I have a Windows Server at a data center which has a range of IPv6 addresses, for example 2000:5300:120:e5e:: (not real address) with 64 entered in the Subnet Prefix Length. I want to bind one of the available IP addresses on an Icecast stream server, such as 2000:5300:120:e5e::1 but it fails to bind. If I set the Icecast server to bind to 2000:5300:120:e5e:: then it works. Can someone please explain why I can't use just one of those millions of addresses to bind to?

  • You may have the subnet routed to you, but did you also add every single address you want to use on a network interface?
    – Daniel B
    Jan 31 at 8:01
  • No, I've only added the entire subnet to the interface. I thought that would enable use of any of them.
    – Ross
    Jan 31 at 8:13
  • 1
    You cannot add a subnet. You can only add addresses, with varying subnet masks.
    – Daniel B
    Jan 31 at 8:27

1 Answer 1


Except in advanced use cases (high availability with failover), software can only bind to local addresses. A local address is an address that is assigned to one of the network interfaces of the operating system running the software.

You currently have one address assigned, 2000:5300:120:e5e::. This may look like it’s some kind of special address or even the entire subnet, but it’s not. It’s just the short form of 2000:5300:0120:0e5e:0000:0000:0000:0000.

If you want Icecast to listen on 2000:5300:120:e5e::1, you must explicitly add this address to the appropriate network interface. You must do this with any address you want to use.

The subnet being routed to your server does not hold any special meaning, it just allows you to use it.

  • All-zeros is the "Subnet-Router Anycast" address, which might have confused OP into thinking it magically listens on the entire subnet. (In reality it's the address that all routers within that subnet answer to.) Jan 31 at 9:16
  • I didn't realize I would need to add all the individual IPv6 addresses I would ever want to use into the Windows IPv6 Network Properties. It's a shame you can't just add the whole lot in one entry.
    – Ross
    Jan 31 at 23:22

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