查看IP

ifconfig

em1       Link encap:Ethernet  HWaddr F0:1F:AF:D6:17:DD  
          inet addr:115.238.54.116  Bcast:115.238.54.127  Mask:255.255.255.224
          inet6 addr: fe80::f21f:afff:fed6:17dd/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:83248115 errors:0 dropped:0 overruns:0 frame:0
          TX packets:50674679 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:10627919322 (9.8 GiB)  TX bytes:13311903923 (12.3 GiB)
          Interrupt:16 
em1:0     Link encap:Ethernet  HWaddr F0:1F:AF:D6:17:DD  
          inet addr:121.52.229.126  Bcast:121.52.229.127  Mask:255.255.255.224
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:16 
em1:1     Link encap:Ethernet  HWaddr F0:1F:AF:D6:17:DD  
          inet addr:120.199.8.215  Bcast:120.199.8.223  Mask:255.255.255.240
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          Interrupt:16 
lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:2228411 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2228411 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:667383706 (636.4 MiB)  TX bytes:667383706 (636.4 MiB)

（em1表示网卡对应的三个IP；lo表示本地环回IP）

查看Gateway（官网）

netstat -rn 或 route -n
或
ip route show
或
traceroute

Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
120.199.8.208   0.0.0.0         255.255.255.240 U         0 0          0 em1
115.238.54.96   0.0.0.0         255.255.255.224 U         0 0          0 em1
121.52.229.96   0.0.0.0         255.255.255.224 U         0 0          0 em1
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 em1
0.0.0.0         115.238.54.97   0.0.0.0         UG        0 0          0 em1

（以0.0.0.0开始的行的Gateway是默认网关）

查看DNS

cat /etc/resolv.conf

nameserver 202.101.172.47
nameserver 221.12.1.227

设置IP（同时也可以根据这个反推IP相关信息）：

CentOS 6+：http://www.cnblogs.com/EasonJim/p/8072875.html

Ubuntu 16+：http://www.cnblogs.com/EasonJim/p/7857671.html

via.https://www.cnblogs.com/EasonJim/p/8072953.html