Running ifconfig eth0, there is one Global addr and also a Link addr of my NIC. What do they mean? I know the Global one is my "real" ip address.

    eth0      Link encap:Ethernet  HWaddr 28:d2:44:e6:9f:d4  
              inet addr:  Bcast:  Mask:
              inet6 addr: 2001:da8:8001:8000::2:91ef/64 Scope:Global
              inet6 addr: fe80::2ad2:44ff:fee6:9fd4/64 Scope:Link
              UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
              RX packets:56060 errors:0 dropped:0 overruns:0 frame:0
              TX packets:32740 errors:0 dropped:0 overruns:0 carrier:0
              collisions:0 txqueuelen:1000 
              RX bytes:68881613 (68.8 MB)  TX bytes:3285510 (3.2 MB)

A link-local address which is derived during stateless address auto-configuration (defined in RFC 4862) so that your computer can communicate on local networks without any information obtained from an external source (such as DHCP or IPv6 router solicitation/advertisement).

Unless manually configured, it is derived from the MAC address of the NIC in EIU-64 format (for Ethernet) and begins with FE80:: with a /64 prefix, and every NIC on a system will have one (by default).

  • Thanks for your reply but I have one more quetion to ask. – Jason Tao Mar 4 '16 at 15:30
  • is it related? if so, update your question – stevieb Mar 4 '16 at 15:31
  • There seems to be problems with my ISP's IPv6 service so it made my connection not stable. I have heard from others that the ISP router used DHCPv6 to allocate the IPv6 address. However, it used NDP to advertise packages. I am not really clear about the meaning of this. But if it is true, what should I configure on Ubuntu? I am using /etc/network/interfaces to configure my network. And it currently reads "iface eth0 inet6 dhcp". Should I alter it to static? – Jason Tao Mar 4 '16 at 15:39
  • how can I find the router's link-local address using my own computer? – Jason Tao Mar 5 '16 at 9:18

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