我有两台笔记本电脑： - Debian挤压的第一个，通过以太网连接，IP地址为192.168.0.2 - 第二个与Ubuntu 12.10通过wlan连接，并具有IP地址192.168.0.9
问题是： - 如果我尝试从第一个到第二个使用ssh，我得到这个结果：
laptop1@192.168.0.2:~$ ssh laptop2@192.168.0.9
"ssh : connect to host 192.168.0.9 port 22: No route to host "
如果我尝试从第二个到第一个使用ssh，它会成功连接到第一个。
laptop2@192.168.0.9:~$ ssh laptop1@192.168.0.1
现在，如果我再次尝试从第一个到第二个连接，它会成功连接到第二个
laptop1@192.168.0.2:~$ ssh laptop2@192.168.0.9
但是几分钟之后如果我尝试从第一个到第二个使用ssh，我仍然得到这个结果：
"ssh : connect to host 192.168.0.9 port 22: No route to host ".
在laptop1上键入命令arp我注意到，当laptop2的ip地址消失时，我无法从laptop1连接到laptop2。
laptop1@192.168.0.2:~$ sudo arp
Address HWtype HWAddress Flags Mask Iface
192.168.0.1 ether 00:1b:2f:3f:b5:a2 C eth0
192.168.0.9 ether e4:d5:3d:03:3b:ed C eth0
laptop1@192.168.0.2:~$ sudo arp
Address HWtype HWAddress Flags Mask Iface
192.168.0.1 ether 00:1b:2f:3f:b5:a2 C eth0
有人明白为什么会这样？我该如何解决？
我发布了我的两台笔记本电脑的更多信息：
为laptop1：
laptop1@192.168.0.2:~$ sudo ifconfig
eth0 Link encap:Ethernet HWaddr 20:cf:30:08:e0:82
inet addr:192.168.0.2 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::22cf:30ff:fe08:e082/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:29290 errors:0 dropped:0 overruns:0 frame:0
TX packets:28325 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:20301572 (19.3 MiB) TX bytes:11035023 (10.5 MiB)
Interrupt:30
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:1440 errors:0 dropped:0 overruns:0 frame:0
TX packets:1440 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:166450 (162.5 KiB) TX bytes:166450 (162.5 KiB)
wlan0 Link encap:Ethernet HWaddr 74:f0:6d:76:79:93
inet6 addr: fe80::76f0:6dff:fe76:7993/64 Scope:Link
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:42 errors:0 dropped:0 overruns:0 frame:0
TX packets:81 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:10888 (10.6 KiB) TX bytes:16236 (15.8 KiB)
laptop1@192.168.0.2:~$ sudo route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.0.0 0.0.0.0 255.255.255.0 U 1 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 eth0
0.0.0.0 192.168.0.1 0.0.0.0 UG 0 0 0 eth0
为laptop2：
laptop2@192.168.0.9:~$ sudo ifconfig
eth0 Link encap:Ethernet HWaddr 04:7d:7b:1e:47:8b
UP BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
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:124 errors:0 dropped:0 overruns:0 frame:0
TX packets:124 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:10373 (10.3 KB) TX bytes:10373 (10.3 KB)
wlan0 Link encap:Ethernet HWaddr e4:d5:3d:03:3b:ed
inet addr:192.168.0.9 Bcast:192.168.0.255 Mask:255.255.255.0
inet6 addr: fe80::e6d5:3dff:fe03:3bed/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:1434 errors:0 dropped:0 overruns:0 frame:0
TX packets:1329 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1274245 (1.2 MB) TX bytes:188474 (188.4 KB)
laptop2@192.168.0.9:~$ sudo route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 192.168.0.1 0.0.0.0 UG 0 0 0 wlan0
169.254.0.0 0.0.0.0 255.255.0.0 U 1000 0 0 wlan0
192.168.0.0 0.0.0.0 255.255.255.0 U 9 0 0 wlan0