BCLinux系统路由冲突无法访问外网的解决方法

腾讯云知识 10月 22, 2020 102 0

影响版本

   BigCloud Enterprise Linux 6.5 64bit

   BigCloud Enterprise Linux 7.1 64bit

解决方案：

   BCLinux6 默认未安装NetworkManager，使用DHCP方式，可以在if-eth*配置文件中添加METRIC=xx参数（注意：每个if-eth配置文件均需添加此参数），并重启网络即可生效，默认值越小，路由选择越优先，用户预期想使用的那个路由的METRIC值必须是最小的。

   BCLinux7 安装NetworkManager，使用DHCP方式，可以在if-eth*配置文件中添加IPV4_ROUTE_METRIC=xx参数（注意：每个if-eth配置文件均需添加此参数），并重启网络即可生效，默认值越小，路由选择越优先，用户预期想使用的那个路由的IPV4_ROUTE_METRIC值必须是最小的。

问题分析：

1. BigCloud Enterprise Linux 6.5 64bit

默认未安装NetworkManager

默认采用DHCP方式获取网卡信息

创建时默认一个网卡：

名称 port163709

编码 5ea1ee92-c7ac-42f8-9e99-b84dac032c26

关联腾讯云服务器   TestNetRoute

IP地址    10.112.137.225

公网IP    112.35.30.85

进入腾讯云服务器：

[root@testnetroute ~]# ip a s

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 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

    inet6 ::1/128 scope host

       valid_lft forever preferred_lft forever

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether fa:16:3e:87:44:46 brd ff:ff:ff:ff:ff:ff

    inet 10.112.137.225/22 brd 10.112.139.255 scope global eth0

    inet6 fe80::f816:3eff:fe87:4446/64 scope link

       valid_lft forever preferred_lft forever

[root@testnetroute ~]# ip route show

10.112.136.0/22 dev eth0 proto kernel scope link src 10.112.137.225

169.254.0.0/16 dev eth0 scope link metric 1002

default via 10.112.136.1 dev eth0

此种情况下，用户通过云平台上提供的接口，新增了一个网卡，

名称 wyytest01

编码 4087a96b-6d38-4253-a2a9-f32c6fd64ce5

关联腾讯云服务器   TestNetRoute

IP地址    192.168.138.4

公网IP

进入腾讯云服务器，查看其信息：

[root@testnetroute ~]# ip a s

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 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

    inet6 ::1/128 scope host

       valid_lft forever preferred_lft forever

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether fa:16:3e:87:44:46 brd ff:ff:ff:ff:ff:ff

    inet 10.112.137.225/22 brd 10.112.139.255 scope global eth0

    inet6 fe80::f816:3eff:fe87:4446/64 scope link

       valid_lft forever preferred_lft forever

3: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000

    link/ether fa:16:3e:6f:67:6b brd ff:ff:ff:ff:ff:ff

[root@testnetroute ~]# ip route show

10.112.136.0/22 dev eth0 proto kernel scope link src 10.112.137.225

169.254.0.0/16 dev eth0 scope link metric 1002

default via 10.112.136.1 dev eth0

由于el6系统中无NetworkManager，因此可以看到，eth1没有获取到ip，手动配置网络文件：

[root@testnetroute ~]# cd /etc/sysconfig/network-scripts/

[root@testnetroute /etc/sysconfig/network-scripts]# cp ifcfg-eth0 ifcfg-eth1

[root@testnetroute /etc/sysconfig/network-scripts]# vi ifcfg-eth1 #修改文件如下

DEVICE=eth1

TYPE=Ethernet

ONBOOT=yes

BOOTPROTO=dhcp

重启网络：

[root@testnetroute ~]# ifup eth1

发现默认路由变为了：

[root@testnetroute ~]# ip route show

192.168.138.0/24 dev eth1 proto kernel scope link src 192.168.138.4

10.112.136.0/22 dev eth0 proto kernel scope link src 10.112.137.225

169.254.0.0/16 dev eth0 scope link metric 1002

169.254.0.0/16 dev eth1 scope link metric 1003

default via 192.168.138.1 dev eth1

此时，为了使默认路由仍走10.112.136.1，可为2个网卡分别配置METRIC参数，配置如下：

[root@testnetroute /etc/sysconfig/network-scripts]# cat ifcfg-eth0

DEVICE=eth0

TYPE=Ethernet

ONBOOT=yes

BOOTPROTO=dhcp

METRIC=10       #增加此行如左

[root@testnetroute /etc/sysconfig/network-scripts]# cat ifcfg-eth1

DEVICE=eth1

TYPE=Ethernet

ONBOOT=yes

BOOTPROTO=dhcp

METRIC=20       #增加此行如左

重启网络：

[root@testnetroute ~]# service network restart

重新查看路由：

[root@testnetroute ~]# ip route show

192.168.138.0/24 dev eth1 proto kernel scope link src 192.168.138.4

10.112.136.0/22 dev eth0 proto kernel scope link src 10.112.137.225

169.254.0.0/16 dev eth0 scope link metric 1002

169.254.0.0/16 dev eth1 scope link metric 1003

default via 10.112.136.1 dev eth0 metric 10

default via 192.168.138.1 dev eth1 metric 20

测试访问8.8.8.8所走的默认路由：

[root@testnetroute ~]# ip route get 8.8.8.8

8.8.8.8 via 10.112.136.1 dev eth0 src 10.112.137.225

    cache mtu 1500 advmss 1460 hoplimit 64

更改默认路由成功。

2. BigCloud Enterprise Linux 7.1 64bit

默认安装NetworkManager

默认采用DHCP方式获取网卡信息

创建时默认一个网卡：

名称 port499273

编码 70ed40b5-ba0c-4dcd-88e5-c10df1efb371

关联腾讯云服务器   TestNetRoute7

IP地址    10.112.137.226

公网IP    112.35.30.90

进入腾讯云服务器：

[root@testnetroute7 ~]# ip a s

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: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether fa:16:3e:8d:8e:61 brd ff:ff:ff:ff:ff:ff

    inet 10.112.137.226/22 brd 10.112.139.255 scope global eth0

       valid_lft forever preferred_lft forever

    inet6 fe80::f816:3eff:fe8d:8e61/64 scope link

       valid_lft forever preferred_lft forever

[root@testnetroute7 ~]# ip route show

default via 10.112.136.1 dev eth0 proto static metric 100

10.112.136.0/22 dev eth0 proto kernel scope link src 10.112.137.226 metric 100

此种情况下，用户通过云平台上提供的接口，新增了一个网卡，

名称 wyytest02

编码 90bdcbc2-2729-486f-a58b-e3601db27f61

关联腾讯云服务器   TestNetRoute7

IP地址    192.168.137.4

公网IP

进入腾讯云服务器，查看网络信息（由于el7系统中默认安装了NetworkManager，因此eth1自动获取到ip：192.168.137.4）：

[root@testnetroute7 ~]# ip a s

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: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether fa:16:3e:8d:8e:61 brd ff:ff:ff:ff:ff:ff

    inet 10.112.137.226/22 brd 10.112.139.255 scope global eth0

       valid_lft forever preferred_lft forever

    inet6 fe80::f816:3eff:fe8d:8e61/64 scope link

       valid_lft forever preferred_lft forever

3: eth1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000

    link/ether fa:16:3e:dd:4a:8e brd ff:ff:ff:ff:ff:ff

  inet 192.168.137.4/24 brd 192.168.137.255 scope global eth1

       valid_lft forever preferred_lft forever

    inet6 fe80::f816:3eff:fedd:4a8e/64 scope link

       valid_lft forever preferred_lft forever

查看路由状态：

[root@testnetroute7 ~]# ip route show

default via 10.112.136.1 dev eth0 proto static metric 100

default via 192.168.137.1 dev eth1 proto static metric 101

10.112.136.0/22 dev eth0 proto kernel scope link src 10.112.137.226 metric 100

192.168.137.0/24 dev eth1 proto kernel scope link src 192.168.137.4 metric 100

测试系统访问8.8.8.8所走默认路由：

[root@testnetroute7 ~]# ip route get 8.8.8.8

8.8.8.8 via 10.112.136.1 dev eth0 src 10.112.137.226

    cache

若当前路由并不是想要的，则用户可以自行更改（假设想使用192.168.137.1）：

[root@testnetroute7 /etc/sysconfig/network-scripts]# cat ifcfg-eth0

NAME=eth0

TYPE=Ethernet

BOOTPROTO=dhcp

DEVICE=eth0

ONBOOT=yes

IPV4_ROUTE_METRIC=20    #添加内容如左

[root@testnetroute7 /etc/sysconfig/network-scripts]# cat ifcfg-eth1

NAME=eth1

TYPE=Ethernet

BOOTPROTO=dhcp

DEVICE=eth1

ONBOOT=yes

IPV4_ROUTE_METRIC=10    #添加内容如左

重启服务：

[root@testnetroute7 ~]# systemctl restart network

查看路由状态：

[root@testnetroute7 ~]# ip route show

default via 192.168.137.1 dev eth1 proto static metric 10

default via 10.112.136.1 dev eth0 proto static metric 20

10.112.136.0/22 dev eth0 proto kernel scope link src 10.112.137.226 metric 20

192.168.137.0/24 dev eth1 proto kernel scope link src 192.168.137.4 metric 10

测试系统访问8.8.8.8所走默认路由：

[root@testnetroute7 ~]# ip route get 8.8.8.8

8.8.8.8 via 192.168.137.1 dev eth0 src 192.168.137.4

    cache

更改默认路由成功。