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Chris
Asked: 2015-05-16 04:24:26 +0800 CST

Disable DHCPv6 client in Windows

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I don't quite understand the link between 4 parameters related to IPv6 stateful and stateless autoconfiguration used under netsh int ipv6 set interface command context in Windows:

  • advertise
  • routerdescovery
  • managedaddress
  • otherstateful

From what I could find around so far, I understand that:

  • advertise is used to indicate that RA should be emited/responded by OS containing the M and O flag configured as managedaddress and otherstateful for that particular interface; this is relevant to a server.
  • routerdescovery is used to indicate that OS should request/process RA on that interface and use it to configure itself based on what flags the RA has; if routerdescovery is enabled, managedaddress and otherstateful are overridden by RA's flags; this is relevant to a client

My question is what happens when advertise and routerdescovery are disabled?

You would think that in this case, managedaddress and otherstateful determines whether or not DHCPv6 client is enabled or not on that interface. However, it doesn't seem to be so. If all 4 parameters are disabled (advertise, routerdescovery, managedaddress and otherstateful) Windows client will still try to contact a DHCPv6 server.

windows

1 Answers

  1. After many experiments and a lot of ambiguous docs and articles, I have deducted that managedaddress and otherstateful are relevant only in conjunction with advertise(i.e. when you enable RA on your Windows server) and they help setting the M and O flags in the RA packets.

    If routerdescovery is enabled and advertise disabled, you can't configure managedaddress and otherstateful parameters through netsh anymore, but as soon as an RA arrives on the interface, these two parameters are configured automatically so that they reflect the M and O flags of the arrived RA packet.

    Regardless which configuration is used, DHCPv6 Solicit messages are always sent on IPv6 enabled interfaces, even when receiving RA packets with M flag NOT set. I could not find a way to disable DHCPv6 on Windows (I assume Vista and above; I tested on 8.1). If there is a DHCPv6 server on the network you will get an IPv6 address from it.

    Luckily, most networks use stateless autoconfiguration (each node configure itself based on the prefix advertised in the RA) instead of stateful autoconfiguration where an IPv6 address is negotiated with a DHCPv6 server. Because most networks are stateless, many people thought that disabling routerdiscovery will stop them from getting additional IPv6 addresses. But this is not valid if there is a DHCPv6 server on the network.

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