ubuntu 双网卡默认路由问题

深碍√TFBOYSˉ_ 2023-07-09 02:29 1阅读 0赞

#### 问题描述 ####

Linux系统有两块网卡,一块A(enp0s3,NAT,DHCP自动获取)负责对外请求,一块B(enp0s8,静态IP,内网)负责对内.当只有A的时候,可以正常上网,但加入B以后,则无法上网.

enp0s3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 1.1.1.8  netmask 255.255.255.0  broadcast 1.1.1.255
            inet6 fe80::a00:27ff:fe58:72e6  prefixlen 64  scopeid 0x20<link>
            ether 08:00:27:58:72:e6  txqueuelen 1000  (Ethernet)
            RX packets 741  bytes 57262 (57.2 KB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 636  bytes 88242 (88.2 KB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
    
    enp0s8: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
            inet 10.0.3.15  netmask 255.255.255.0  broadcast 10.0.3.255
            inet6 fe80::a00:27ff:fe5c:c020  prefixlen 64  scopeid 0x20<link>
            ether 08:00:27:5c:c0:20  txqueuelen 1000  (Ethernet)
            RX packets 642  bytes 600938 (600.9 KB)
            RX errors 0  dropped 0  overruns 0  frame 0
            TX packets 368  bytes 27118 (27.1 KB)
            TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

#### 问题解决 ####

使用route命令,发现系统多添加了一条默认路由

Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    default         1.1.1.1         0.0.0.0         UG    0      0        0 enp0s3
    default         10.0.3.2        0.0.0.0         UG    100    0        0 enp0s8
    1.1.1.0         0.0.0.0         255.255.255.0   U     0      0        0 enp0s3
    10.0.3.0        0.0.0.0         255.255.255.0   U     0      0        0 enp0s8
    10.0.3.2        0.0.0.0         255.255.255.255 UH    100    0        0 enp0s8

第一条就是多添加的路由,而且他的优先级是0,比我需要的第二条的优先级100,要高

经过查资料发现,需要把网卡A enp0s8对应的网卡,设置Gateway,我一查,果然没有

所以修改配置文件  
如下,10.0.3.2是根据route命令查询得来的

# This file is generated from information provided by
    # the datasource. Changes to it will not persist across an instance.
    # To disable cloud-init's network configuration capabilities, write a file
    # /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg with the following:
    # network: {config: disabled}
    network:
        ethernets:
            enp0s8:
              dhcp4: true
              gateway4: 10.0.3.2
            enp0s3:
                addresses:
                - 1.1.1.8/24
                gateway4: 1.1.1.1
                nameservers: { }
        version: 2

保存,执行 netplan apply

再次执行,route命令,显示如下,问题解决

Kernel IP routing table
    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    default         one.one.one.one 0.0.0.0         UG    0      0        0 enp0s3
    default         _gateway        0.0.0.0         UG    0      0        0 enp0s8
    default         _gateway        0.0.0.0         UG    100    0        0 enp0s8
    1.1.1.0         0.0.0.0         255.255.255.0   U     0      0        0 enp0s3
    10.0.3.0        0.0.0.0         255.255.255.0   U     0      0        0 enp0s8
    _gateway        0.0.0.0         255.255.255.255 UH    100    0        0 enp0s8