Unix v4 (1973) – Live Terminal

(unixv4.dev)

80 points | by pjmlp 2 hours ago

10 comments

  • Deeg9rie9usi 1 hour ago
    Reading the source unearths interesting things: https://sigma-star.at/blog/2025/12/unix-v4-buffer-overflow/
    • mananaysiempre 1 hour ago
      I kept expecting an exploit :) Something to poke at on a slow evening, I guess, though with the buffer in static memory it might be difficult.
      • Deeg9rie9usi 58 minutes ago
        Exploiting this is close to trivial because the adjacent buffer contains the pw entry. So, you can control what the input is compared with. That way the password check can be bypassed without injecting code.
        • mananaysiempre 11 minutes ago
          The crypt() of the input, not the input itself, but guessing at the (PDP-11 assembly :/ ) code for crypt() a bit, it seems to stop after 64 characters if it can’t find a null terminator before that, so

            0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef012345678901234567890123456789012345root:p3Y0ydAx:
          
          should work as an exploit, and indeed it does. (Arbitrary 64-character password, then 36 bytes to pad to the end of the 100-byte buffer, then the part of root’s /etc/passwd entry for said password until at least the second colon.)
  • Aperocky 12 minutes ago
    I wonder how hard is it to do the entire thing in browser/js. It seems hugged to death right now due to backend connections.
  • dim13 50 minutes ago
    Glad to have played with it a bit before it got Slashdotted. ;)
  • publicdebates 2 hours ago

        Session Error
        Rate limit exceeded: 10 per 1 minute
    • hnthrowaway0315 2 hours ago
      I managed to get in after a few tries. But then I got a timeout. I think I'm going to wait until the HN deathhug is over :D
  • ramon156 1 hour ago
    Rate limited! a new record!
    • yunnpp 29 minutes ago
      I'm going to guess we're on the same VPN.
  • enricotr 1 hour ago
    Almost slashdotted.
  • TZubiri 1 hour ago
    Getting a rate limit error, but I haven't used the program.
  • colesantiago 2 hours ago
    Just a heads up:

    > By using this service, you acknowledge that terminal sessions may be logged for educational and debugging purposes. No personal data is collected beyond your IP address.

    Is this all open source and is the code available? So that we know where the data is truly going?

    Hard to trust it if it isn't fully OSS.

    This is a cool demo though.

    • altairprime 1 hour ago
      > Hard to trust it

      Clarification requested: How is ‘trust’ applicable to this site?

    • voidfunc 2 hours ago
      Even if it was open source how do you know its not a fork?
      • lo_zamoyski 2 hours ago
        And even more to the point: this is a website. What is he afraid of this website doing that all the other websites don't already do? Why single this one out?
        • qarl 1 hour ago
          WARNING: YOU ARE ABOUT TO OPEN A WEBPAGE.
          • derrida 25 minutes ago
            Exception: -1 Page already opened. Time can only flow forward.
    • StableAlkyne 1 hour ago
      > Hard to trust it if it isn't fully OSS

      It's an emulated PDP-11, could you elaborate on the threat model here?

      I get that companies are being gross about logging everything online, but come on. It's okay to have fun.

      Who in their right mind is using this for anything other than curiosity's sake?

      • utopiah 1 hour ago
        Little bit of banking on an emulator on a random website, why not?
        • cocodill 1 hour ago
          bitcoin will not be mined on its own.
    • znpy 49 minutes ago
      Yeah it’s unlikely that this site will collect any meaningful data and it’s unlikely that you lose any meaningful data by playing with a virtual unix from the 70ies.

      You aren’t getting downvoted enough.

  • charcircuit 2 hours ago
    Did they get a license from Novell for this or is this as illegal as many of the other emulator sites with copyrighted software on them? Considering the page doesn't mention it, I'm leaning towards it being copyright infringement.
    • LukeShu 2 hours ago
      In 2002, Caldera licensed Research Unix <= 7th edition and 32-bit 32V Unix under a BSD-style license.

      Gotta stick the "This product includes software developed or owned by Caldera International, Inc." notice on it though.

      • charcircuit 1 hour ago
        This copy of Unix v4 came from AT&T and not one of the freely licensed ones Caldera released. Caldera may own the rights now for this unearthed copy, but I am not aware that they have provided licenses for this new release.
        • spijdar 40 minutes ago
          If your argument is that Caldera might not actually have the rights to UNIX in the first place to grant the license, that's fair.

          But the license they provided (http://www.lemis.com/grog/UNIX/ancient-source-all.pdf) explicitly names versions 1, 2, 3, 4, 5, 6, and 7 of UNIX for the 16-bit PDP-11. Yes, these versions originated at AT&T (Bell Labs) but are distinct legally from SysIII and SysV UNIX, also from AT&T, which are explicitly not covered by the Caldera license.

          • charcircuit 34 minutes ago
            Thank you for finding this.

            >Redistributions of source code and documentation must retain the above copyright notice

            The archived tape doesn't have this, which contradicts the license. This makes me think the license may only be referring to a set of source code that they released with this license text already applied as opposed to what was recently archived.

            >Redistributions in binary form must reproduce the above copyright notice

            I don't see the copyright notice on that page. So at the very least that may need to be added.

    • fortyseven 1 hour ago
      Personal financial stake in this, or do you regularly police the use of ancient software?
      • charcircuit 1 hour ago
        >Personal financial stake in this

        In the sense that the company I work for would be financially harmed if copyright infringement of software was freely allowed. I benefit from the ability of people being able to sell rights to use software.

        It's one thing to digitize and archive ancient software, it's another thing to allow people to freely use it without acquiring the proper license for it.

        • LastTrain 13 minutes ago
          I mean if you are assigning points I’d actually say the former is worse than the latter.
    • publicdebates 49 minutes ago
      What do you think about GOG?
      • yunnpp 26 minutes ago
        GOG is perfectly legal.
      • charcircuit 45 minutes ago
        It's good to have competition against Steam.