While downloading a file with μTorrent, I noticed a strange peer with an address that was not an IPv4 or IPv6 address.

μTorrent showed it as WIN-F9PTTKUMI2U:29901.

What kind of address is this?


"What kind of IP address is this? (WIN-F9PTTKUMI2U:29901)"

WIN-F9PTTKUMI2U:29901 is not an IP address.

It identifies a socket connection of a particular μTorrent peer and has the format hostname:port.

  • WIN-F9PTTKUMI2U is the hostname.

  • 29901 is the port number.


The Peers tab is where you'll find information about all the peers you are currently connected to on the selected torrent. The following is a description of each column:

  • IP displays the peer's IP address and the flag of the country they're from. If Resolve IPs is enabled, the country flag and hostname will be displayed instead.

Source Peers

  • 10
    Indeed. It’s likely from the local network and a NetBIOS name. – Daniel B Nov 4 '14 at 16:02
  • 2
    It's not a particularly weird hostname either; recent Windows versions generate such names automatically, instead of asking during installation. – grawity Nov 4 '14 at 18:27
  • 13
    It's times like these where BitTorrent really needs built-in messaging capability so you can find the person on your same network with similar tastes in... Linux distribution ISOs. – Brad Nov 5 '14 at 1:38
  • 1
    @Brad What version of FreeBSD do you run? Did you even get it to work yet? – Kaz Wolfe Nov 5 '14 at 9:23
  • 1
    To be more specific, it isn't simply an address, it is a socket. The first part is a host name or address specifying which allows routing to the specific device, the second part is the port number which allows routing to the specific listening application. – MaQleod Jul 8 '15 at 16:56

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