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.
- 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:
---
# 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
---
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.
Installed on raspbian, works wonders, much better than the thing i vibecoded yesterday. One feature I'd like: recording new arrivals to a log with all the info so it can be used as a barebones IDS
This looks great! I've been searching for something like this for ever.
Some feedback of what I found on my network, as compared to some other scanners I've used.
I've never seen anything that can beat Advanced IP Scanner at finding hostnames. I've never even found a way to get arp or nmap to get close to Advanced IP Scanner; I've tried dozens of suggested commands of each, all with no luck. Here's the results of my scans:
Looks great!! I had the same idea a few days ago and am so glad you posted this now! I will be using it and will let you know of any feedback. So far works great on my network!
It would be great it it could show the reverse lookup of the IPs as on my LAN everything has a name and if it hasn't then it is probably an interloper!
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).
That's correct. To avoid overloading the local network, the initial scan has a built-in safeguard:
1. It only scans the subnet of the configured network interface.
2. The scan is limited to a maximum size of a /16 subnet.
3. It runs just once every 5 minutes (this interval should be made configurable, currently still hardcoded).
If a subnet larger than /16 is configured, whosthere will log a warning and only scan the first /16 portion of that subnet. As of now the network interface itself is configured via the YAML file. I agree it would be a good idea to add command-line flags for more of these settings to make them easier to adjust.
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..
Generally speaking, the Debian package management system is really not a place I would look for prompt updates when new versions of software are released.
Why not? It works roughly the same as any other binary distribution format. Given that the project is written in go, it's also unlikely to have many dynamically linked dependencies.
“go install” does not have an update mechanism. I imagine most people using it would consider such an anti-feature; it is not a package manager.
I certainly don’t want programs I “go install” to change underneath me without notice or review. That’s basically handing ownership of your computer to a remote developer.
No, it really doesn't have anything TUI focused in stdlib. I get the reason why but it would be cool if they had something foundational in golang.org/x/
This project appears to be using github.com/rivo/tview which is is really solid.
The charmbracelet folk are quite, um, charming, but when I tried to work with bubble tea on a multi pane project I found it unwieldy -- tview seemed much more straightforward.
Unsigned binaries on macOS have slowly but surely been marginalized more and more with scarier and scarier warnings and harder hoops to jump through. You can enable execution in the system settings “Privacy and Security” pane.
I’m sure this has nothing to do with Apple’s subscription-based (and government ID requiring) developer program membership which is the only way to get such signatures.
I started off using tview/tcell, and only later found out about bubbletea and the charmbracelet ecosystem. Then I didn't really find a solid reason to switch over to bubbletea. So far I really enjoyed the experience building the app with tview, the only real limitation I ran into was switching the theme at runtime, for which I had to build a custom mechanism.
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?
Yikes, so it's a "TUI" app... that still requires a display server? So I can't run this TUI over SSH or a virtual terminal. Wondering what the point of a tui is that still requires a gui environment to run?
Sorry, I was unhelpfully flippant. You totally can, and I don't want to distract from the great app that has been shared. This bug was just a compile time issue, which needed X libs to bake in clipboard support which is optional at runtime.
That has nothing to do with the UI framework. The X11 dependency comes as part of the clipboard integration (which I'd argue should be optional or even removed). Still, I wouldn't call it modern if Wayland is outright not supported.
I hesitated a bit bringing in this feature. On one hand, I really like to have clipboard support, on the other hand, I don't like that it requires you to change from static to dynamic linking (and have the x11 dependency).
Maybe I could write an install.sh script for installation that detects the OS and fetches the correct version/tarball from the Github release.
Thanks a lot for your contribution, this is something I will look into in the upcoming days. I totally agree that CGO isn't ideal, I had to make the build/release process also a lot more complicated purely for that clipboard requirement (see GHAs and the different goreleaser files).
On the other hand, I also don't want whosthere to be depended on a fork that isn't maintained anymore. I will think about this trade-off, but I am also interested how others look at this problem.
It doesn't start port scanning by default, maybe this is a feature I can build in the future. When you are on the `detail` view of a device, you can press `p` and that will open a pop-up to perform the port scan. Also the list of ports that will be scanned is a default list of common ports, and can be configured via the configuration yaml.
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.
Thanks, I am glad you like it! I couldn't find a Go API that just returns the OS "default" network interface, so struggled a bit with a correct implementation for that part.
When reading some blog posts, I found often a solution where it sends out an UDP dial to for example 8.8.8.8:53 because you can then get the network interface back from the connection it's local address. As fallback I implemented to pick the first non-loopback interface that is up.
Would be open to suggestions to do this in a better way!
this prints my Ethernet interface as expected. It doesn't make any requests, it just figures out where to route a packet. I guess it interfaces with the OS routing table.
Thanks for sharing! This is definitely something I will look into, I am all in favor to simplify the current implementation of finding the "default" OS network interface.
Would it help to get it on the "official" homebrew, instead of a custom tap/cask? Might try to do an application for that somewhere in the upcoming weeks.
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:
---
# 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
---
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.
Installed on raspbian, works wonders, much better than the thing i vibecoded yesterday. One feature I'd like: recording new arrivals to a log with all the info so it can be used as a barebones IDS
This looks great! I've been searching for something like this for ever.
Some feedback of what I found on my network, as compared to some other scanners I've used.
I've never seen anything that can beat Advanced IP Scanner at finding hostnames. I've never even found a way to get arp or nmap to get close to Advanced IP Scanner; I've tried dozens of suggested commands of each, all with no luck. Here's the results of my scans:
Alive hosts: 309
Unkown: 201
With hostnames: 80
https://www.advanced-ip-scanner.com/
####################################
I also tried a program called Angry IP Scanner:
Hosts scanned: 510
Hosts alive: 315
With hostnames: 75
https://angryip.org/
####################################
whosthere
Devices: 318
With hostnames: 54
Looks great!! I had the same idea a few days ago and am so glad you posted this now! I will be using it and will let you know of any feedback. So far works great on my network!
Very nice tool :-)
It would be great it it could show the reverse lookup of the IPs as on my LAN everything has a name and if it hasn't then it is probably an interloper!
Surely a missed opportunity to name it “whogoesthere”
I was thinking more along the lines of whodat
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).
That's correct. To avoid overloading the local network, the initial scan has a built-in safeguard:
1. It only scans the subnet of the configured network interface.
2. The scan is limited to a maximum size of a /16 subnet.
3. It runs just once every 5 minutes (this interval should be made configurable, currently still hardcoded).
If a subnet larger than /16 is configured, whosthere will log a warning and only scan the first /16 portion of that subnet. As of now the network interface itself is configured via the YAML file. I agree it would be a good idea to add command-line flags for more of these settings to make them easier to adjust.
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..
> I wish it has a .deb package..
Generally speaking, the Debian package management system is really not a place I would look for prompt updates when new versions of software are released.
Why not? It works roughly the same as any other binary distribution format. Given that the project is written in go, it's also unlikely to have many dynamically linked dependencies.
You might be confusing the .deb package format with the release cadence of the Debian Stable distribution.
“go install” does not have an update mechanism. I imagine most people using it would consider such an anti-feature; it is not a package manager.
I certainly don’t want programs I “go install” to change underneath me without notice or review. That’s basically handing ownership of your computer to a remote developer.
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?
It compiles fast, starts up fast, and doesn't have a ton of hoops to jump through (ie borrower/checker in rust).
No, it really doesn't have anything TUI focused in stdlib. I get the reason why but it would be cool if they had something foundational in golang.org/x/
This project appears to be using github.com/rivo/tview which is is really solid.
The standard library doesn't have much for this, but Bubble Tea https://github.com/charmbracelet/bubbletea is behind many of the better Go TUIs. This one is using https://github.com/rivo/tview.
The charmbracelet folk are quite, um, charming, but when I tried to work with bubble tea on a multi pane project I found it unwieldy -- tview seemed much more straightforward.
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]
It just means that the binary is not notarised. You can go into Privacy & Security to override.
Unsigned binaries on macOS have slowly but surely been marginalized more and more with scarier and scarier warnings and harder hoops to jump through. You can enable execution in the system settings “Privacy and Security” pane.
I’m sure this has nothing to do with Apple’s subscription-based (and government ID requiring) developer program membership which is the only way to get such signatures.
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
I'm also working on a Go TUI tool. Any reason you went with tcell instead of charmbracelet ecosystem?
I started off using tview/tcell, and only later found out about bubbletea and the charmbracelet ecosystem. Then I didn't really find a solid reason to switch over to bubbletea. So far I really enjoyed the experience building the app with tview, the only real limitation I ran into was switching the theme at runtime, for which I had to build a custom mechanism.
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
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.
is the only way to export the results "run in daemon mode and curl yourself"?
Big missed opportunity to call it “Whose LAN is it anyway?”
Great tool, only thing I miss is it doesn't show SAMBA names.
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?
It means it has a dependency on X11.
Yikes, so it's a "TUI" app... that still requires a display server? So I can't run this TUI over SSH or a virtual terminal. Wondering what the point of a tui is that still requires a gui environment to run?
Sorry, I was unhelpfully flippant. You totally can, and I don't want to distract from the great app that has been shared. This bug was just a compile time issue, which needed X libs to bake in clipboard support which is optional at runtime.
this stopped me from go installing it too on nixos. I'm not gonna put the effort in to run it.
There should be a build tag to disable clipboard, that'd be the easiest way around this.
That has nothing to do with the UI framework. The X11 dependency comes as part of the clipboard integration (which I'd argue should be optional or even removed). Still, I wouldn't call it modern if Wayland is outright not supported.
I think this is only a problem when building from source, right? It is indeed because of the dependency on https://github.com/golang-design/clipboard.
I hesitated a bit bringing in this feature. On one hand, I really like to have clipboard support, on the other hand, I don't like that it requires you to change from static to dynamic linking (and have the x11 dependency).
Maybe I could write an install.sh script for installation that detects the OS and fetches the correct version/tarball from the Github release.
That library isn't going to support Wayland any time soon, and requiring CGO isn't ideal IMO. See this bug, https://github.com/golang-design/clipboard/issues/6
How about this PR? https://github.com/ramonvermeulen/whosthere/pull/29
It switches to using github.com/dece2183/go-clipboard, which supports Mac, Windows, Linux (X11 + Wayland) and Android.
Thanks a lot for your contribution, this is something I will look into in the upcoming days. I totally agree that CGO isn't ideal, I had to make the build/release process also a lot more complicated purely for that clipboard requirement (see GHAs and the different goreleaser files).
On the other hand, I also don't want whosthere to be depended on a fork that isn't maintained anymore. I will think about this trade-off, but I am also interested how others look at this problem.
What's modern about Wayland?
I hope browsers could support mDNS or SSDP. We need an Intranet browser!
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)
It doesn't start port scanning by default, maybe this is a feature I can build in the future. When you are on the `detail` view of a device, you can press `p` and that will open a pop-up to perform the port scan. Also the list of ports that will be scanned is a default list of common ports, and can be configured via the configuration yaml.
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.
Thanks, I am glad you like it! I couldn't find a Go API that just returns the OS "default" network interface, so struggled a bit with a correct implementation for that part.
When reading some blog posts, I found often a solution where it sends out an UDP dial to for example 8.8.8.8:53 because you can then get the network interface back from the connection it's local address. As fallback I implemented to pick the first non-loopback interface that is up.
Would be open to suggestions to do this in a better way!
I think this package does exactly what you need: https://pkg.go.dev/github.com/google/gopacket/routing. Works on my machine (error handling left to the reader)
this prints my Ethernet interface as expected. It doesn't make any requests, it just figures out where to route a packet. I guess it interfaces with the OS routing table.Thanks for sharing! This is definitely something I will look into, I am all in favor to simplify the current implementation of finding the "default" OS network interface.
You'd better use the default route and not some random IP, particularly DNS IPs which people often meddle with.
> 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.
This is basically how every custom app works on Mac. You have to go to Settings -> Security & Privacy and click "Allow whosthere"
Would it help to get it on the "official" homebrew, instead of a custom tap/cask? Might try to do an application for that somewhere in the upcoming weeks.
this can be fixed by
xattr -c `which whosthere`