我有一个 BeagleBone Black 板仅通过串行连接和以太网电缆连接到我的笔记本电脑，并由 5 毫米插孔供电。串行连接工作正常，我可以随时登录，但无法通过以太网连接进行登录。我的笔记本电脑上运行的是 Ubuntu 14.04。
ifconfig笔记本电脑端的输出是：
eth0 Link encap:Ethernet HWaddr 00:26:9e:54:39:db
inet6 addr: fe80::226:9eff:fe54:39db/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:30 errors:0 dropped:0 overruns:0 frame:0
TX packets:1102 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:12400 (12.4 KB) TX bytes:225290 (225.2 KB)
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:65536 Metric:1
RX packets:7615 errors:0 dropped:0 overruns:0 frame:0
TX packets:7615 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:764895 (764.8 KB) TX bytes:764895 (764.8 KB)
wlan0 Link encap:Ethernet HWaddr 0c:ee:e6:80:75:e4
inet addr:10.17.255.177 Bcast:10.17.255.255 Mask:255.255.240.0
inet6 addr: fe80::eee:e6ff:fe80:75e4/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:161592 errors:0 dropped:0 overruns:0 frame:57437
TX packets:133489 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:185045013 (185.0 MB) TX bytes:15021821 (15.0 MB)
Interrupt:16
在 BB 端通过串行通信：
eth0 Link encap:Ethernet HWaddr 90:59:AF:5C:D1:3E
inet addr:169.254.28.162 Bcast:169.254.255.255 Mask:255.255.0.0
inet6 addr: fe80::9259:afff:fe5c:d13e/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:535 errors:0 dropped:0 overruns:0 frame:0
TX packets:41 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:111890 (109.2 KiB) TX bytes:12586 (12.2 KiB)
Interrupt:56
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:65536 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:0
RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
usb0 Link encap:Ethernet HWaddr 76:09:06:0A:D5:77
inet addr:192.168.7.2 Bcast:192.168.7.3 Mask:255.255.255.252
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)
如果我跑route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
0.0.0.0 10.17.255.254 0.0.0.0 UG 0 0 0 wlan0
10.17.240.0 0.0.0.0 255.255.240.0 U 9 0 0 wlan0
我看不到我的板连接到 eth1 或类似的设备，也无法在没有 USB 或串行连接的情况下加载到 BeagleBone。
我错过了什么？