桥接就是把一台机器上的若干个网络接口连接起来，其结果是，其中一个网卡 收到的报文会被复制给其他网卡发送出去。以使得网口之间的报文能够互相转 发。

1.创建一个桥接设备和会话

[root@localhost ~]# nmcli c add type bridge con-name br1 ifname br1
 ipv4.addresses 192.168.179.122/24 
ipv4.gateway 192.168.179.2 
ipv4.dns 114.114.114.114 ipv4.method manual 

2.添加会话到桥接设备

[root@localhost ~]# nmcli c add type bridge-slave con-name br1-port1 
ifname ens160 master br1
[root@localhost ~]# nmcli c add type bridge-slave con-name br1-port2 
ifname ens224 master br1

3.启用设备，先启用slave，然后启用master（bridge）

[root@localhost ~]# nmcli c up br1-port1
[root@localhost ~]# nmcli c up br1-port2
[root@localhost ~]# nmcli c up br1

4.查看网络连接状态

[root@localhost ~]# nmcli c show
NAME       UUID                                  TYPE      DEVICE 
br1        732e51d5-6ec4-4a27-acdd-a723d68d7ec3  bridge    br1    
br1-port1  2d300655-a746-4636-bd8d-bfe6b45bdce5  ethernet  ens160 
br1-port2  5e3819dc-7ce5-4dfa-83f4-d892a76680bc  ethernet  ens224 
ens160     d28cfa05-03c6-449b-975b-6fe3f4672cd6  ethernet  --     
rhce       74e098f7-4c7d-4401-93f2-4b156cfce63d  ethernet  --     

[root@localhost ~]# ifconfig
br1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.179.122  netmask 255.255.255.0  broadcast 192.168.179.255
        inet6 fe80::e6e8:a065:11e9:8942  prefixlen 64  scopeid 0x20<link>
        ether 00:0c:29:bd:80:47  txqueuelen 1000  (Ethernet)
        RX packets 170  bytes 36007 (35.1 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 71  bytes 7898 (7.7 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

ens160: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        ether 00:0c:29:bd:80:47  txqueuelen 1000  (Ethernet)
        RX packets 2281  bytes 294532 (287.6 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 434  bytes 50857 (49.6 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

ens224: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        ether 00:0c:29:bd:80:51  txqueuelen 1000  (Ethernet)
        RX packets 1109  bytes 120856 (118.0 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 5  bytes 240 (240.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

可以看到br1上是我们配置的ip

5.抓包验证

(1)使用windows端ping192.168.179.122，在ens160上抓包

来自 192.168.179.122 的回复: 字节=32 时间<1ms TTL=64
来自 192.168.179.122 的回复: 字节=32 时间<1ms TTL=64
来自 192.168.179.122 的回复: 字节=32 时间<1ms TTL=64
来自 192.168.179.122 的回复: 字节=32 时间<1ms TTL=64
来自 192.168.179.122 的回复: 字节=32 时间<1ms TTL=64
来自 192.168.179.122 的回复: 字节=32 时间<1ms TTL=64
来自 192.168.179.122 的回复: 字节=32 时间<1ms TTL=64
来自 192.168.179.122 的回复: 字节=32 时间<1ms TTL=64

[root@localhost ~]# tcpdump icmp -i ens160
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on ens160, link-type EN10MB (Ethernet), capture size 262144 bytes
00:55:07.723624 IP 192.168.179.1 > localhost.localdomain: ICMP echo request, id 1, seq 24, length 40
00:55:07.723658 IP localhost.localdomain > 192.168.179.1: ICMP echo reply, id 1, seq 24, length 40
00:55:08.728605 IP 192.168.179.1 > localhost.localdomain: ICMP echo request, id 1, seq 25, length 40
00:55:08.728641 IP localhost.localdomain > 192.168.179.1: ICMP echo reply, id 1, seq 25, length 40
00:55:09.733592 IP 192.168.179.1 > localhost.localdomain: ICMP echo request, id 1, seq 26, length 40
00:55:09.733626 IP localhost.localdomain > 192.168.179.1: ICMP echo reply, id 1, seq 26, length 40
00:55:10.739531 IP 192.168.179.1 > localhost.localdomain: ICMP echo request, id 1, seq 27, length 40

在ens224上抓包

[root@localhost ~]# tcpdump icmp -i ens224
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on ens224, link-type EN10MB (Ethernet), capture size 262144 bytes
01:22:13.280200 IP 192.168.179.1 > bogon: ICMP echo request, id 1, seq 982, length 40
01:22:13.281985 IP bogon > 192.168.179.1: ICMP echo reply, id 1, seq 982, length 40
01:22:14.298299 IP 192.168.179.1 > bogon: ICMP echo request, id 1, seq 983, length 40
01:22:14.298310 IP bogon > 192.168.179.1: ICMP echo reply, id 1, seq 983, length 40
01:22:15.317315 IP 192.168.179.1 > bogon: ICMP echo request, id 1, seq 984, length 40
01:22:15.317671 IP bogon > 192.168.179.1: ICMP echo reply, id 1, seq 984, length 40
01:22:16.328481 IP 192.168.179.1 > bogon: ICMP echo request, id 1, seq 985, length 40
01:22:16.328884 IP bogon > 192.168.179.1: ICMP echo reply, id 1, seq 985, length 40
01:22:17.336825 IP 192.168.179.1 > bogon: ICMP echo request, id 1, seq 986, length 40
01:22:17.337111 IP bogon > 192.168.179.1: ICMP echo reply, id 1, seq 986, length 40
01:22:18.350702 IP 192.168.179.1 > bogon: ICMP echo request, id 1, seq 987, length 40

成功抓包