====== ipv6 ======
prefix length is first 64 bits

VT is 
  2001:468:c80::/48
Global is 
  2000::/3
IPv6to4 is 
  2002::/16
IPv6to4 for VT is 
  2002:80ad::/32
  2002:c652::/32
if these 2002 addresses appear, it could cause it to search 40 hops away.  Turn off IPv6to4

Link LocalL 
  fe80::/10
Multicast: 
  ff00:/8
All node Multicast: 
  ff01::
Multicast on link local 
  ff02::
loopback 
  ::1
[[http://rdweb.cns.vt.edu/wiki]]

[[http://www.sixxs.net]]

Good firefox plugin: showIP

[[http://www.kame.net]]

[[http://ipv6.vt.edu]]

host.dept.ip6.vt.edu -> AAAA

host.dept.vt.edu -> A

host4.dept.vt.edu used for ip4 addresses only

=== Common problems ===
2002:... addresses are for IPv6to4 gateways

If only fe80::, maybe router discovery is off

==== SixXS Subnet ====
[[http://www.ipv4.sixxs.net/wiki/Installing_a_Subnet]]

independence ~ # cat /etc/radvd.conf 
<file>
interface eth0
{
       AdvSendAdvert on;
       prefix 2001:4978:215::/64
       {
               AdvOnLink on;
               AdvAutonomous on;
               AdvRouterAddr on;
       };
};
</file>

for independence:
   ip addr add 2001:4978:215::1/64 dev eth0
   /etc/init.d/radvd start

Hostname:	uschi02.sixxs.net

This PoP provides tunnels from the following prefixes:
  * 2001:4978:f::/48 of size /64

Subnets are allocated out of:
  * 2001:4978:100::/40 of size /48
  * 2001:4978:200::/40 of size /48

address for independence as reported by ssh login from independence to riccioli:
  cl-734.chi-02.us.sixxs.net

for thinkpad-steve as reported by ssh login to riccioli:
  2001:4978:215:0:218:deff:fe4b:2569

  sixxs                        2001:4978:f:2dd::1 gw-734.chi-02.us.sixxs.net
  independence sixxs external  2001:4978:f:2dd::2 cl-734.chi-02.us.sixxs.net
  independence eth0 internal   2001:4978:215::1
  thinkpad wlan0               2001:4978:215:0:218:deff:fe4b:2569
  bacchus                      2001:468:c80:610c:230:48ff:fe8f:77dd/64
  chernabog.cc.ipv6.vt.edu     2001:0468:0c80:2105:0000:025e:42da:ffc7 (tried to connect using SPT=80)
  inbound.smtp.vt.edu          2001:468:c80:2106:0:240:5040:1614
  hephaistos                   2001:468:c80:610c:24f:4eff:fe0f:fd4a/64
  
==== crash course ====

http://www.linux.com/learn/tutorials/428331-ipv6-crash-course-for-linux

=== discover link local addresses ===
ff02::1 is short for ff02:0:0:0:0:0:0:1, which is a special link-local multicast address for discovering all link-local hosts
  $ ping6 -c4 -I eth0 ff02::1
=== IPv6 neighbor table ===
  ip -6 neigh show
nud reachable means the network unreachability detection status is reachable

=== Ping the addresses ===

  ping6 -c4 -I eth0  fe80::(rest of address)

/etc/hosts file of each PC:
  fe80::20b:6aff:feef:7e8d  fatfreddy
  fe80::221:97ff:feed:ef01  phineas
  fe80::3f1:4baf:a7dd:ba4f  franklin

Now you can ping6 by hostname:

  $ ping6 -I eth0 phineas

This is how you establish an SSH session:

  ssh phineas@fe80::221:97ff:feed:ef01%eth0

Again, you must specify the network interface name on your PC, and you must do it as shown, appended with a percent sign and no spaces. scp has its own fiendish syntax quirks:

  $ scp test.txt phineas@\[fe80::221:97ff:feed:ef01%eth0\]:
  phineas@fe80::221:97ff:feed: ef01%eth0's password:
  test.txt 100%   19     0.0KB/s   00:00 

The IPv6 address must be enclosed in square braces, including the interface name, and the braces must be escaped.

Let's fake one up for practice and assign it to a network interface:

  # ip -6 addr add 2001::1/64 dev eth0

Now let's check our work:

  $ ifconfig eth0 |grep "inet6 addr:"

          inet6 addr: 2001::1/64  Scope:Global
          inet6 addr: fe80::20b:6aff:feef:7e8d/64 Scope:Link

If you need to remove it, use the del command with the ip utility:

  # ip -6 addr del 2001::1/64 dev eth0

====  ====

http://www.linux.com/learn/tutorials/432537-another-ipv6-crash-course-for-linux-real-ipv6-addresses-routing-name-service
===  ===

these iptables rule block all IPv6 traffic from entering or leaving your LAN:

  ip6tables -P output drop
  ip6tables -p input drop
  ip6tables -p forward drop 


  2001:db8:0000:0000:0000:0000:0000:0001
  _____________|____|___________________
  network ID   subnet  interface ID

=== Routing (quoted directly from the article) ===

Your router must support IPv6, of course. If you're using a Linux PC as your test machine you're in business. First start IPv6 forwarding:

  # sysctl -w net.ipv6.conf.all.forwarding=1

Verify forwarding is enabled:

  # cat /proc/sys/net/ipv6/conf/eth0/forwarding
  1

A return value of 1 means it is enabled, 0 means it is not. Now install radvd, the router advertiser daemon. Then create /etc/radvd.conf with this simple configuration:

  interface eth0
  {
     AdvSendAdvert on;
     prefix 2001:db8::/64
     {
     };
  };

Copy it exactly, changing only the interface name if necessary. Now create an IPv6 address on your router, or PC acting as your router, and set an IPv6 route:

  # ip address add 2001:db8::1a/64 dev eth0
  # ip route add 2001:db8::/64 dev eth0

Check your work by running ifconfig and ip -6 route show. Your ip output should look similar to this:

  2001:db8::/64 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295
  2001:db8::/64 dev eth0 metric 1024 mtu 1500 advmss 1440 hoplimit 4294967295
  fe80::/64 dev eth0 proto kernel metric 256 mtu 1500 advmss 1440 hoplimit 4294967295

Finally, start up the radvd daemon:

  # etc/init.d/radvd start

You should now be able to ping the router from another PC. Note that unlike our link-local addresses, we don't need to specify the network interface:

  $ ping6 2001:0db8::1a

All of the computers on the same switch as your IPv6 router should have new addresses in the 2001:0db8::/64 range. You can look these up and go on a ping6 frenzy. A default gateway (for connecting to other networks) is the IPv6 address of your router:

  # ip -6 route add default via 2001:db8::1a

Of course it's less work to configure it in radvd.conf and have it advertised automatically by adding these lines:

  route ::/0
  {
  };

Then when you run ip -6 route show you'll see this:

  default via 2001:db8::1a dev eth0 metric 1024 mtu 1500 advmss 1440 hoplimit 0

What if you don't want radvd blasting IPv6 addresses all over your network? No worries, for you can limit its clients by listing their IPv6 link-local addresses like this:

       interface eth0
       {
               AdvSendAdvert on;
               prefix 2001:db8::/64
               {
                       AdvOnLink on;
                       AdvAutonomous on;
               };
               route ::/0
               {
               };
               clients
               {
                       fe80::20d:b9ff:fe05:25b4;
                       fe80::20b:6aff:feef:7e8d;
                       fe80::221:97ff:feed:ef01;
               };
       };

Mind your braces and semi-colons!