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Computers & Hardware => Networking => Topic started by: banger on September 09, 2017, 01:35:29 AM

Title: IPV6 6to4
Post by: banger on September 09, 2017, 01:35:29 AM: Trying to configure IPv6 on a non native 6to4 network on an Asus router. It worked on ipv6-test.com the other day but reloading the same settings it no longer works. Here are my settings

Connection type   6to4
IPv4 Anycast Relay
192.88.99.1
Tunnel MTU
1280
Tunnel TTL
255

I have a IPv6 LAN address and am using TBB BQM to ping it and it responds but I cannot browse any IPV6 sites or test sites say no IPV6 address advertised. Any thoughts?
Title: Re: IPV6 6to4
Post by: Chrysalis on September 09, 2017, 09:56:48 AM: sounds like the lan side dhcp6 and radvd is not working properly, so in short the router has ipv6 but the clients behind it do not.

Check if they enabled in the asus settings.
Title: Re: IPV6 6to4
Post by: banger on September 09, 2017, 11:40:53 PM: As far as I can tell the windows box has IPV6 connectivity but just simply doesn't work.

(https://i.imgur.com/gOCY2zp.png)
Title: Re: IPV6 6to4
Post by: smf22 on September 11, 2017, 03:44:54 PM: If you run ipconfig from the command prompt of the Windows client does it show an IPv6 Global Unicast Address and is this from the same range that you see on the router?

I'm assuming you don't want to run an IPv6 DHCP server on the Asus and will simply run SLAAC (Stateless Address Autoconfiguration) for the clients to get an IPv6 address? SLAAC is the simplest option and has the router advertising the IPv6 address prefix in an IPv6 Router Advertisement (RA) which are seen and used by the clients to determine the IPv6 address prefix they should use. I'm not sure how to do this on an Asus, but hopefully there's an option to enable SLAAC on the LAN interface.

If you have Wireshark installed on the Windows client you could try capturing the IPv6 RA as follows:

1. Open a command line prompt as Administrator
2. Enter cd C:\Program Files\Wireshark
3. Run the command ipconfig to get the name of the LAN interface on the client. In the example below mine is named "Home_LAN"

Code: [Select]
C:\Users\smf22>ipconfig Windows IP Configuration Ethernet adapter Home_LAN: Connection-specific DNS Suffix . : home IPv6 Address. . . . . . . . . . . : 2a00:23c5:xxxx:yyyy:a039:ce9f:e009:15ae Temporary IPv6 Address. . . . . . : 2a00:23c5:xxxx:yyyy:6d54:48c5:83eb:8895 Link-local IPv6 Address . . . . . : fe80::a039:ce9f:e009:15ae%5 IPv4 Address. . . . . . . . . . . : 192.168.1.78 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : fe80::46d9:e7ff:fe50:5b7e%5 192.168.1.1
4. Run the command tshark -V -i <interface_name> icmp6 and ip6[40]==134 to capture the IPv6 Router Advertisement. You'll need to change the <interface_name> to that you found in step 3.

What we're looking for is an ICMPv6 option specifying the IPv6 prefix, for example:

Code: [Select]
Ethernet II, Src: Ubiquiti_50:5b:7e (44:d9:e7:50:5b:7e), Dst: IPv6mcast_01 (33:33:00:00:00:01) Destination: IPv6mcast_01 (33:33:00:00:00:01) [snip] Internet Control Message Protocol v6 Type: Router Advertisement (134) Code: 0 [snip] Router lifetime (s): 1800 Reachable time (ms): 0 Retrans timer (ms): 0 ICMPv6 Option (Prefix information : 2a00:23c5:xxxx:yyyy::/64) Type: Prefix information (3) Length: 4 (32 bytes) Prefix Length: 64 Flag: 0xc0, On-link flag(L), Autonomous address-configuration flag(A) 1... .... = On-link flag(L): Set .1.. .... = Autonomous address-configuration flag(A): Set ..0. .... = Router address flag(R): Not set ...0 0000 = Reserved: 0 Valid Lifetime: 2592000 Preferred Lifetime: 604800 Reserved Prefix: 2a00:23c5:xxxx:yyyy::
Title: Re: IPV6 6to4
Post by: banger on September 11, 2017, 04:38:30 PM: Code: [Select]
Ethernet adapter Ethernet 4: Connection-specific DNS Suffix . : IPv6 Address. . . . . . . . . . . : 2002:****:****:0:9559:edde:8bc:bbfe Temporary IPv6 Address. . . . . . : 2002:****:****:0:751e:2364:b10b:b77a Temporary IPv6 Address. . . . . . : 2002:****:****:0:c9d1:7fdd:26af:3a43 Link-local IPv6 Address . . . . . : fe80::9559:edde:8bc:bbfe%13 IPv4 Address. . . . . . . . . . . : 192.168.1.54 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : fe80::e23f:49ff:fe97:436c%13 192.168.1.1
I got as far as ipconfig but got a bit lost with wireshark. I might just wait for Native IPV6 which is planned. Router advertisment is on in the 6to4 settings on the Asus.
Title: Re: IPV6 6to4
Post by: smf22 on September 11, 2017, 06:53:22 PM: I haven't played a lot with 6to4 as I have native IPv6, but reading around it seems that due to issues with 6to4 over the years, Operating Systems prefer IPv4 over 6to4.

From Section 3.5 Connection of IPv6 Domains via IPv4 Clouds (6to4) (https://tools.ietf.org/html/rfc7059#section-3.5)) of RFC 7059:

Quote
To avoid problems with 6to4, the IPv6 Default Address Selection algorithm [RFC6724] gives IPv4 addresses a higher preference than 6to4 addresses. When making a connection, a system will prefer native IPv6 over IPv4, and IPv4 over 6to4 IPv6. This causes 6to4 to be used only when a destination is not reachable over IPv4 and no other IPv6 connectivity is available.

There's a discussion Win7 seems to prefer IPv4 native to IPv6/6to4 - which is not what the policy table says - which is right? (https://social.technet.microsoft.com/Forums/windows/en-US/b4d504c8-2ae9-41f3-bf21-e2e5d7d9704f/win7-seems-to-prefer-ipv4-native-to-ipv66to4-which-is-not-what-the-policy-table-says-which-is?forum=w7itpronetworking) over at Microsoft that goes into a little more detail including a method to give 6to4 a higher priority.

So if the above is correct for your Windows client, you'll connect to any host that has both an IPv4 and IPv6 address via IPv4. You should use IPv6 for hosts that only have an IPv6 adress e.g., ipv6.google.com. So if you run ping -6 ipv6.google.com do you get a response?
Title: Re: IPV6 6to4
Post by: NewtronStar on September 11, 2017, 08:07:41 PM: Just tried that command on Windows 10 Pro sometimes it's hit & miss with 1 or 2 packets lost

Pinging ipv6.l.google.com [2a00:1450:4009:807::200e] with 32 bytes of data:
Reply from 2a00:1450:4009:807::200e: time=20ms
Reply from 2a00:1450:4009:807::200e: time=19ms
Reply from 2a00:1450:4009:807::200e: time=19ms
Reply from 2a00:1450:4009:807::200e: time=19ms

Ping statistics for 2a00:1450:4009:807::200e:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 19ms, Maximum = 20ms, Average = 19ms
Title: Re: IPV6 6to4
Post by: banger on September 11, 2017, 08:49:49 PM: C:\Users\x_ban>ping -6 ipv6.google.com

Yes I get a response so it looks like my Win 10 box is using IPv4 except when the only option is IPv6.

Pinging ipv6.l.google.com [2a00:1450:4009:804::200e] with 32 bytes of data:
Reply from 2a00:1450:4009:804::200e: time=23ms
Reply from 2a00:1450:4009:804::200e: time=23ms
Reply from 2a00:1450:4009:804::200e: time=23ms
Reply from 2a00:1450:4009:804::200e: time=23ms

Ping statistics for 2a00:1450:4009:804::200e:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 23ms, Maximum = 23ms, Average = 23ms

That will do me thanks, Newt and Steve. :)
Title: Re: IPV6 6to4
Post by: banger on September 11, 2017, 09:51:28 PM: And now IPV6-test.com works as well.
(https://forum.kitz.co.uk/proxy.php?request=http%3A%2F%2Fpreview.ibb.co%2Fk6vgwv%2F2017_09_11.png&hash=eb170c4b50741d783bb362091b6cf96dcc947437)