SSH client

[khlsvr]

Describe the solution you'd like
I would like to experience ssh client on an ESP32 device. Perhaps better would be mosh with better resilience and less demanding, but since there already exists https://github.com/ewpa/LibSSH-ESP32 and https://github.com/hpirila/ESP32-Arduino-SSH maybe mosh is relevant if ssh gets done first? The idea has been mentioned elsewhere for example on PocketMage's github page ashtf8/PocketMage_PDA#11 but there's nothing to show for. PocketMage device has ESP32-S3 which has 512KB internal SRAM, which could be tight I guess, but now there are boards that have P4+C6 together etc. Could it be doable? This app would give so many use cases I think I don't need to even start. However I'm not sure whether you could write a generic all-arounder ssh client app to tactility OS given the specs of the ESP32 devices vary?

Describe alternatives you've considered
Raw TCP + Line-Oriented Command Protocol. Linux runs small command server (agent) and ESP32 talks to that. Run linux commands on ESP32, execute them at remote linux and get output back to ESP32. No TUI but for example you could still chat on IRC with e.g. ZNC by not attaching to it but by querying irc last 20 #linux and irc send #linux hello from esp32. This Raw TCP would be lighter and simpler than SSH but basic. Still useful.

[KenVanHoeylandt]

It should be feasible. At the very least it should be feasible when the device has PSRAM (SPIRAM) available.
If anyone feels like implementing this as an external app, they're welcome to do so.

It likely requires extending the list of exposed symbols.

[khlsvr]

SSH client would be a nice tool, but in the end it seems I might want something else a bit more in ES32-class hardware. I thought I add this comment here mainly for the arguments AI points out. If they have some merit they are good information. Are they? See them below.

My use case

I was talking to an AI and what it was saying about using an SSH client to things I had plans for was perhaps valid and it made me reconsider. Instead for my use case a request-oriented approach (short HTTPS requests to a helper server for IRC, email, feeds, or AI queries) would be better. It would align with my low-power and minimalist computing experiments goals. I have considered taking up on certain tech minimalism days in where I wouldn't be using any real operating system at all, but try manage with hardware on par 90s tech, like ESP32-class.

AI: Why an SSH client may be a poor fit for ESP32 in some use cases

This is not an objection in principle, but a note on practical constraints observed on ESP32-class hardware.

Key concerns:

• Memory pressure over long runtimes
  SSH combines TLS, crypto buffers, packet buffers, and terminal state. While each part is manageable alone, together they increase the risk of heap fragmentation and allocation failures after hours of uptime, especially during rekeying.

• Long-lived TCP sessions on Wi-Fi MCUs
  ESP32 Wi-Fi stacks are optimized for short, bursty traffic. Multi-hour interactive TCP sessions are more fragile and can stall or require Wi-Fi resets in marginal conditions.

• Rekeying as a failure point
  Periodic SSH rekeying temporarily spikes memory usage and is a common point where long-running embedded connections fail if the heap is fragmented.

• Terminal emulation complexity
  Interactive SSH requires ANSI parsing, scrollback, redraws, and state management, all of which are memory-hungry and difficult to tightly bound on an MCU.

• Hard failure model
  FreeRTOS is fine for networking and TLS, but lacks VM, overcommit, or OOM handling. When something goes wrong, the failure mode is a crash or reboot rather than graceful degradation.

SSH tends to work best on ESP32 when:

• sessions are short-lived
• terminal features are minimal
• reconnects are expected
• watchdog-based recovery is acceptable

For long-lived interactive sessions, the risk profile is significantly higher.

[d49406]

I like to see a SSH client in the future as an external app too, +1.
Totally get the utility, your use-case reminds me a bit of the SDF Public Access Unix System which is cool!
Having a pocketable SSH client for administrative tasks is also very neat.

Bruce has an SSH client in-built, maybe this could serve as a reference implementation? it is possible for sure.

I think security concerns are a bit moot to medium severity, given you only store password protected private keys or ideally, use keyboard auth.

[KenVanHoeylandt]

I'll always take security into account, but considering this is a tinkering platform and all apps have root access ... there is a limit to how far you can push this on an ESP32 anyway.

There's a library for separating system vs user space with an S3 (and maybe P4), but not all ESP32 hardware platforms support it, so it's not something I can implement at this point.

[NellowTCS]

+1 for SSH
I have an idea for the UI, let me design something rq

[NellowTCS]

something like this?

[NellowTCS]

Details

void onShow(AppContext& context, lv_obj_t* parent) {
  auto izygsrj7k = lv_obj_create(parent);
  lv_obj_set_pos(izygsrj7k, 5, 5);
  lv_obj_set_size(izygsrj7k, 790, 590);


  auto psoqj7fuh = lv_btn_create(parent);
  auto psoqj7fuh_label = lv_label_create(psoqj7fuh);
  lv_label_set_text(psoqj7fuh_label, "Send");
  lv_obj_center(psoqj7fuh_label);
  lv_obj_set_pos(psoqj7fuh, 685, 515);
  lv_obj_set_size(psoqj7fuh, 105, 40);

  auto p25n495f8 = lv_btn_create(parent);
  auto p25n495f8_label = lv_label_create(p25n495f8);
  lv_label_set_text(p25n495f8_label, "Tab");
  lv_obj_center(p25n495f8_label);
  lv_obj_set_pos(p25n495f8, 10, 485);
  lv_obj_set_size(p25n495f8, 80, 40);

  auto 0ams5bvwe = lv_btn_create(parent);
  auto 0ams5bvwe_label = lv_label_create(0ams5bvwe);
  lv_label_set_text(0ams5bvwe_label, "Ctrl");
  lv_obj_center(0ams5bvwe_label);
  lv_obj_set_pos(0ams5bvwe, 95, 485);
  lv_obj_set_size(0ams5bvwe, 80, 40);

  auto jwq3dxdlt = lv_btn_create(parent);
  auto jwq3dxdlt_label = lv_label_create(jwq3dxdlt);
  lv_label_set_text(jwq3dxdlt_label, "Alt");
  lv_obj_center(jwq3dxdlt_label);
  lv_obj_set_pos(jwq3dxdlt, 180, 485);
  lv_obj_set_size(jwq3dxdlt, 80, 40);

  auto 9d3xqqb4q = lv_obj_create(parent);
  lv_obj_set_pos(9d3xqqb4q, 10, 60);
  lv_obj_set_size(9d3xqqb4q, 780, 420);

  auto neh0jqxn4 = lv_label_create(parent);
  lv_label_set_text(neh0jqxn4, "SSH Client");
  lv_obj_set_pos(neh0jqxn4, 60, 25);
  lv_obj_set_size(neh0jqxn4, 100, 40);

  auto 908mh8u5g = lv_btn_create(parent);
  auto 908mh8u5g_label = lv_label_create(908mh8u5g);
  lv_label_set_text(908mh8u5g_label, "X");
  lv_obj_center(908mh8u5g_label);
  lv_obj_set_pos(908mh8u5g, 11, 14);
  lv_obj_set_size(908mh8u5g, 40, 40);

  auto k1ripeeq1 = lv_btn_create(parent);
  auto k1ripeeq1_label = lv_label_create(k1ripeeq1);
  lv_label_set_text(k1ripeeq1_label, "Esc");
  lv_obj_center(k1ripeeq1_label);
  lv_obj_set_pos(k1ripeeq1, 265, 485);
  lv_obj_set_size(k1ripeeq1, 80, 40);

  auto v8ql9wzug = lv_btn_create(parent);
  auto v8ql9wzug_label = lv_label_create(v8ql9wzug);
  lv_label_set_text(v8ql9wzug_label, "Connect");
  lv_obj_center(v8ql9wzug_label);
  lv_obj_set_pos(v8ql9wzug, 690, 15);
  lv_obj_set_size(v8ql9wzug, 100, 40);

  auto z5ka1iidl = lv_btn_create(parent);
  auto z5ka1iidl_label = lv_label_create(z5ka1iidl);
  lv_label_set_text(z5ka1iidl_label, "Home");
  lv_obj_center(z5ka1iidl_label);
  lv_obj_set_pos(z5ka1iidl, 350, 485);
  lv_obj_set_size(z5ka1iidl, 80, 40);

  auto 5un0pimj4 = lv_btn_create(parent);
  auto 5un0pimj4_label = lv_label_create(5un0pimj4);
  lv_label_set_text(5un0pimj4_label, "PgUp");
  lv_obj_center(5un0pimj4_label);
  lv_obj_set_pos(5un0pimj4, 530, 485);
  lv_obj_set_size(5un0pimj4, 70, 40);

  auto o6wcbb1jk = lv_btn_create(parent);
  auto o6wcbb1jk_label = lv_label_create(o6wcbb1jk);
  lv_label_set_text(o6wcbb1jk_label, "PgDn");
  lv_obj_center(o6wcbb1jk_label);
  lv_obj_set_pos(o6wcbb1jk, 605, 485);
  lv_obj_set_size(o6wcbb1jk, 70, 40);

  auto 8ui2wrnn7 = lv_btn_create(parent);
  auto 8ui2wrnn7_label = lv_label_create(8ui2wrnn7);
  lv_label_set_text(8ui2wrnn7_label, "Function");
  lv_obj_center(8ui2wrnn7_label);
  lv_obj_set_pos(8ui2wrnn7, 435, 485);
  lv_obj_set_size(8ui2wrnn7, 90, 40);

  auto ksh8h1slz = lv_label_create(parent);
  lv_label_set_text(ksh8h1slz, "");
  lv_obj_set_pos(ksh8h1slz, 300, 285);
  lv_obj_set_size(ksh8h1slz, 100, 40);

  auto qzvaj8694 = lv_obj_create(parent);
  lv_obj_set_pos(qzvaj8694, 255, 170);
  lv_obj_set_size(qzvaj8694, 300, 180);

  auto fogcjuea0 = lv_label_create(parent);
  lv_label_set_text(fogcjuea0, "Connect to a SSH Client");
  lv_obj_set_pos(fogcjuea0, 315, 190);
  lv_obj_set_size(fogcjuea0, 100, 40);
}

code (made using my thing, which is why it's not responsive)