LittleSnitch for Linux

(obdev.at)

596 points | by pluc 7 hours ago

51 comments

  • alhazrod 7 hours ago
    I remember before Little Snitch there was ZoneAlarm for Windows[0] (here is a good screenshot[1]). No clue if the current version of ZoneAlarm does anything like that (have not used it in 2 decades). I always found it weird that Linux never really had anything like it.

    [0]: https://en.wikipedia.org/wiki/ZoneAlarm

    [1]: https://d2nwkt1g6n1fev.cloudfront.net/helpmax/wp-content/upl...

    • JetSetIlly 2 hours ago
      I wrote a program similar to this for AmigaOS many, many years ago. I would have been inspired by ZoneAlarm or a program like it.

      I've just found it and uploaded it to github. Looking at the code, I can see my horrible C style of the time. There's probably bugs galore.

      https://github.com/JetSetIlly/Direwall

      If I remember correctly, it runs as a commodity and patches the socket library. Interestingly, the socket library was not re-entrant (unusual for Amiga libraries) so I had to patch the Exec OpenLibrary() function to monitor the loading of new copies of the socket library. But it's been a long time so memories are hazy.

      It'll be interesting to see if it is still compiles and runs for modern AmigaOS, if any active Amiga programmers are around to see.

    • alex0com 6 hours ago
      This reminded me of running Kerio Personal Firewall. When Kerio ended I switched to either ZA or Comodo firewall, one of them introduced a neat feature of running executables in containers. Made clicking random things so much easier. But the best part with all of these was restricting windows to where it could barely do anything. "RandomXYZ.DLL wants to execute random what and connect to random where? I dont think so MS." lol
    • Scrounger 3 hours ago
      Who remembers BlackICE Defender tho?

      https://archive.org/details/BlackICE_Defender

      • SV_BubbleTime 3 hours ago
        I was there for SoftICE and BlackICE.

        Simpler times.

    • brandon272 6 hours ago
      Completely forgot about ZoneAlarm. I remember using it in the early 2000s!
      • leokennis 1 hour ago
        I read ZoneAlarm and it was like suddenly a part of my brain that went unvisited for 25 years lit up...
      • Foobar8568 2 hours ago
        Same... Totally forgot about ZA.
      • nurettin 3 hours ago
        Such nostalgia! I probably forgot about it after switching over to Linux 25 years ago.
      • loeber 4 hours ago
        Same!
    • orangesilk 1 hour ago
      > [ZoneAlarm] I always found it weird that Linux never really had anything like it.

      There was simply no need for it. GNU provided most of the software, spyware was unknown.

      Only since comercial vendors package for linux and bring their spyware along, the desire to inspect network rose.

      • justsid 58 minutes ago
        This is such a naive view on computer security. It’s not just about spyware, which is also not exclusive to commercial vendors.
        • fsflover 54 minutes ago
          What else is this about? Debian repositories still contain no malware and if you install software exclusively from them, you'll be safe.
          • M95D 45 minutes ago
            Does it contain Firefox? How about Chrome?

            Quote from LittleSnitch:

            > Little Snitch for Linux is built for privacy, not security

            What's your definion of malware in this context?

            • fsflover 1 minute ago
              It contains Firefox and Chromium. You are right that they may call home, but at least it's very limited and easily configurable. Could be too much for you but fine with me. Also Debian does change their config by default to minimize privacy issues.
    • avazhi 2 hours ago
      Back in the Halo 2 days ZoneAlarm and Cain and Abel were the go-to host bridging and bluescreen programs.

      A simpler time lol.

      Used to use Outpost Firewall Pro, too.

      • Chaosvex 2 hours ago
        Good old Halo 2 stand-bying. An absolute plague.
    • VerTiGo_Etrex 4 hours ago
      Wow. Insane throwback. I think I first learned about ZoneAlarm from some PC magazine my parents bought for me. Completely forgot about this great piece of freemium!
      • asimovDev 2 hours ago
        if anyone else suddenly started wondering, PC magazines still exist in physical form. There are even still Linux magazines that come with installer CDs for distros. And all kinds of other magazines as well, like for Mac computers, for photo editors, for Raspberry Pi etc.
      • whalesalad 3 hours ago
        I learned about it from Leo and Patrick on The Screen Savers
    • latentpot 46 minutes ago
      It was problematic, so we moved to blackice defender iirc
    • jerukmangga 6 hours ago
      It's interesting hw lng it took for linux to get a user friendly application firewall like OpenSnitch
      • M95D 42 minutes ago
        It's because there's no way to make universal kernel modules/drivers, like it is on Windows.
    • kasperset 4 hours ago
      There was also Tiny Firewall which got bought by Computer Associates around 2005. Probably the most complicated or fine grain control for me at that time in Windows XP.
      • distances 2 hours ago
        This is what I used! At some point I managed to block DHCP lease renewals on my computer, and Internet would always stop working after a given timespan. Took a good while to figure out I caused the problem myself.
        • vasvir 1 hour ago
          and that's how you learn...

          Shooting yourself in the foot really helps to built intuition!

          • Zobat 13 minutes ago
            Sometimes called "high instructional value".
    • DerSaidin 1 hour ago
      For me it was Sygate personal firewall back on windows xp
    • pachouli-please 4 hours ago
      i loved zonealarm! and also pained myself with all the little rules and upkeep lol
    • laweijfmvo 6 hours ago
      isn’t this essentially built into Windows these days? although it seems to come with a lot of programs pre-approved.
      • wolrah 5 hours ago
        No, the Windows firewall in its default configuration does not restrict outbound connections in any way. Any application can make any outbound connection it wants. If an application attempts to listen for incoming connections from external sources and there is not an existing policy, Windows will pop up a dialog asking the user if they want to allow this and if so whether it should be allowed to listen on all networks, only networks marked as "private", or for domain-bound corporate computers only networks where the domain controller is reachable.

        It can be manually configured with very detailed policies, but you have to know where to go to find those controls.

        It's been a while since I used ZoneAlarm or Little Snitch, but the last time I used either one the default behavior was instead that any connection attempt or attempt to listen for which there was not a policy would result in a dialog showing all the details about what application is looking to connect to or receive connections from what as well as a variety of options for creating a policy or even not creating a policy and just deciding whether that one connection would be allowed.

        Also back when I used ZoneAlarm I had dialup so the taskbar addon they had which showed realtime bandwidth usage and what applications had active connections was really useful. It also had a big red "Stop" button that would immediately disable all connections, which thinking about it in retrospect really makes me miss the more innocent days of the internet.

      • BoredPositron 6 hours ago
        Most of the windows firewalls tools are just front ends for the integrated one with more sensible defaults.
    • poglet 7 hours ago
      [flagged]
      • weird-eye-issue 6 hours ago
        That website redirected my browser to a very sketchy website after a couple seconds.

        Don't open it.

        @dang

        • armadyl 6 hours ago
          That domain is blocked by Hagezi's Ultimate list. Definitely remove that user's comment
        • cwillu 6 hours ago
          @dang doesn't do anything; send a quick email to the contact address with a link
  • cromka 1 hour ago
    I know it sounds crazy at this point, but with popular YouTubers switching to Linux, gamers overall well-aware of Steam on Linux advantages and switching as well, plus popular software like LittleSnitch getting ported, 2026 can without irony be named as Year of Linux Desktop, right?
    • Perz1val 0 minutes ago
      Also unrelated, but more linux gamers proves my personal observation that on the spectrum of computer literacy gamers are just below powerusers and programmers. We see more less technical people migrate over to Linux gradually and now it's gamers turn. Well, that's kind of obvious for everybody except Microsoft apparently.
    • dainank 56 minutes ago
      I think there is a lot of talk (and this is good), but very little action. Market share is still incredibly low for LNX. I believe only a small subset of people actually attempt the jump from WIN to LNX (since most just want to play their games and run their programs without hassle) and then quickly realize that its tougher than they anticipated and swiftly return to WIN.
      • Doxin 29 minutes ago
        5% on the steam survey though. The jump isn't quite as big from previous years as it seems as they did some corrections to the statistics this year, but 5% is nothing to sneeze at.
    • IshKebab 24 minutes ago
      No.
  • supernes 1 hour ago
    Tried it on Fedora 43 (6.19.11 x86_64) and it loaded all CPU cores, dumped 50K lines in the journal and failed to start.

    > Error: the BPF_PROG_LOAD syscall returned Argument list too long (os error 7).

    > littlesnitch.service: Consumed 3min 38.832s CPU time, 13.7G memory peak.

  • Bromeo 7 hours ago
    How does it compare to opensnitch? https://github.com/evilsocket/opensnitch
    • sgc 4 hours ago
      I just tried littlesnitch and it did not resolve very many ips to domains, which is pretty basic. It also failed to identify most processes, and they were grouped under "Not Identified". It appears these are known limitations of the Linux version [1]. So for that alone I need to stick with opensnitch.

      [1] "Little Snitch for Linux is built for privacy, not security, and that distinction matters. The macOS version can make stronger guarantees because it can have more complexity. On Linux, the foundation is eBPF, which is powerful but bounded: it has strict limits on storage size and program complexity. Under heavy traffic, cache tables can overflow, which makes it impossible to reliably tie every network packet to a process or a DNS name. And reconstructing which hostname was originally looked up for a given IP address requires heuristics rather than certainty. The macOS version uses deep packet inspection to do this more reliably. That's not an option here." -- from https://obdev.at/products/littlesnitch-linux/index.html

      • toredash 2 hours ago
        Is there any DNS based software to do block/allow? Kinda lika what's present in CiliumNetworkPolicies in Kubernetes networking?
        • gus_ 8 minutes ago
          OpenSnitch (+ block lists) ;)

          or DNS stubs with filtering capabilities.

        • M95D 38 minutes ago
          Yes, PiHole is the most common, but malware can easily bypass that using shared domains, P2P or IP addresses directly.

          Use a filtering proxy instead and no gateway / route to the internet.

        • Milpotel 2 hours ago
          You mean like PiHole or AdGuard?
    • lapcat 7 hours ago
      "I researched a bit, found OpenSnitch, several command line tools, and various security systems built for servers. None of these gave me what I wanted: see which process is making which connections, and in the best case deny with a single click." https://obdev.at/blog/little-snitch-for-linux/
      • haswell 7 hours ago
        I've used OpenSnitch for years, and while LittleSnitch definitely has a better UI for showing which process is making which connections over time, OpenSnitch does a pretty good job here. I get a modal popup when a program that hasn't made a connection tries to make a connection, and I can either allow/deny in one click, or further customize the rule e.g. allowing ntpd to connect, but only to pool.ntp.org on port 123.

        Where LittleSnitch is definitely ahead is showing process connections over time after said process has been allowed.

        • unsnap_biceps 5 hours ago
          When I looked at OpenSnitch (years ago), it didn't support running headless on a server. Am I mistaken about this, or has it changed?
          • sgc 4 hours ago
            You can run daemons on several nodes (different machines) and view them all through a central ui, it is pretty cool.
          • mixmastamyk 5 hours ago
            The UI is a separate package. Though you might just configure the firewall yourself at that point.
    • colesantiago 6 hours ago
      It is free, no subscription at all and truly open source.

      As software should be.

      • lordmoma 6 hours ago
        how should maintainer make money?
        • abeyer 4 hours ago
          Personally I'd be fine with a commercial license with source available here... the issue isn't the price, it's the fact that you're asked to MITM every network connection you make under the control of a binary blob.

          I think it's fair to ask that a developer choosing to build a thing that requires that kind of access should be expected to err on the side of transparency.

        • righthand 2 hours ago
          • konart 56 minutes ago
            So... what if the maker can't make it on donations only?
        • foo12bar 5 hours ago
          Hunt, gather.
          • SV_BubbleTime 3 hours ago
            There was also toolmaker to support the hunter and gatherer… so… back to square one.
  • mathfailure 6 hours ago
    Nice to have this as an extra option, but being a linux user I value openness of code. I am pretty content with opensnitch + opensnitch-ui.
  • riobard 48 minutes ago
    >> The macOS version uses deep packet inspection to do this more reliably. That's not an option here.

    I thought it would be easier to do DPI on Linux than macOS. No???

    • amonith 2 minutes ago
      Yeah I thought that was one of the primary use cases of eBPF. Not an expert though, just read about some of these things.
  • dSebastien 1 hour ago
    I've been using Simplewall on Windows for a while but I think it's not maintained anymore. Need to find an alternative
    • high_priest 1 hour ago
      Fort Firewall is my tool of choice. Each connection requires explicit approval.
      • efilife 41 minutes ago
        same with simplewall
  • Cider9986 6 hours ago
    This has the author's blog post on it https://obdev.at/blog/little-snitch-for-linux/
  • tankenmate 2 hours ago
    I'm so surprised that so few people have heard of Portmaster, it's been around for years and runs on Linux (and Windows if you must). And if you don't need traffic history it's free.
    • cyberpunk 2 hours ago
      portmaster is the tool i use for upgrading installed ports on freebsd since… like… olden times.
  • hubabuba44 1 hour ago
    Congrats on the Linux port, this looks very nice.

    Shameless plug: for anyone who wants something fully open source and terminal-based, I maintain RustNet (https://github.com/domcyrus/rustnet). It's a bit different because it's a TUI for real-time connection monitoring with deep packet inspection, not a firewall. No blocking/rules, but it's cross-platform (Linux/macOS/Windows), the entire codebase is open, and it sandboxes itself after init via Landlock with capability dropping.

  • parhamn 5 hours ago
    Okay hear me out, I use little snitch for a while. Great product. Love finding out what phones where. I make every single request (except my browser, because I'm fine with their sandbox) block until I approve.

    Recently I was wondering how you really have to trust something like little snitch given its a full kernel extension effectively able to MITM your whole network stack.

    So I went digging (and asked some agents to deep research), and I couldn't find much interesting about the company or its leadership at all.

    All a long way to say, anyone know anything about this company?

    • ignoramous 1 hour ago
      disclaimer: I co-develop (FOSS) Little Snitch / Open Snitch inspired firewall but for Android

      > little snitch given its a full kernel extension

      On macOS, don't think Little Snitch needs kernel exclaves / extensions. Apple provides userspace ("Network Extension") APIs (however limited) for apps like Little Snitch to use (instead of pf).

      > effectively able to MITM your whole network stack

      "MITM" means something else, anywho... if network observability (not firewall) is the primary need, cross-platform (GUI) sniffers like Sniffnet exist: https://github.com/GyulyVGC/sniffnet

    • lapcat 5 hours ago
      > All a long way to say, anyone know anything about this company?

      Yes, they are indie Mac developers who have been in business for more than 20 years, and Little Snitch for Mac is beloved by many users for a long time.

      • umpalumpaaa 5 hours ago
        Everything has a price though… (I also use little snitch)
        • lapcat 5 hours ago
          > Everything has a price though…

          What is that supposed to mean in this context?

          • gmzamz 4 hours ago
            Given sufficient motivation the little snitch dev could essentially supply chain attack every user, or even specific users.

            Said motivation could be a nation state handing them $XXX million dollars

            • parhamn 4 hours ago
              Or even sell the whole org for say $50M and no one ever mentions anything.

              I think the type of users it attracts (techies, crypto ppl, etc) makes it worth more too.

              • lapcat 4 hours ago
                > I think the type of users it attracts (techies, crypto ppl, etc) makes it worth more too.

                No, this by itself doesn't make Little Snitch or any business worth $50M. You're dreaming. That's a crazy valuation.

                • scheme271 4 hours ago
                  Various intelligence agencies are willing to pay 2-3M for a working exploit for iphone or android. I think that they would be fine with paying 50M for a userbase that has a high population of devs, admins, etc. Being able to backdoor someone like this in the right organization down the line is probably worth 50M.
            • umpalumpaaa 4 hours ago
              That’s what i meant. Thanks for reading my mind. :)
            • lapcat 4 hours ago
              > Said motivation could be a nation state handing them $XXX million dollars

              You're missing the most important part of the motivation here: why in the world would a nation-state give a damn about Little Snitch, especially to the tune of $XXX million dollars?

              A nation-state could pay $XXX million to your significant other to spy on you. But again, a nation-state doesn't give a damn about you.

              • wafflemaker 4 hours ago
                >why in the world would a nation-state give a damn about Little Snitch, especially to the tune of $XXX million dollars?

                Per user hacked, it can be very cheap¹ compared to bribing anyone. And give data/access that SO can't get.

                State is not interested in you until it does. Being Jewish, Polish, Gypsy, Gay. Or just WrongThinking. Or maybe it becomes super cheap and easy to process all information?

                1: it can even be free. You either give us backdoor to all your users or you rot in jail. Here's a complementary beating up or pictures of your kids, to argument our position further.

                • selcuka 1 hour ago
                  > it can even be free. You either give us backdoor to all your users or you rot in jail.

                  It is already a thing, at least in UK and AU [1]:

                  > Both countries now claim the right to secretly compel tech companies and individual technologists, including network administrators, sysadmins, and open source developers – to re-engineer software and hardware under their control, so that it can be used to spy on their users. Engineers can be penalized for refusing to comply with fines and prison; in Australia, even counseling a technologist to oppose these orders is a crime.

                  [1] https://www.eff.org/deeplinks/2018/12/new-fight-online-priva...

              • chabreck 4 hours ago
                its been known for some time that little snitch and other personal firewalls are established targets of three-letter agencies https://news.ycombinator.com/item?id=13813160
          • Leptonmaniac 3 hours ago
            Well, that is obvious, is it not? It means They are interested in The Plan and have enough power that a vague comment is all you gonna get. Cannot have Them finding out that we are on to Them. Though of course, The Plan already accounts for that, so They already know and will do Something about it. Want facts? Wake up, do your Research!
  • microtonal 1 hour ago
    Wow. I have used Little Snitch on Mac for years, love this!

    If anyone from obdev is reading, please give us a way to pay for it, even if it stays free :), I'd love to support development and would happily pay something between the price of Little Snitch and Little Snitch Mini.

    Anyway, thanks a lot!

  • Avicebron 7 hours ago
    Probably should throw it out there that I'm building something inspired by littleSnitch for windows. Currently a bit stealthy about it. But when I crowd source the funding for a code signing cert I'll get it out there. Lots of inspiration from LittleSnitch, in spirit if not actual code.
    • forsalebypwner 6 hours ago
      I'd be curious to hear additional details if you can share - got a timeline, or somewhere I can enter my email address for updates? I'd love to alpha/beta test if you're looking for testers.

      I've been a GlassWire user for years, which partially fills the role of LS, but not very well. Aside from the many performance issues I've seen, it's missing a lot of LS essentials. To be fair, I think the focus of GlassWire is more about visualizing traffic on your Windows computer, but I definitely believe there is a need for better Windows network software for power users.

      • Avicebron 5 hours ago
        It's a custom WFP driver. No timeline yet..

        If you or I guess anyone is curious sereno[hyphen]alpha[dot]ramble[thenumberoftechn9ne'sfavoriterum]@passinbox.com

  • xrio 1 hour ago
    Back when I was still using macOS I loved Little Snitch and was a paying customer. And I agree nothing on Linux comes close. Would it be technically feasible to also provide this as a Flatpak to support immutable distros like Bazzite?
  • TheTaytay 4 hours ago
    I’ve been researching the “best” way to build a little outbound network proxy to replace credential placeholders with the real secrets. Since this is designed to secure agents workloads, I figured I might as well add some domain blocking, and other outbound network controls, so I’ve been looking for Little-snitch-like apps to build on. I’ve been surprised to find that there aren’t a ton of open source “filter and potentially block all outbound connections according to rules”. This seems like the sort of thing that would be in a lot of Linux admins’ toolkit, but I guess not! I appreciate these guys building and releasing this.
    • LoganDark 4 hours ago
      Something almost no firewalls get right is pausing connections (NOT rejecting them) until I've decided whether to allow or not. The only firewalls I've seen do this are Little Snitch for Mac, and Portmaster for Windows (before they made it adware / started locking existing local features behind the subscription).
      • tankenmate 2 hours ago
        I use Portmaster (on Linux) and I have never seen ads (either in the app or apps that get their DNS from Portmaster) on it. About the only thing I saw different between the free version and the base level paid for version was traffic history and weekly reports (and badges on Discord if that's your kind of thing).
      • Avicebron 4 hours ago
        Firewalls don't do this because they are built at the wrong layer to do proper pending calls. It's too narrow of a design space for most firewalls to care.
        • LoganDark 4 hours ago
          True, most firewalls aren't built to pause for user input. But then again, that's why almost no firewall software is suitable for this user experience.
  • mostlysimilar 6 hours ago
    Incredible. LittleSnitch is must-have for macOS and trying to get equivalent functionality on Linux was painful. So very happy to see this, and very happy to give the developers at Objective Development my money.
    • mayama 3 hours ago
      In linux, I trust most distro apps to run with network access without any sort of firewall. And for apps from internet, just put them in bubblewrap or run with flatpak without access to homedir, network, audio, video etc. depending on program.
    • pixxel 2 hours ago
      [dead]
  • hackingonempty 7 hours ago
    LittleSnitch doesn't tattle on itself phoning home.
    • allthetime 2 hours ago
      It does… and if it didn’t it would be trivial to prove.
    • p-e-w 6 hours ago
      Is that true? If so, that’s not a good sign. I remember how impressed I was by ZoneAlarm in the early 2000s asking permission for itself to connect to the Internet, using the exact same dialogue it presented for any other program, with no dark patterns suggesting that the user should give preferential treatment to it.
      • jshier 6 hours ago
        Doesn't seem to be, I can see LittleSnitch itself connecting to yoyo.org and obdev.at. GP may be referencing a past bug, either in LittleSnitch or macOS.
  • wolvoleo 2 hours ago
    Ohhh interesting. Little snitch is one of 2 apps I miss from when the Mac was my daily driver. The other app was pixelmator
  • adrianwaj 3 hours ago
    There was a similar Show HN from 3 weeks ago. https://news.ycombinator.com/item?id=47387443 (open source too) - and there is a live window from all the machines in the swarm. https://dialtoneapp.com/explore - but only 2 so far. Maybe LittleSnitch can generate more data than this? Could end up an immune system for bad actors.

    Anything new to get much better performance from low-spec machines that is idiot-proof is a game-changer.

  • eviks 3 hours ago
    Does it leak your IP like the Mac version?

    https://news.ycombinator.com/item?id=35363343

    > Little Snitch for Linux is not a security tool.

    Maybe not?

    > Its focus is privacy:

    Or maybe yes?

  • xn--yt9h 1 hour ago
    Giving it a shot right now. Very easy setup, intuitive UI, but a lot of requests' processes are not identified (while they could easily be identified, as they belong to the browser that has some, but less, identified calls)
  • cromka 58 minutes ago
    I'd like to point out it uses very little memory, barely 33MB here. That's impressive!
  • winrid 3 hours ago
    Related - I'm working on launching Watch.ly[0] (human-in-the-loop for remotely approving network and file system access for agents) in the next week or so. It works similarly, via eBPF (although we can also fall back to NFQUEUE). Supporting 5.x+ linux kernels[1], osx, and windows.

    Did not know about LittleSnitch, will definitely check it out.

    [0] https://watch.ly/

    [1] https://app.watch.ly/status/

  • Tepix 1 hour ago
    > One thing to be aware of: the .lsrules format from Little Snitch on macOS is not compatible with the Linux version.

    Why?

    • cromka 1 hour ago
      Probably because it relies on eBPF rules on Linux?
  • alsetmusic 5 hours ago
    Congrats to Linux users on getting a great tool from a quality development shop. Objective Development is one of our (Mac users) exemplars for attention to detail and fit & finish.

    Congrats to Objective Development for expanding their well-loved tool to a new platform. You guys rock.

    • ProllyInfamous 5 hours ago
      >attention to detail

      Why does LittleSnitch (Mac) pre-resolve IP addresses, before user presses Accept/Deny?

      IMHO DNS queries shouldn't initiate without user input.

      • alsetmusic 3 hours ago
        Question for devs, not me.
        • eviks 2 hours ago
          Did the "attention to detail" phrase come from devs or you?
  • 0xbadcafebee 3 hours ago
    > Compatible with Linux kernel 6.12 or higher

    I know everyone today is used to upgrading every 5 seconds, but some of us are stuck on old software. For example, my Linux machine keeps rebooting and sucks up power in suspend mode because of buggy drivers in 6.12+, so I'm stuck on 6.8. (which is extra annoying because I bought this laptop for its Linux hardware support...)

  • sersi 1 hour ago
    > For keeping tabs on what your software is up to and blocking legitimate software from phoning home, Little Snitch for Linux works well. For hardening a system against a determined adversary, it's not the right tool.

    What would be the right tool to harden in a similar way to little snitch on mac? Meaning intercepting any connection and whitelisting them reliably.

  • mrbluecoat 5 hours ago
    > The macOS version uses deep packet inspection to do this more reliably. That's not an option here.

    Isn't MacOS just *nix under the hood? Genuinely curious about this difference.

    • firelizzard 3 hours ago
      An operating system is roughly broken into three parts: the kernel, the core system tools, and the shell (the desktop environment and/or the CLI shell). Linux: Linux kernel, GNU coreutils (usually), KDE/Gnome/etc + CLI shells. macOS: XNU, BSD userland + launchd/etc, Aqua/Cocoa. Windows: NT kernel, Win32/WinRT/etc, Windows Shell.

      The systems LittleSnitch uses to do packet inspection are very much OS-specific. There's no generic standard for doing high-performance packet inspection. XNU and Linux are *very* different kernels. Linus Torvalds built Linux from scratch as a monolithic kernel because he wanted a Unix-like OS that wasn't encumbered. XNU is based on the Mach microkernel though XNU is a hybrid or monolithic kernel, not a microkernel. The point is, they have very different heritage and very different systems for... well pretty much everything. So "just *nix under the hood" is kind of true but also completely besides the point as far as packet inspection goes. And even then, while there are a lot of similarities between the core system tools of Linux and macOS, they're still quite different and unless you're limiting yourself to POSIX-standard interfaces (which are only a fraction of the system), you're not going to be able to use the same code on both systems.

    • manwe150 5 hours ago
      More the opposite. macOS is a veneer of nix, but underneath it is the XNU microkernel. Lots more nuance since Apple took over and added a lot of their own performance and API improvements to
    • ekropotin 5 hours ago
      From what I understand, macOS uses weird kernel implementation, which is almost open source, but not 100%
      • firelizzard 3 hours ago
        You're correct, but for a bit more context: The macOS kernel is XNU, which is derived from/based on the Mach kernel, but heavily modified. The kernel itself is open source but some drivers/kernel extensions are not so it's not actually usable (unless you provide your own implementations of those).
    • gnerd00 5 hours ago
      BSD family with fewer GPL parts each year
  • badc0ffee 5 hours ago
    Does anyone know how the blocking functionality works? I worked on some eBPF code a few years ago (when BTF/CO-RE was new), and while it was powerful, you couldn't just write to memory, or make function calls in the kernel.

    Is there a userland component that's using something like iptables? (Can iptables block traffic originating from/destined to a specific process nowadays?)

  • Dig1t 6 hours ago
    >The daemon (littlesnitch --daemon) is proprietary, but free to use and redistribute.

    Worth noting that it is closed source. Would be worth contributing patches to OpenSnitch to bring it up to parity with Little Snitch.

    https://github.com/evilsocket/opensnitch

  • txrx0000 5 hours ago
    As articulated in the author's own blog post:

    https://obdev.at/blog/little-snitch-for-linux/

    The core issue is simple and uncomfortable: through automatic updates, a vendor can run any code, with any privileges, on your machine, at any time.

    -----

    If the author is serious about this, then they should make their own program completely open source, and make builds bit-for-bit reproducible.

    For all I know, the proprietary Little Snitch daemon, or even the binaries they're distributing for the open source components, contain backdoors that can be remotely activated to run any code, with any privileges, on your machine, at any time.

  • shevy-java 30 minutes ago
    The ultimate turnaround would be if the little snitch is snitching on the user too.
  • flexagoon 5 hours ago
    Also see Safing Port master:

    https://safing.io/

  • wodenokoto 1 hour ago
    Honestly I think it is odd such a tool isnøt considered as standard to an OS as a process manager.

    Anyway, this one looks great. I hope Linux distros will incorporate this or similar into the network widgets.

  • SamuelAdams 7 hours ago
    So if this is free to use on linux, what is to stop someone from doing what Colima did to Docker? Aka make a tiny Linux VM on MacOS and package Little Snitch within that?
    • Cider9986 7 hours ago
      It barely has any of the features of the MacOS version, there is no shortage of cracks for Little Snitch, and there is Lulu. Other than that, I am not sure.
    • azinman2 7 hours ago
      I don't think it'll have access to the macOS connections, and certainly cannot act at the kernel-supported level as a firewall on the Mac side.
    • firelizzard 3 hours ago
      Little Snitch requires packet inspection. If you ran it in a Linux VM, it will inspect packets within the VM. So... kind of useless for monitoring connections on the host.
  • akimbostrawman 44 minutes ago
    i will never understand why people will flock to this but opensnitch which is just better, fully open and has existed for longer (on linux) gets ignored.
    • RamblingCTO 31 minutes ago
      then it pretty obviously is not better?
  • FloatArtifact 6 hours ago
    I wish applications like this could coordinate with upstream firewall like opnsense
  • imagetic 2 hours ago
    Dope.
  • rvz 7 hours ago
    Also from [0].

    > You can find Little Snitch for Linux here. It is free, and it will stay that way.

    Don't worry, the authors know that there's no point in charging Linux users. Unlike Mac users.

    So you might as well make it $0 and the (Linux) crowd goes wild that they don't need to pay a cent.

    However...

    > I researched a bit, found OpenSnitch, several command line tools, and various security systems built for servers. None of these gave me what I wanted: see which process is making which connections, and in the best case deny with a single click.

    OpenSnitch is open source. You don't need to trust it as you can see the code yourself. Little Snitch on the other hand, is completely closed source.

    Do you still trust them not to do self-reporting or phoning home, even though it is $0 and closed source?

    [0] https://obdev.at/blog/little-snitch-for-linux/

    • papascrubs 6 hours ago
      Two of the three components of LittleSnitch for Linux are open source. The eBPF (kernel portion) and UI are fully open source.
    • lapcat 7 hours ago
      > Do you still trust them not to do self-reporting or phoning home, even though it is $0 and closed source?

      If you trust Little Snitch on Mac, then yes.

      They've been in business for over 20 years. They're not going to blow their entire business and reputation for a few Linux users.

      • emmelaich 6 hours ago
        Yep, I trust the obdev.at / Snitch guys.

        I do wonder however, are they sufficiently careful about their processes and own machines to avoid a supply chain attack completely.

        They must be a target for the various hacking groups out there.

        • lapcat 6 hours ago
          This comment seems a bit confused.

          A supply chain attack doesn't directly attack an end developer but rather a supplier of the developer. So who or what is the supplier in this case?

          • emmelaich 5 hours ago
            They don't build their own machines or write their compilers or write their own crpyto code or ... so many other things.
            • lapcat 5 hours ago
              > They don't build their own machines or write their compilers or write their own crpyto code or ... so many other things.

              An attack on any of these things has nothing specifically to do with the developers of Little Snitch and would have vastly more widespread and important effects.

              Why would you even be talking about Little Snitch if a compiler were compromised?!? Your paranoia here is bizarrely narrow. Little Snitch would be the least of our problems in that case.

              • emmelaich 3 hours ago
                Their copy of the compiler. Just an example. ¯\_(ツ)_/¯
          • LamaOfRuin 5 hours ago
            That seems... not correct?

            The comment was asking about preventing a compromised supplier for the developers.

            A supply chain attack can be anywhere in the supply chain to the target. If I, the end user, am the target, then a supply chain attack compromising the developer of LittleSnitch is effective.

            I may then be a conduit to compromising other software or components, and would both I and LittleSnitch would be part of the supply chain that could be attacked targeting them.

            • lapcat 5 hours ago
              > If I, the end user, am the target

              You're not a target, anonymous rando.

              • microtonal 1 hour ago
                Many supply chain attacks aim to run malware on the end-users machine to harvest authentication tokens, etc. So pretty much everyone here who is a developer is the target.
          • hsbauauvhabzb 6 hours ago
            This seems pedantic and I think you know what they’re questioning and why.
            • BoredPositron 6 hours ago
              If they trust the devs why would they not trust them to not yolo deploy new versions?
              • dylan604 6 hours ago
                because a company worthy of trust doesn't yolo their versions. a company that does yolo versions is not trustworthy.
              • hsbauauvhabzb 5 hours ago
                Because it might not be the developers doing the deploying, but a malicious actor?
            • lapcat 6 hours ago
              > I think you know what they’re questioning and why.

              No, not really. And I disagree with the premise, "They must be a target for the various hacking groups out there."

              How would you even hack them? I'm a developer too; how would you hack me?

              • heartbreak 6 hours ago
                Options range from carefully targeted phishing or social engineering attacks to poor opsec and a five dollar wrench.
                • lapcat 5 hours ago
                  > a five dollar wrench.

                  I'm not even going to respond to this ridiculousness.

                  I still don't know why anyone thinks that, among all developers in the world, a little indie Mac developer is getting targeted specifically.

                  • emmelaich 3 hours ago
                    Some targets are more valuable than others. A firewall product has obvious security value. The fact that it requires high privilege is another reason.

                    I have the same thoughts about other Mac apps. e.g. iTerm2 - cause they "see" so much sensitive data.

              • emmelaich 5 hours ago
                ?! The same way every other developer that has been hacked. You surely cannot be suggesting you're un-hackable. That seems ludicrously hubristic.
                • lapcat 5 hours ago
                  > The same way every other developer that has been hacked.

                  There's not one single way, so, no, you're just hand-waving here.

                  • emmelaich 3 hours ago
                    Just saying developers have been hacked. Underrated existence proof.
  • clomia 1 hour ago
    good
  • chris_wot 4 hours ago
    Can someone elaborate on the limitations bit?

    "Little Snitch for Linux is built for privacy, not security, and that distinction matters. The macOS version can make stronger guarantees because it can have more complexity. On Linux, the foundation is eBPF, which is powerful but bounded: it has strict limits on storage size and program complexity. Under heavy traffic, cache tables can overflow, which makes it impossible to reliably tie every network packet to a process or a DNS name. And reconstructing which hostname was originally looked up for a given IP address requires heuristics rather than certainty. The macOS version uses deep packet inspection to do this more reliably. That's not an option here."

    Is this a limitation of the eBPF implementation? Pardon my ignorance, I'm genuinely curious about this.

  • computing 4 hours ago
    doesn't work on arch (btw)
  • LoganDark 4 hours ago
    Yess, the return of the actually good landing page for the technically-minded. Now all they need to do is roll back the macOS one that looks and reads like it was designed by a marketing agency that knows nothing about computers (or even Little Snitch itself).
  • waterTanuki 6 hours ago
    Why would one use this over PiHole?
    • JoeBOFH 6 hours ago
      This is different. This shows you what in your operating system is making connections out and to where.
    • roughly 6 hours ago
      I run both (LS on Mac, at least), they do different things - pi.hole is a great ad blocker which applies to all of the devices on your network. Little Snitch is doing something different - it tells you every call that every app you use is making, and allows you to approve or deny each one. So, you can block telemetry for apps, or you can block certain apps from contacting certain servers, or you can just use it to watch what apps on your system are calling out to where.
      • waterTanuki 5 hours ago
        To clarify, I'm aware that pihole is not intended to run on a client OS, and doesn't monitor at a process level. I'm focused on the intended effect rather than the process itself (blocking malicious/ad servers). And I think I framed my initial question incorrectly as if LS and PiHole as subtitutes. It's perfectly fine and even preferrable to use both as layered protection. I'm just thinking however when it comes for bang-for-buck it seems like PiHole is the better value proposition if you could only set up one.

        pi.hole is primarily billed as an ad blocker, but the fundamental way it works is by applying a curated set of DNS lists that are blocked (commonly telemetry and ad servers), and the admin dashboard which is just a web page (therefore works on all platforms, smartphones included) will do the same thing: it tells you every call that every app on every device on your network is making, and you can approve or deny it. You can curate your own list as well and block servers/connections you don't want on the network.

        LS afaik operates in the same area where it's intended to be used for privacy. I guess I could see it being useful for people who don't have admin access to their router, but for people who do have such access I would think the benefits of network-wide DNS monitoring/blocking would outweight the costs of having to configure your router settings.

        • LamaOfRuin 5 hours ago
          LS seems to not be claiming any security promise on Linux because it can't make any guarantees given eBPF limitations. But the entire purpose is different and there is very little overlap in my view. PiHole is entirely (I think?) just applying the blocklist made easy. LS allows you to build the blocklist in real time.

          I would guess that to the extent the blocklists include things that are loaded by applications and not websites, they are almost entirely built by users of something like LittleSnitch or OpenSnitch. This is also entirely doable with wireshark logs, but I think that requires more infrastructure to build into usable lists.

        • mixmastamyk 4 hours ago
          Some telemetry uses hardcoded addresses when DNS doesn't work.

          Some telemetry might not be recognized by pi-hole as it is new or has nothing to do with ads.

    • cortesoft 6 hours ago
      LittleSnitch isn't for ad blocking (only), it is for tracking/blocking/allowing ALL connections from various processes. PiHole only blocks DNS requests to known ad servers.
    • walrus01 6 hours ago
      Completely different thing. A littlesnitch type thing is for all traffic. Pihole is a DNS query thing that prevents various ad content from being loaded. It's also trivially easy for a malicious application with network access to bypass any instance of pihole on your LAN by doing its own DNS over HTTPS lookups to its own set of server(s) by IP.
      • waterTanuki 5 hours ago
        I mean, if you're at the point where your machine is compromised by a process with full network access little snitch won't help much either.
        • sampullman 5 hours ago
          You might be surprised, there are plenty of low effort attacks out there that just install a crypto miner and phone home periodically without doing much to cover it up.
  • gauravkashyap6 1 hour ago
    [dead]
  • VladVladikoff 5 hours ago
    Really like Lulu as an alternative to LittleSnitch https://objective-see.org/products/lulu.html
  • sneak 4 hours ago
    It’s not really necessary on Linux. Linux systems work without 40 invisible background services phoning home to the mothership to leak your hardware identifiers for FAA702 collection.
    • weikju 4 hours ago
      Linux maybe, not so true of all the DEs and apps installed on it
  • serious_angel 6 hours ago

      > The macOS version can make stronger guarantees because it can have more complexity. On Linux, the foundation is eBPF, which is powerful but bounded: it has strict limits on storage size and program complexity. Under heavy traffic, cache tables can overflow, which makes it impossible to reliably tie every network packet to a process or a DNS name.  
      > And reconstructing which hostname was originally looked up for a given IP address requires heuristics rather than certainty. The macOS version uses deep packet inspection to do this more reliably.  
      > That's not an option here.
      > 
      > Source: https://web.archive.org/web/20260409002901/https://obdev.at/products/littlesnitch-linux/index.html
    
    The above feels like an utter AI slop nonsense, sorry. I believe eBPF, the Linux Kernel feature, is absolutely capable for accuracy and perfect processing of network traffic.

    Have you ever checked Calico or Cilium, or at least, Oryx?

    • jiveturkey 6 hours ago
      I guess you haven't actually implemented anything in eBPF.
      • heatpump5n 4 hours ago
        Can you elaborate? I thought eBPF was created to be used in high performance scenarios, so I am confused why this shouldn't be posssible.
  • shawnta 2 hours ago
    Great website features, exactly what I needed, thank you.