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I've been working on a LAN discovery tool with a Terminal User Interface (TUI) written entirely in Go. It's called Whosthere, and it's designed to help you explore devices on your local network without requiring elevated privileges.

It works by combining several discovery methods:

- mDNS and SSDP scanning

- ARP cache reading (after triggering ARP resolution via TCP/UDP sweeps)

- OUI lookups to identify device manufacturers

It also includes:

- A fast, keyboard-driven TUI (powered by tview)

- An optional built-in port scanner

- Daemon mode with a simple HTTP API to fetch devices

- Configurable theming and behavior via a YAML config file

Why I built it:

Mainly to learn, I've been programming in Go for about a year now and wanted to combine learning Go with learning more about networking in one single project. I've always been a big fan of TUI applications like lazygit, k9s, and dive. And then the idea came to build a TUI application that shows devices on your LAN. I am by no means a networking expert, but it was fun to figure out how ARP works, and discovery protocols such as mDNS and SSDP.

Example usage:

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# install via HomeBrew brew tap ramonvermeulen/whosthere brew install whosthere

# or with go install go install github.com/ramonvermeulen/whosthere@latest

# run as TUI whosthere

# run as daemon whosthere daemon --port 8080

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I'd love to hear your feedback, if you have ideas for additional features or improvements that is highly appreciated! Current platform support is Linux and MacOS.

There's a famous quote:

  Those who cannot remember nmap are condemned to remake it poorly

Rootless nmap scan of a /24 in under 10 seconds:

  nmap -T5 -sn -PR --script broadcast-dns-service-discovery,broadcast-upnp-info 10.0.0.0/24
  …SNIP…
  Nmap done: 256 IP addresses (30 hosts up) scanned in 9.99 seconds

https://nmap.org/book/toc.html

This is hilarious, 5 years ago I built a very similar cli tool based on the same idea and with the same name (whosthere but in Polish, ktotu [0]). I wonder if you used AI to generate the project and the idea

Congrats for the execution, it looks more complete and feature rich and Go is a better choice for sure

[0] https://github.com/jmaczan/ktotu

Overall good work. I'd request an `-i` command-line parameter to specify the interface to scan (and I'd prefer ALL params being able to be read from command line params). I think it just performs a full scan initially on my laptop, following scans either didn't success or didn't involve TCP connect scan (I don't see ARP requests after the initial scan).

Surely a missed opportunity to name it “whogoesthere”

Does the Go standard library have unusually good TUI support or something? Am I just imagining the pattern of new TUIs being written in Go?

Big missed opportunity to call it “Whose LAN is it anyway?”

Good skills - you are well on the way to Engineer with a capital E.

You cannot see network traffic.

You'd be amazed at how many people think they can diagnose a network fault without using tools like this. Everyone is an expert until they prove themselves to be a bit of a twit!

At layer 1 you have electrical issues to deal with and that will need some hardware. Obviously you need to pick your network model too. Here you'll go in with a couple of PCs/laptops and APIPA and/or a Fluke or a cheap network tester effort off of Amazon. Use what you have available.

After that you will need nmap and wireshark. LLDP and CDP are very handy too.

If you have to deal with a large network, I can highly recommend Netdisco.

Have you tried it on Tailscale at all? Could be super useful but sadly TS doesn't support mDNS: https://github.com/tailscale/tailscale/issues/1013

Good stuff, this saves me the trouble of going through router GUI. And remembering if it was 192.168.1.1 or 0.1 or what were the admin/root passwords.

I love the resurgence of TUI apps, but I wonder what the definition of "modern TUI" means in these cases. Does it basically mean just not using curses?

Love how all these "modern" TUIs are basically replicating Turbo Vision, Clipper and curses.

Using brew, I got "Apple could not verify `whosthere' is free of malware that may harm your Mac or compromise your privacy." [Move to Trash] [Done]

Busy building something similar with a view towards customising it for my LAN.

Specifically it needs to pull additional detail out of proxmox servers and opnsense plus deduce where things are physically based on latency.

Thats a whole lot easier if it doesn’t need to work universally & you can hardcode some assumptions

I'm also working on a Go TUI tool. Any reason you went with tcell instead of charmbracelet ecosystem?

Seems IPv4-only, which most LANs aren't since a good while.

I am not a golang user. If I install as recommended via `go` command on Linux how do I make sure it is updated when new versions are released? I wish it has a .deb package..

Great tool, I will test the tool

You forgot the most useful (and thus important) discovery tool of all:

  ping ff02::1%eth0

Great tool, only thing I miss is it doesn't show SAMBA names.

Looks nice. I'd love to have a way to select anything on the screen or at least have a button to copy more info, like manufacturer name of a found device.

It says 'Open ports: (None)' for all devices on my network, despite there being open ports on many of them (MacOS Tahoe 26.2 / installed via go)

Looks great. Discovery.app is also useful if you’re mostly dealing with Apple / Bonjour-heavy networks. https://apps.apple.com/us/app/discovery-dns-sd-browser/id138...

is the only way to export the results "run in daemon mode and curl yourself"?

- can we get a radmin vpn that works on both mac and windows?

I hope browsers could support mDNS or SSDP. We need an Intranet browser!

Neat! Others have pointed out nmap, but hey, a project may look similar at first but evolve into something entirely different. For a few years I have slowly worked on a network analysis tool. It started out as a way to learn a few concepts better, make a prettier TUI app, but has turned into a tool I use for work as needed. I have never shared it here, https://github.com/derekburgess/jaws

Love it! I already have some ideas for additional improvements, might jump in and contribute a PR or two.

Great work.

this is great! i had to tweak the config file on macos because it was using some weird interface (utun4) instead of en0. otherwise awesome tool, i am definitely going to be using this more often.

I read the title as "W host here"

> Apple could not verify “whosthere” is free of malware that may harm your Mac or compromise your privacy.

Couldn't run it on macOS Tahoe. I believe this requires me lowering the security to allow it, which is something I would rather not doing.