --reload 

success

[root@localhost ~]# firewall-cmd --zone=external --list-forward-ports 

port=3389:proto=tcp:toport=3389:toaddr=10.1.1.2

[root@localhost ~]#
配置win7的远程桌面后验证

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posted @ 2018-05-28 10:42  Hito  阅读(2309)  评论(0)  编辑  收藏  举报