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添加到linux网桥后主机无法访问

tag-icon • tag-icon linux networking bridge
添加到linux网桥后主机无法访问

我正在学习Linux Bridge的基础知识，并且做了一个实验。

我的网络信息是这样的：

:)[00:32][root@openstack]~ # ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
    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: enp0s8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1430 qdisc pfifo_fast state UP qlen 1000
    link/ether 08:00:27:df:9e:b2 brd ff:ff:ff:ff:ff:ff
    inet 10.140.28.35/24 brd 10.140.28.255 scope global dynamic enp0s8
       valid_lft 80937sec preferred_lft 80937sec
    inet6 2001:420:588c:1305:3c74:1500:63cd:fb4b/128 scope global dynamic
       valid_lft 1203623sec preferred_lft 598823sec
    inet6 fe80::a00:27ff:fedf:9eb2/64 scope link
       valid_lft forever preferred_lft forever

我可以从外部 ping 通 10.140.28.35。然后我创建了一座桥：

:)[00:33][root@openstack]~ # brctl addbr br0; ip l set dev br0 up
:)[00:34][root@openstack]~ # ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
    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: enp0s8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1430 qdisc pfifo_fast state UP qlen 1000
    link/ether 08:00:27:df:9e:b2 brd ff:ff:ff:ff:ff:ff
    inet 10.140.28.35/24 brd 10.140.28.255 scope global dynamic enp0s8
       valid_lft 80854sec preferred_lft 80854sec
    inet6 2001:420:588c:1305:3c74:1500:63cd:fb4b/128 scope global dynamic
       valid_lft 1203540sec preferred_lft 598740sec
    inet6 fe80::a00:27ff:fedf:9eb2/64 scope link
       valid_lft forever preferred_lft forever
3: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN
    link/ether b2:25:c0:ee:ad:d0 brd ff:ff:ff:ff:ff:ff

然后我将接口 enp0s8 添加到桥中：

:)[00:34][root@openstack]~ # brctl addif br0 enp0s8
:)[00:39][root@openstack]~ # brctl show
bridge name     bridge id               STP enabled     interfaces
br0             8000.080027df9eb2       no              enp0s8

此时，我无法再从外部 ping 通 10.140.28.35。

我不明白为什么会发生这种情况。当我为网桥设置相同的IP地址后，它又变得可以访问了。

ip a add 10.140.28.35/24 dev br0

我注意到 br0 的 MAC 与 enp0s8 相同：

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
    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: enp0s8: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1430 qdisc pfifo_fast master br0 state UP qlen 1000
    link/ether 08:00:27:df:9e:b2 brd ff:ff:ff:ff:ff:ff
    inet 10.140.28.35/24 brd 10.140.28.255 scope global dynamic enp0s8
       valid_lft 80515sec preferred_lft 80515sec
    inet6 2001:420:588c:1305:3c74:1500:63cd:fb4b/128 scope global dynamic
       valid_lft 1203201sec preferred_lft 598401sec
    inet6 fe80::a00:27ff:fedf:9eb2/64 scope link
       valid_lft forever preferred_lft forever
3: br0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1430 qdisc noqueue state UP
    link/ether 08:00:27:df:9e:b2 brd ff:ff:ff:ff:ff:ff
    inet 10.140.28.35/24 scope global br0
       valid_lft forever preferred_lft forever
    inet6 fe80::a00:27ff:fedf:9eb2/64 scope link
       valid_lft forever preferred_lft forever

为什么一开始无法访问，为什么我必须将相同的IP地址设置为br0？

答案1

桥是第 2 层抽象，您不能在连接到它的接口上进行第 3 层寻址，实际上 enp0s8 和 br0 是相同的东西。尝试去掉enp0s8上的IP，并为br0设置一个IP。

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