networking – How do I traceroute an ipv6 address with mtr?

Using mtr installed via Homebrew on my Mac I received the above error.

However, I tried answering this on question on serverfault which has (at the time of this writing) 455 views, but this wasn’t possible as it was closed (off-topic), so I’ll answer it here due to the high interest:


Preface the command with sudo in addition to specifying the -6 switch:

sudo mtr -6 2001:db8:1d4f:10::1

That clears the error and mtr now functions as expected.

Disable IPv6 using CMD or Powershell on Windows 7

I’m trying to disable IPv6 connectivity on Windows using either command line or WMI api without restarting the computer (I know about adding an entry into Windows registry, but this requires rebooting the machine so it is not suitable). I know that unchecking ipv6 option in network adapter immediately disables it and I was able to achieve this via powershell commands such as Disable-NetAdapterBinding on newer Windows (8, 10) but Powershell on my Win7 VM reports unrecognized command for this. So the question is – is there another way to achieve the same thing (unchecking ipv6 option in network adapter) in Win7 using CMD or Powershell?

P.S. Disabling teredo, 6to4 and isatap via netsh utility also doesn’t work for me.

Can GSA use IPv6 proxies?

I searched and the last questionanswers about this was 2 years ago. Any updates? Is the current GSA compatible with IPv6 proxies? 
Thanks in advance.

The reason behind IPv6 adoption rate dramatical drop in China according to Google measurements?

Google has an IPv6 measurement page that reports that their numbers report on the percentage of users that access Google over IPv6.

According to the report by Jan 2020 0.3% of users in China used IPv6 to access Google

However, looking at this metric in dynamic we see the substantial drop starting from June 2019.
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I failed to find any solid news that may cause such behavior. I have two hypotheses in mind.

  1. Also as it is a percentage metric, they can adjust their calculation on the total internet penetration rate in China.
  2. Previously open discussions between netizens took place on Google Plus groups. In April 2019,
    Google shut down Google Plus. Technical discussions continue on
    Chinese-language blogs, forums, and groups. For obvious reasons,
    discussions must be hosted outside China, and posters must register under pseudonyms. So probably that caused the shift from Google services but I hardly believe that it may cause such plummet.

When will ipv6 completely replace ipv4?


some people start using ipv6,

Do you think when ipv6 will completely replace ipv4? … | Read the rest of

windows cannot reach to ipv4 mapped ipv6 address

I have a router with ipv4 and ipv6 address
inet addr: Bcast: Mask:
inet6 addr: fd76:5fda:1d05::1/60 Scope:Global
inet6 addr: fe80::ae84:c6ff:fe95:55b6/64 Scope:Link

and windows 10 client with

Connection-specific DNS Suffix . : lan
IPv6 Address. . . . . . . . . . . : fd76:5fda:1d05::afa
IPv6 Address. . . . . . . . . . . : fd76:5fda:1d05:0:c461:a76f:41e1:a385
Link-local IPv6 Address . . . . . : fe80::c461:a76f:41e1:a385%3
IPv4 Address. . . . . . . . . . . :
Subnet Mask . . . . . . . . . . . :
Default Gateway . . . . . . . . . :

on windows client , trying to reach router port 22(ssh) with IPV4 mapped IPV6 address fails
putty ::ffff: fails
putty :: fails
but linux
ssh root@::ffff: success
why?? need help.

Windows 7: Since IPv6 activation on Win7, VPN routing fails + DHCPv4 wired link fails

I have an ISP box connected to a Netgear WiFi router.

Internet <-->(WAN) ISP box (LAN)<-->(WAN) Netgear router (LAN)<-------> Win7 laptop
                           192.168.0.x/24                192.168.1.x/24

I successfully configured both of them to enable IPv6 connectivity to the internet (with the following IPv6 hops configured in the ISP box towards the WiFi router, whatever) Very happy, but I probably screwed some IPv4 stuff into the network layers of my computer Windows 7 laptop. I suspect they are corelated, but can't find the place 🙁

First, the Internet can be accessed through a laptop connected via WiFi, IPv4 (192.168.1.x / 24), and IPv6. I found out that although I can connect to a distant private network through VPN (Forticlient, username / password accepted and connection established), no traffic is received; any ping -4 to remote computers / routers fails:


Pinging with 32 bytes of data:
Request timed out.
Request timed out.
Reply from Destination host unreachable.
Request timed out.

Ping statistics for
    Packets: Sent = 4, Received = 1, Lost = 3 (75% loss),

Note that is my ISP (WiFi router gateway) box, no such IP exists on the remote network (VPN) where these packets are expected to go!


Windows IP Configuration

Ethernet adapter Local Area Connection 9:

   Connection-specific DNS Suffix  . :
   Link-local IPv6 Address . . . . . : fe80::b8a8:bf09:275c:682c%31
   IPv4 Address. . . . . . . . . . . :
   Subnet Mask . . . . . . . . . . . :
   Default Gateway . . . . . . . . . :
Wireless LAN adapter Wireless Network Connection:

   Connection-specific DNS Suffix  . : lan
   IPv6 Address. . . . . . . . . . . : 2a01:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx
   IPv6 Address. . . . . . . . . . . : 2a01:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx
   IPv6 Address. . . . . . . . . . . : fd69:cdc6:cb9d::a6b
   IPv6 Address. . . . . . . . . . . : fd69:cdc6:cb9d:0:bcac:ce5b:6ae4:4caf
   Temporary IPv6 Address. . . . . . : 2a01:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx
   Temporary IPv6 Address. . . . . . : fd69:cdc6:cb9d:0:7d0a:715c:58db:8656
   Link-local IPv6 Address . . . . . : fe80::bcac:ce5b:6ae4:4caf%12
   IPv4 Address. . . . . . . . . . . :
   Subnet Mask . . . . . . . . . . . :
   Default Gateway . . . . . . . . . : fe80::xxxx:xxff:fexx:xxxx%12

The routing table looks normal:

C:Windowssystem32>route print -4
Interface List
 31...00 09 0f aa 00 01 ......Fortinet SSL VPN Virtual Ethernet Adapter
 30...00 09 0f fe 00 01 ......Fortinet virtual adapter
 24...xx xx xx xx xx xx ......Intel(R) Ethernet Connection I218-LM #3
 16...xx xx xx xx xx xx ......Microsoft Virtual WiFi Miniport Adapter #2
 14...xx xx xx xx xx xx ......Bluetooth Device (Personal Area Network)
 12...xx xx xx xx xx xx ......Intel(R) Dual Band Wireless-AC 7260
  1...........................Software Loopback Interface 1

IPv4 Route Table
Active Routes:
Network Destination        Netmask          Gateway       Interface  Metric
     10 << Default route         On-link    306         On-link    306         On-link    306
          a.b.c.d     10 << VPN server @ a.b.c.d         On-link    266         On-link     10 << WiFi router         On-link    266 << WiFi address         On-link    266      1 << Remote net      1 << Remote net         On-link    257 << VPN connection         On-link    306         On-link    266         On-link    257         On-link    306         On-link    266         On-link    257
Persistent Routes:

Then I noticed that when I disable the laptop's WiFi and connect an Ethernet cable between the laptop and the router's LAN switch or ISP box, the laptop can't get an IPv4 address (remains APIPA 169.254.x.x).

According to Wireshark, it seems to send a DHCP request repeatedly but no response is received. Traffic from other devices on the LAN looks good in the Wireshark trace.

I tried ipconfig / release then / new without further success. May it be necessary to use more intrusive methods to reset the IPv4 stack to a cleaner state?

I tried all those tests on another Win7 laptop - it didn't find any such problems.

  • The VPN connection is fine, ping is successful.
  • The routing table is similar (with a few different IP addresses, as expected).
  • The wired connection gets an IP address without delay.

All of this assumes that the problem really lies with the first laptop (and not the router). But now I need your help to investigate further ...

networks: adding a public IPv6 address to a Linux virtual machine on Azure

I have an instance of Centos7 VM running on Azure. It has a public IPv4 address accessible from the internet. I would like to add a public IPv6 address to the network interface of this instance, but I cannot understand how to do it. There doesn't seem to be a way to add it to the interface from the portal. I have consulted the documentation but it seems to have conflicting information suggesting that it is not possible, or that it can only be achieved by creating a new VM. I have tried this too but again I couldn't get it to work. The information that I found on Google seems to be outdated.

I would greatly appreciate if someone could advise if it is possible to have public IPv4 and IPv6 addresses assigned to the same VM, and if so, how this could be accomplished. Thank you!

shortcut: DirectAccess management issues with native IPv6 implementation

I am trying to understand why my internal network machines cannot RDP on my DirectAccess clients. My internal network is in IPv6, so there is no ISATAP working. Only direct routes to and from clients. ping DA clients from my management devices on the internal network without problems. But when I try RDP directly on one of the DA clients, I can't connect. Clients accept RDP connections.

To discard the Windows firewall, I configured general permission rules on the admin PC, DA server, and remote client I am testing.

I used wireshark to investigate and discovered that the DA server receives the RDP connection request in 3389 with the correct IPV6 source from the management computer and the correct IP-HTTPS IPV6 tunnel address from the DA client.

I can't read the traffic beyond that as it is encrypted in the IP-HTTPS tunnel, but I don't see any connection attempt to login to the Windows firewall on the remote client.

I can establish an RDP connection directly from the DA server.

I don't know where to go from here and would appreciate someone providing assistance.

If you need more information, let me know what you need and I will receive it.

domain name system – IPv4 to IPv6 Migration Tip

I am currently working to add IPv6 capabilities to our network, and I have some questions about what is considered the best practice in 2020 to convert some of the IPv4 concepts that we are used to in the IPv6 world.

In the current configuration I have, the ISP assigns us a / 64, and the router announces that prefix for clients to configure using SLAAC. This seems to be working fine and to my knowledge everyone has access to IPv6 internet.

However, we like being able to query things by name, and I'm not sure what the best practice is to provide AAAA records for customers.

What I've done is implement stateful DHCPv6 in the dnsmasq instance running our DHCPv4 and tell it to deliver ULA of some range which naturally provides AAAA records for anyone requesting an address. This also seems to work fine, but I know there is some aversion to stateful DHCPv6. This also helps me to consolidate the allocation of the servers we have on static IPs exactly as I do for DHCPv4, these servers for various reasons must be accessible on a fixed IP address and we would like that to be the case for IPv6.

The only other way I can think of to do AAAA records is to send the RA prefix to the dnsmasq machine from the router via unicast and then use dnsmasq to advertise the GUA prefix to slaac using the ra-names option. However, this would not resolve static address mappings, as far as I can tell, and I am not sure how trustworthy it really is. Is there a better way to handle internal AAAA records than ULAs with stateful DHCPv6?

Finally, as things start to work, we are now looking to migrate our public services to IPv6. I understand that this would require a fixed GUA for servers to provision public AAAA records. I'm not sure how to accomplish this using SLAAC from the edge router, unless there is some kind of dynamic dns. Can I reuse DHCPv6 or another manual allocation method to choose IP in our assigned prefix? I was hesitant to do this because I thought it might collide with an SLAAC address and I'm not sure what happens if there is a collision. Alternatively, I have the option to ask the ISP for a / 48, Should I do that and advertise a single / 64 for local clients for connectivity and a different / 64 for static servers? This seemed excessive to me, since we did not get to fill the single / 64, but this could be my IPv4 mentality that confuses me.