（1）ping www.baidu.com [ping: unknown host www.baidu.com]---（2）xshell 连接虚拟机问题---（3） 网卡重启失败

================================================[root@cdh1 hadoop]# ping www.baidu.comping: unknown host www.baidu.com[root@cdh1 hadoop]# ping 192.138.3.103PING 192.138.3.103 (192.138.3.103) 56(84) bytes of data.^C--- 192.138.3.103 ping statistics ---5 packets transmitted, 0 received, 100% packet loss, time 4264ms[root@cdh1 hadoop]# ping 192.168.3.103PING 192.168.3.103 (192.168.3.103) 56(84) bytes of data.64 bytes from 192.168.3.103: icmp_seq=1 ttl=128 time=1.81 ms64 bytes from 192.168.3.103: icmp_seq=2 ttl=128 time=10.4 ms64 bytes from 192.168.3.103: icmp_seq=3 ttl=128 time=0.329 ms64 bytes from 192.168.3.103: icmp_seq=4 ttl=128 time=0.741 ms64 bytes from 192.168.3.103: icmp_seq=5 ttl=128 time=0.588 ms64 bytes from 192.168.3.103: icmp_seq=6 ttl=128 time=0.284 ms64 bytes from 192.168.3.103: icmp_seq=7 ttl=128 time=0.607 ms64 bytes from 192.168.3.103: icmp_seq=8 ttl=128 time=0.583 ms^C--- 192.168.3.103 ping statistics ---8 packets transmitted, 8 received, 0% packet loss, time 7279msrtt min/avg/max/mdev = 0.284/1.923/10.447/3.252 ms[root@cdh1 hadoop]# ifconfigeth0      Link encap:Ethernet  HWaddr 00:0C:29:A8:1F:63            inet addr:192.168.3.110  Bcast:192.168.3.255  Mask:255.255.255.0          inet6 addr: fe80::20c:29ff:fea8:1f63/64 Scope:Link          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:2393 errors:0 dropped:0 overruns:0 frame:0          TX packets:980 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:1000           RX bytes:203735 (198.9 KiB)  TX bytes:118517 (115.7 KiB)          Interrupt:19 Base address:0x2000 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:5252 errors:0 dropped:0 overruns:0 frame:0          TX packets:5252 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:0           RX bytes:627383 (612.6 KiB)  TX bytes:627383 (612.6 KiB)virbr0    Link encap:Ethernet  HWaddr 16:49:39:3D:E6:49            inet addr:192.168.122.1  Bcast:192.168.122.255  Mask:255.255.255.0          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:0 errors:0 dropped:0 overruns:0 frame:0          TX packets:26 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:0           RX bytes:0 (0.0 b)  TX bytes:4189 (4.0 KiB)[root@cdh1 hadoop]# cat /etc/sysconfig/network-scripts/ifcfg-eth0DEVICE="eth0"HWADDR="00:0C:29:A8:1F:63"NM_CONTROLLED="yes"ONBOOT="yes"BOOTPROTO=staticIPADDR=192.168.3.110NETMASK=255.255.255.0GATEWAY=192.168.3.1[root@cdh1 hadoop]# cat /etc/resolv.conf # Generated by NetworkManager# No nameservers found; try putting DNS servers into your# ifcfg files in /etc/sysconfig/network-scripts like so:## DNS1=xxx.xxx.xxx.xxx# DNS2=xxx.xxx.xxx.xxx# DOMAIN=lab.foo.com bar.foo.com[root@cdh1 hadoop]# vim /etc/resolv.conf [root@cdh1 hadoop]# cat /etc/resolv.conf # Generated by NetworkManager# No nameservers found; try putting DNS servers into your# ifcfg files in /etc/sysconfig/network-scripts like so:## DNS1=xxx.xxx.xxx.xxx# DNS2=xxx.xxx.xxx.xxx# DOMAIN=lab.foo.com bar.foo.comnameserver 8.8.8.8nameserver 114.114.114.114[root@cdh1 hadoop]# cat /etc/sysconfig/network-scripts/ifcfg-eth0DEVICE="eth0"HWADDR="00:0C:29:A8:1F:63"NM_CONTROLLED="yes"ONBOOT="yes"BOOTPROTO=staticIPADDR=192.168.3.110NETMASK=255.255.255.0GATEWAY=192.168.3.1[root@cdh1 hadoop]# vim /etc/sysconfig/network-scripts/ifcfg-eth0[root@cdh1 hadoop]# cat /etc/sysconfig/network-scripts/ifcfg-eth0DEVICE="eth0"HWADDR="00:0C:29:A8:1F:63"NM_CONTROLLED="yes"ONBOOT="yes"BOOTPROTO=staticIPADDR=192.168.3.110NETMASK=255.255.255.0GATEWAY=192.168.3.1DNS2=114.114.114.114DNS1=8.8.8.8[root@cdh1 hadoop]# ping www.baidu.comPING www.a.shifen.com (119.75.218.70) 56(84) bytes of data.64 bytes from 119.75.218.70: icmp_seq=1 ttl=56 time=7.79 ms64 bytes from 119.75.218.70: icmp_seq=2 ttl=56 time=8.07 ms64 bytes from 119.75.218.70: icmp_seq=3 ttl=56 time=7.30 ms64 bytes from 119.75.218.70: icmp_seq=4 ttl=56 time=9.77 ms64 bytes from 119.75.218.70: icmp_seq=5 ttl=56 time=8.49 ms64 bytes from 119.75.218.70: icmp_seq=6 ttl=56 time=14.9 ms64 bytes from 119.75.218.70: icmp_seq=7 ttl=56 time=9.98 ms64 bytes from 119.75.218.70: icmp_seq=8 ttl=56 time=9.09 ms64 bytes from 119.75.218.70: icmp_seq=9 ttl=56 time=11.0 ms64 bytes from 119.75.218.70: icmp_seq=10 ttl=56 time=28.3 ms64 bytes from 119.75.218.70: icmp_seq=11 ttl=56 time=5.94 ms64 bytes from 119.75.218.70: icmp_seq=12 ttl=56 time=5.62 ms^C--- www.a.shifen.com ping statistics ---12 packets transmitted, 12 received, 0% packet loss, time 21194msrtt min/avg/max/mdev = 5.621/10.534/28.306/5.859 ms[root@cdh1 hadoop]# ================================================

SSH error:a public key file has not been specified by this sessionxshell 连接失败   /etc/ssh/sshd_config的PasswordAuthentication项为yes，重启服务（service sshd restart）