I'm running a Windows server and trying to get it to use a static IPv6 address for outgoing connections to other IPv6 hosts (such as Gmail). I need this because Gmail requires a ptr record, and I can't set one for random addresses.
The static address is configured on the host, but it also has a temporary privacy address as well as a random address from the router it seems. By default Windows uses the privacy address; it seems this is the expected behavior (and it makes perfect sense for people/users that did not set a static address, but I did!).
I've tried disabling the privacy address with:
netsh int ipv6 set privacy disabled
This indeed gets rid of the privacy address, but I still have the random address that the router assigned. To disable this, it was said I needed to disable "router discovery" using this command:
net interface ipv6 set interface 14 routerdiscovery=disabled
Upon doing this, all IPv6 connectivity is lost. If I do this while pinging Gmail, it will report "Destination host unreachable" as soon as I enter the command. In the static IPv6 configuration, I did configure the default gateway and prefix length, so I don't see why it's unable to connect. Probably has something to do with the lack of ARP in IPv6 and somehow being unable to resolve the router's MAC, but I wouldn't know how to fix this.
Finally I've tried disabling the DHCPv6 lease with these commands:
netsh interface ipv6 set interface "IDMZ Team" managedaddress=disabled
netsh interface ipv6 set interface "IDMZ Team" otherstateful=disabled
Which was to no avail; the host continues to obtain and use the router-assigned IPv6 address.
The router is a FritzBox 7340, which shows me all the IPv4 and IPv6 addresses that the host (identified by MAC) utilizes, but I'm unable to change the assigned address. Maybe this could be done over the telnet interface of the router somehow, but again, I wouldn't know how to do this even if it's the way to go.
In short, any of the following would probably solve my problem:
- Change Windows' source address selection behavior.
- Have Windows not get an address from the router and not generate a privacy address;
- Have the router hand out a static address and make Windows use that as source address.
- Recover connectivity after disabling router discovery on Windows.
Alternatively I might use some (batch, perl, ...) script to throw away all IPv6 addresses except the desired one, but this feels rather hacky. If it's the only way (or less hacky than another hacky solution), it might be an option though.
Thanks!
Answer
The 'random address from the router' is probably your EUI-64 address, which is based on your MAC address. So it is probably not random and will stay stable over time (until you change hardware). Compare your MAC address to your IPv6 address. If your MAC address is 01:23:45:67:89:ab then your IPv6 address will end in ...:0323:45ff:fe67:89ab. You could add a PTR record for that address as well.
But I would like to suggest another solution: if you are sending mail directly to the receiver's mail server then you are running mail server software. You should be able to bind that server software to specific IP addresses. That way your mail server will always use the configured address when making outbound connections, while all other software can use whatever addresses are available on your host (static, autoconf, DHCPv6, privacy etc)
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