Show HN: Flipflop – Iroh-powered persistent tunnels for filesharing
This is a project that spun from my frustrations of using LocalSend and DashBeam to transfer stuff between devices, and with the extra goal of being fast, trying out the Slint framework and, most importantly, establishing a communication channel with trusted external people that can be left always on.
98 points by andunie - 56 comments
Because Apple hates the world even more, I can't publish it for iOS."
Gold
The heavy lifting is done in this function, pairing. You link your personal devices together, solid idea [0].
This Flipflop project relies on the Iroh library for NAT/Firewall puncturing, external address discovery and overlay networking. Connecting two 5G devices, without a coordinating central server is possible, but very hard. Iroh simply relies on a server which you could self-host. Cool stuff, we stress tested it a while ago and it somewhat worked.
NAT connectivity is unsolved. My university lab conducted one of the bigger puncturing studies a decade ago [1]. Recently, we also bought 40+ or something 4G and 5G SIM cards in Europe for puncturing [2]. My master student traveled Europe by bus to get these local SIM cards. He worked day-and-night to connect these weird symmetric 5G NAT filter boxes and got it working. Simple sync collision and birthday paradox brute force... It all works sometimes, but insufficiently reliable for mass-adoption. You can't build a decentralized social media ecosystem on top. Like Iroh, best to use a central server. So then you have legal liability for your users. Unless an AI agent buys the server fully autonomously using Bitcoin, next years students got that working[3] :-)
[0] https://github.com/andunieee/flipflop/blob/62bb498520aacb60e...
[1] UDP NAT and Firewall Puncturing in the Wild, https://inria.hal.science/hal-01597969v1/document
[2] Mass Adoption of NATs: Survey and experiments on carrier-grade NATs, https://arxiv.org/html/2311.04658v2
[3] Self-replicating seedbox servers using programmable money, https://arxiv.org/abs/2609.05431
So if you are in an extremely weird NAT you will fall back to a relay, either our public relays, your own relays rented from us via iroh services, or a self-hosted relay.
But I would argue that a p2p social application that occasionally uses a relay is very much preferable to a centralised app.
The relay is generic internet infrastructure. It just forwards end to end encrypted connections. It can not learn anything about the content.
A relay that is hosted on a non KYC server rented via ZCash would be interesting though if you are super paranoid.
By 2030 we hopefully understand the mathematics-of-trust and can link all the billions of citizens together in a single overlay.
> non KYC server rented via ZCash would be interesting though if you are super paranoid.
What will happen if a decentralized Internet emerged and presented an existential threat to existing profit margins? Company lawyer would start to attack you, correct?
I think it's very misplaced concern. Commercially-viable internet will not be decentralized because of legal restrictions. If whatever engineering solution will be found to weaken them, governments will step in to curtail it. FWIW any moderately successful decentralization effort is more likely to be attacked from exactly this side: some countries will hate it for uncontrolled information dissemination, others for fiscal reasons.
You can, ATProto has the example schematics for how, but it's has a federated rather than distributed architecture, but I don't think "federation" is a hard constraint of the design, more like an implementation detail, and as long as you can do the signalling centrally, to connect the peers, you can do the rest P2P. So sure, legal liability for the connection of peers, but all data transfers would still be directly P2P. AFAIK, Iroh also does "Centralized signaling > P2P data transfers", even when NAT is in the way.
Nice idea with the browser link to share with devices that dont have flipflop on the same LAN. This would be a killer if this would also work via internet! Not sure if Iroh can run in the browser though.
I never tried Iroh in the browser, but supposedly it works (by always using a relay).
> filesharing for the meatspace era
serious question: what does this mean lol
May I ask, was it vibed/LLM-assisted to some extent, or is it purely human-made?
https://www.iroh.computer/sendme
But it's more for when you already use Tailscale, which relies on a central server and someone who "owns" that network.
In Flipflop you don't need anything besides the app, and each two peers form a "network" of their own, with no owner and no management.
Tailscale connections are peer-to-peer. They only own the coordination server, which you can ignore and host your own.
For some cases that is good, but Flipflop is addressing a slightly different use case.
I would argue that Tailnet is a good match for this.
Maybe expand the readme to cover other use cases interesting to existing Tailscale users?
I guess it's a bit like comparing WeTransfer with Airdrop, one tries to use the network they're on already (internet) where the other favors local-local connections.
Tailscale hosts relay servers as a fallback. Connections are peer-to-peer between devices.
Beyond that, even with a local connection established, all the coordination traffic will still go via the tailnet, those don't suddenly become local-first. But this might also have changed.
What I'm sure is still there today, is that all Tailscale clients automatically upload their logs to Tailscale's servers unless you opt out:
> Each Tailscale agent in your distributed network streams its logs to a central log server (at log.tailscale.com). This includes real-time events for open and close events for every inter-machine connection (TCP or UDP) on your network. - https://tailscale.com/docs/features/logging
Of course, doesn't stop a local connection from working so is only tangentially related, but worth keeping in mind that a "local tailscale connection" still has a lot of external traffic related to it, even though the data you transfer, when possible, uses more local connections.
1. The co-ordination server for the initial handoff. You can self-host if you want
2. Derp relays (for actual traffic). you can also self-host (peer relays)
Actually if self-hosting is that important to you, there are also newer solutions like netbird and netmaker that might worth a look.
Yes, as I noted, those differences wouldn't stop you from sending data locally. But since parent originally requested how they're different (without stating what exactly is important for them), I figured it is important at least to note what actually is the difference between taildrop and Flipflop.
It'd seem then if you wanted "local-first P2P transfer", with taildrop you'd need ~3 separate services running, unless I misunderstand you? Flipflop seems to do all those things in one package, although again, signaling (for NAT punching) is still via a central server.
Tailscale is super popular with people that have a homelab or nas/cameras/photos etc, and they have already solved the NAT problem (which iroh itself markets).
I would think this could be done completely in the browser using WebRTC?
But iroh is designed bare metal first, we currently support the browser via WASM, but only with relay mode.
We will solve browser eventually, but I think it is a mistake to build peer to peer tech browser first. We think it is better to make it extremely efficient on bare metal first, and then grow into the restricted browser ecosystem where possible.
Browsers are very restricted environments.
P2P is better then TURN/Iroh Relay. Even if traffic is encrypted the size of what you are passing through is valuable metadata. Or the time at what you send things. P2P is always better for users.
i've been pretty interested in this as well and got this snippet from chatgpt: `So could Iroh add direct browser-to-native connections without a proxy? Yes, by adding WebRTC support to the native side as well. Iroh’s own browser roadmap describes that approach and identifies the additional native WebRTC stack as a significant dependency cost. It does not describe a fundamental impossibility.`
i may take a stab at adding this functionality soon
A list of iroh based tools are also found here https://github.com/n0-computer/awesome-iroh