TELNETLOGIN(8)

📦
version 0.17.41+0.2 · 3 versions
, in ubuntu jammy

💖 TELNETLOGIN 💖

okay so bestie, we're looking at telnetlogin from section 8 of the System Manager's Manual — that's the sysadmin-y corner of the manual, iykyk. she's a little login wrapper for telnetd and honestly she's got main character energy for such a tiny program. let's get into it 🎀

✨ NAME ✨

telnetlogin — login wrapper for telnetd

like, that's her whole job. she wraps. she logs you in. iconic behavior fr fr 💅

🦋 SYNOPSIS 🦋

telnetlogin [-h host] [-p] [-f username] [username]

look at that lil lineup of options. so cute. so specific. keep reading, it matters 😌

🌸 DESCRIPTION 🌸

so telnetlogin is a setuid wrapper that runs login(1). that's the whole vibe. she's meant to be invoked by telnetd(8), and the entire point of her existence — the idea, the dream — is to remove the necessity of running telnetd as root. no more running your network daemon as the all-powerful user, bestie. we're being responsible now 💖

here's the tea on how she's supposed to be set up:

  • telnetlogin should be installed mode 4750, user root, group telnetd.
  • then, telnetd may be run from /etc/inetd.conf as user nobody, group telnetd, and with the option -L path-to-telnetlogin.

see how that works? she takes the root privileges so telnetd doesn't have to. it's giving division of labor. it's giving least privilege. obsessed 😭

now, the options. telnetlogin accepts only the subset of options to login(1) shown above, and in the order listed. and listen — that order is not random, that's the order telnetd(8) normally provides them in. so don't get creative with it, bestie. she's not flexible like that 🚫

she also does sanity checks on the environment variables TERM and REMOTEHOST. yes, queen. she's checking your vibes before she lets you in. and she insists on two things:

  1. that the standard input, output, and error streams are open on a terminal, and
  2. that she is the process group leader of the foreground process of that terminal.

like she literally will not proceed otherwise. boundaries! we love a girl with boundaries 🫶

after checking all of these conditions, checking the values of the above environment variables for reasonable values, resetting signal handlers, and so forth — and yes, that "and so forth" is doing a lot of heavy lifting, but it's what the page says — she execs login. and that's it. that's the whole arc. she sets the stage and then becomes login. method acting. periodt 💅

👑 SEE ALSO 👑

the whole friend group. go read them too, bestie, they're connected 🌈

⚠️ RESTRICTIONS ⚠️

THIS IS PRESENTLY EXPERIMENTAL CODE; USE WITH CAUTION.

no cap. this is EXPERIMENTAL. the manual is literally yelling at you in all caps. please be careful, bestie, i am begging 🙈

📜 HISTORY 📜

telnetlogin was written during the development of NetKit 0.17. a lil origin story. a lil lore drop. love that for her ⭐

and that's a wrap!! this page comes to you courtesy of Linux NetKit (0.17) and it's dated April 12, 2000 — yes she's an elder millennial, no we don't hold it against her, she paved the way 🎀✨ bye bestie, stay setuid-safe!! 💖🦋💅

📦 where this page comes from