Weird ubuntu client appears connected to my ISP gateway using an IPv6 address

logui

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Feb 22, 2024
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I have Proxmox 8.2 installed on a Protectli appliance, OpenWrt is running as a VM, it is performing the Router functionality, upstream I have the ISP (T-Mobile Home Internet) gateway connected to the WAN port of OpenWrt, that's the enp3s0 ethernet port in Proxmox.

In the ISP gateway (it's a router as well, therefore I am double NAT), I can see all the client devices connected to it, in this case should be ONLY the OpenWrt router's MAC address, the one assigned by the network device in the VM, and that's correct. I have checked both MAC addresses and they are the same, also OpenWrt is assigned an IPv4 from the gateway's DHCP server and also multiple IPv6 addresses for all the client devices connected to the OpenWrt router, also the OpenWrt's hostname is registered correctly in the gateway. So far, as expected, all good.

The weird thing is, there is a second client connected to the gateway, it has ubuntu as it's hostname and the client's MAC address registered in the gateway, is the MAC address of the enp3s0 port, I checked that with the ip a command in the node's shell. This ubuntu client doesn't have an IPv4 assigned, only IPv6 ( fe80:: and 2607: ), sometimes I need the client connected and sometimes it's disconnected.

I know Proxmox uses or has used the Ubuntu kernel, that might be an explanation for the client's name? Is this something related to the way how Proxmox connects the physical port with bridges and with the VM's ethernet devices? Could it be a process running in the background at random times bypassing the OpenWrt VM?

Any previous experience or feedback will be appreciated, thanks

Update: I have noticed that when I execute the Node --> Updates --> Refresh --> Upgrade in the GUI Console (or # apt update from the console shell), the ubuntu server will show up, if I reboot the ISP's gateway, it will disappear (the list gets cleaned up on reboot), then I manually trigger the Upgrade from the GUI again, and it will immediately show up in the gateway, very weird, and it's only IPv6, no IPv4 address is assigned to the ubuntu client.
 
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