UPDATE 10/4 6:47 EDT
I have been going through all the comments. THANKS!!! I did not know about the techniques listed, so they are extremely helpful. Sorry for the slow update. As I mentioned below, I got behind with this yesterday so work cut into my evening.
I ran a port scan. The first syntax, -p, brought no joy. The nmap software itself suggested changing to -Pn. That brought an interesting response:
nmap -Pn 1-9999 <Local IP Addr>
Starting Nmap 7.93 ( https://nmap.org ) at 2024-10-04 11:44 BST
Failed to resolve “1-9999”. Nmap scan report for <Local IP Address> Host is up (0.070s latency). All 1000 scanned ports on 192.168.0.46 are in ignored states. Not shown: 990 filtered tcp ports (no-response), 10 filtered tcp ports (host-unreach) Nmap done: 1 IP address (1 host up) scanned in 6.03 seconds Just to be absolutely sure, I turned off my work computer (the only windows box on my network) and reran the same syntax with the same results.
As I read this, there is definitely something on my network running windows that is not showing up on the DHCP.
UPDATE 10/6
I am working through all these suggestions. I am sorry for the slow responses, but I have my hands full with family weekend. I will post more next tomorrow. But I did do one thing that has me scratching my head and wondering if this may be a wild goose chase.
I ran the nmap again per below with a completely fictional IP address within my normal range. It gave the exact same results:
nmap -A -T4 -p- -Pn <Fictional IP>
Starting Nmap 7.93 ( https://nmap.org ) at 2024-10-05 13:36 BST Nmap scan report for <Fictional IP>
Host is up (0.054s latency).
All 65535 scanned ports on <Fictional IP> are in ignored states.
Not shown: 65525 filtered tcp ports (no-response), 10 filtered tcp ports (host-unreach)
Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 182.18 seconds
Great Idea! My windows box is off and I can still see it from my phone.
Hmm
I’d maybe try systematically turning any other devices off you think could potentially have the grunt to run windows server in a container or VM.
Do you have a Mac/Linux machine handy? If you run
arp -ain one terminal and ping the unusual IP in another, that should give you a corresponding MAC address for the device. You can then look up the MAC address and see if it gives you any more info about the device running it—it might not but you never know. You can use something like https://dnschecker.org/mac-lookup.phpI guess next you could look at taking that MAC and blocking it in your router control panel and see if anything starts complaining
I love the “see who screams” method, my coworkers do not. it’s usually instant.
In addition, you might like to do a portscan on that IP address to see if any other ports reaveal something more interesting.
You can run this in cmd prompt, I think, if nmap is available on your windows machine:
nmap -p 1-9999 192.168.1.1IIS can only run on a windows OS, so it must be a windows physical machine or VM connected to your network.