問題：ping外網出現:
sendto: Network is unreachable
查看：
#route
Route命令 : 在數據包沒有有效傳遞的情況下，可以利用route命令查看路由表
[root@tiny4412:/]#route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.1.0 * 255.255.255.0 U 0 0 0 eth0
發現，是由於網關，沒有配置網關（gateway）
解決：
[root@tiny4412:/]#route add default gw 192.168.1.1 [root@tiny4412:/]#route Kernel IP routing table Destination Gateway Genmask Flags Metric Ref Use Iface default 192.168.1.1 0.0.0.0 UG 0 0 0 eth0 192.168.1.0 * 255.255.255.0 U 0 0 0 eth0
測試：
[root@tiny4412:/]#ping 119.75.217.56 PING 119.75.217.56 (119.75.217.56): 56 data bytes 64 bytes from 119.75.217.56: seq=0 ttl=50 time=20.468 ms 64 bytes from 119.75.217.56: seq=1 ttl=50 time=19.113 ms 64 bytes from 119.75.217.56: seq=2 ttl=50 time=18.814 ms 64 bytes from 119.75.217.56: seq=3 ttl=50 time=18.906 ms 64 bytes from 119.75.217.56: seq=4 ttl=50 time=18.859 ms 64 bytes from 119.75.217.56: seq=5 ttl=50 time=18.704 ms 64 bytes from 119.75.217.56: seq=6 ttl=50 time=19.050 ms 64 bytes from 119.75.217.56: seq=7 ttl=50 time=20.514 ms 64 bytes from 119.75.217.56: seq=8 ttl=50 time=21.355 ms ^C --- 119.75.217.56 ping statistics --- 9 packets transmitted, 9 packets received, 0% packet loss round-trip min/avg/max = 18.704/19.531/21.355 ms