网络管理¶

1 工具安装¶

# ifconfig
$ yum install -y net-tools
# ip、ss、tc
$ yum install -y iproute
# ping
$ yum install -y iputils

2 ip¶

功能：显示/操作路由、网络设备、接口和隧道
语法：

ip [ OPTIONS ] OBJECT { COMMAND | help }

OBJECT := { link | address | addrlabel | route | rule | neigh | ntable | tunnel | tuntap | maddress | mroute |
mrule | monitor | xfrm | netns | l2tp | tcp_metrics | token | macsec }

OPTIONS := { -V[ersion] | -h[uman-readable] | -s[tatistics] | -d[etails] | -r[esolve] | -iec | -f[amily] {
inet | inet6 | link } | -4 | -6 | -I | -D | -B | -0 | -l[oops] { maximum-addr-flush-attempts } |
-o[neline] | -rc[vbuf] [size] | -t[imestamp] | -ts[hort] | -n[etns] name | -N[umeric] | -a[ll] |
-c[olor] | -br[ief] | -j[son] | -p[retty] }

2.1 ip addr显示网卡信息¶

语法:
显示所有网卡信息：ip addr [show]
显示指定网卡信息：ip addr show [dev] 网卡名
示例

~$ ip addr show eth0
6: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:15:5d:37:d1:0f brd ff:ff:ff:ff:ff:ff
    inet 172.26.11.86/20 brd 172.26.15.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::215:5dff:fe37:d10f/64 scope link
       valid_lft forever preferred_lft forever

2.2 ip route 路由表管理¶

2.2.1 主机路由、网络路由、默认路由¶

主机路由就是x.x.x.x/32，意思是仅仅到x.x.x.x的报文听我的。
网络路由就是x.x.x.x/n,意思是到x.x.x.x/n的报文听我的。
默认路由是0.0.0.0/0，意思是实在没人要的报文听我的。

2.2.1.1 显示路由¶

语法：
ip route
ip route show
ip route list
示例

$ ip route
default via 172.26.0.1 dev eth0
172.26.0.0/20 dev eth0 proto kernel scope link src 172.26.3.81

2.2.2 添加路由¶

2.2.3 删除路由¶

语法：ip route del [ip/掩码|default]
示例1：删除指定路由

$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         172.26.0.1      0.0.0.0         UG    0      0        0 eth0
172.26.0.0      0.0.0.0         255.255.240.0   U     0      0        0 eth0
$ sudo ip route del 172.26.0.0/255.255.240.0
$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         172.26.0.1      0.0.0.0         UG    0      0        0 eth0

示例2：删除默认路由，ip+掩码

$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         172.26.0.1      0.0.0.0         UG    0      0        0 eth0
$ sudo ip route del 0.0.0.0/0.0.0.0
$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface

示例3：删除默认路由，default

$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         172.26.0.1      0.0.0.0         UG    0      0        0 eth0
$ sudo ip route del default
$ route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface

2.3 ip link 网络设备配置¶

2.3.1 启停网卡¶

语法：ip link set 网卡名 [down|up]
示例1：停止网卡

$ sudo ip link set eth0 down
$ ip addr show eth0
4: eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc mq state DOWN group default qlen 1000
    link/ether 00:15:5d:37:d4:16 brd ff:ff:ff:ff:ff:ff
    inet 172.26.3.81/20 brd 172.26.15.255 scope global eth0
       valid_lft forever preferred_lft forever

示例2：启动网卡，可能需要重新添加路由

$ sudo ip link set eth0 up
$ ip addr show eth0
4: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 00:15:5d:37:d4:16 brd ff:ff:ff:ff:ff:ff
    inet 172.26.3.81/20 brd 172.26.15.255 scope global eth0
       valid_lft forever preferred_lft forever
    inet6 fe80::215:5dff:fe37:d416/64 scope link
       valid_lft forever preferred_lft forever

3 route¶

参考资料

4 nslookup¶

4.1 域名解析¶

$ nslookup baidu.com
服务器:  public1.114dns.com
Address:  114.114.114.114

非权威应答:
名称:    baidu.com
Addresses:  220.181.38.251
          220.181.38.148