Why is syncthing connecting to so many IPs?

Hey there,

why is Syncthing connecting to so many IPs? I thought I would have a safe home server, but then I saw this in the resource monitor of my windows 11 machine.

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If you are only syncing within your home network, and you have no need for any external relay, is only “Local Discovery” checked in your “Actions” “Settings” Connections tab?

Also: I can’t really tell from the OP’s screen shot, but if those unknown IP’s are in the 169.254.xx.xx range, then they are the so-called zero-conf IP’s used by avahi-autoipd IPv4LL, in the “Dynamic Configuration of IPv4 Link-Local Addresses” (RFC-3927), a protocol for automatic IP address configuration from the link-local 169.254. 0.0/16 range without the need for a central server. It is primarily intended to be used in ad-hoc networks which lack a DHCP server. They also can appear when a DHCP server does not respond quickly enough for an avahi enabled system.

In any event: They are local routed only and do not propagate on the global Internet. So no need to worry about them.

Other than the why are they on my DHCP enabled network… And which system did they originate from? I frequently see them coming from a transient Cell Phone seeking a WiFi connection.

Might be caused by Syncthing announces address of interface which is down · Issue #7458 · syncthing/syncthing · GitHub