SSH client: a terminal on another machine (#2) #94

2026-10-08T02:38:57Z

twisla commented

2026-10-08 02:38:57 +00:00

Closes #2.

What it is

A new SSH App: one session to a shell on another machine, over libssh (ewpa/LibSSH-ESP32 5.10.0) on mbedTLS.

user@host[:port], typed in the App or as ssh user@host in the Shell. Up to eight hosts are remembered, once a login has succeeded.
Trust on first use, on the SHA-256 fingerprint. A changed key is a warning, with Cancel selected.
A password, typed each time and stored nowhere, or a key the device makes for itself (Ed25519): the public half is shown, written to /ssh/id_ed25519.pub and printed by ssh status.
A real terminal (lib/term, host-tested): enough for a shell, less, top, nano, vim. Sixteen colours, scroll regions, the alternate screen, 100 lines of scrollback.
Q257 as asked: Ctrl with + and - change the text size, five of them, from 60x20 to 26x8. The far end is told.
Leaving the App doesn't end the session. SSH shows in the Status Bar.

The decisions (Q254 to Q266), the measurements and every check are in docs/milestones/N1.md.

Three things beyond the App

Keys that aren't characters now carry Shift, Ctrl and Alt (key_mapper.cpp). The terminal needs it for Page Up and Alt+backtick. It also makes two documented keys work from the real keyboard that until now only worked from the Debug Console's key command: Ctrl+Fn+up/down in a note, Shift+Tab in Gemini.
IRC doesn't try to connect with less than 60 KB free. Started with a session open, its TLS handshake took the free heap down to 236 bytes, six times over. Now it says "not enough memory: close the SSH session" and waits.
A build script leaves libssh's own curve25519 out: libsodium (here for WireGuard) defines the same names.

What it costs


Flash	292 KB (the trial said 120: signing with the device's key links a 109 KB table). The firmware is at 71% of its slot
Heap, session open	about 50 KB of 99 KB
Lowest free heap during a login	30 KB
Not started under	75 KB free: not with IRC connected

Checked on the device

Against OpenSSH 9.7 in a container: first-time trust (fingerprint compared with the server's), password, ls, top, vim, the five sizes with stty size, scrollback, leaving and coming back, Ctrl+C, backtick, both ways of ending, key login ("Accepted publickey" in the server's log), a changed host key (Cancel and Replace), a wrong password, a closed port, bad targets, forgetting a host, IRC waiting while a session is open, memory back to 99 KB after. 559 host tests pass.

Not checked: the refusal under 75 KB free; a server on the internet or through the VPN; Wi-Fi lost mid-session; servers other than OpenSSH; nano, less, tmux; two-factor prompts; a session left open for hours.

Docs

Guide page and how-to (key login), FAQ, home page, Status Bar, SD card folders, the memory how-to, the Shell page, README, glossary, N1 notes, five screenshots.

🤖 Generated with Claude Code

https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

Closes #2. ## What it is A new **SSH App**: one session to a shell on another machine, over libssh (`ewpa/LibSSH-ESP32` 5.10.0) on mbedTLS. - `user@host[:port]`, typed in the App or as `ssh user@host` in the Shell. Up to eight hosts are remembered, once a login has succeeded. - **Trust on first use**, on the SHA-256 fingerprint. **A changed key is a warning**, with Cancel selected. - **A password, typed each time and stored nowhere**, or **a key the device makes for itself** (Ed25519): the public half is shown, written to `/ssh/id_ed25519.pub` and printed by `ssh status`. - **A real terminal** (`lib/term`, host-tested): enough for a shell, `less`, `top`, `nano`, `vim`. Sixteen colours, scroll regions, the alternate screen, 100 lines of scrollback. - **Q257 as asked: Ctrl with + and - change the text size**, five of them, from 60x20 to 26x8. The far end is told. - **Leaving the App doesn't end the session.** `SSH` shows in the Status Bar. The decisions (Q254 to Q266), the measurements and every check are in `docs/milestones/N1.md`. ## Three things beyond the App - **Keys that aren't characters now carry Shift, Ctrl and Alt** (`key_mapper.cpp`). The terminal needs it for Page Up and Alt+backtick. It also makes two documented keys work from the real keyboard that until now only worked from the Debug Console's `key` command: Ctrl+Fn+up/down in a note, Shift+Tab in Gemini. - **IRC doesn't try to connect with less than 60 KB free.** Started with a session open, its TLS handshake took the free heap down to 236 bytes, six times over. Now it says "not enough memory: close the SSH session" and waits. - **A build script** leaves libssh's own curve25519 out: libsodium (here for WireGuard) defines the same names. ## What it costs | | | |---|---| | Flash | **292 KB** (the trial said 120: signing with the device's key links a 109 KB table). The firmware is at 71% of its slot | | Heap, session open | about 50 KB of 99 KB | | Lowest free heap during a login | 30 KB | | Not started under | 75 KB free: not with IRC connected | ## Checked on the device Against OpenSSH 9.7 in a container: first-time trust (fingerprint compared with the server's), password, `ls`, `top`, `vim`, the five sizes with `stty size`, scrollback, leaving and coming back, Ctrl+C, backtick, both ways of ending, key login ("Accepted publickey" in the server's log), a changed host key (Cancel and Replace), a wrong password, a closed port, bad targets, forgetting a host, IRC waiting while a session is open, memory back to 99 KB after. 559 host tests pass. **Not checked:** the refusal under 75 KB free; a server on the internet or through the VPN; Wi-Fi lost mid-session; servers other than OpenSSH; `nano`, `less`, `tmux`; two-factor prompts; a session left open for hours. ## Docs Guide page and how-to (key login), FAQ, home page, Status Bar, SD card folders, the memory how-to, the Shell page, README, glossary, N1 notes, five screenshots. 🤖 Generated with [Claude Code](https://claude.com/claude-code) https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

twisla added 1 commit 2026-10-08 02:38:58 +00:00

SSH client: a terminal on another machine (#2 )

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6b71aace4f

The SSH App opens one session to a shell, over libssh (LibSSH-ESP32 5.10.0)
on mbedTLS. A server is trusted the first time on its fingerprint, and a
changed key is a warning with Cancel selected. The password is typed each
time and kept nowhere; or the device makes itself an Ed25519 key, whose
public half is shown, written to /ssh/id_ed25519.pub and printed by
`ssh status`.

lib/term is the terminal: what a shell, less, top, nano and vim send, with
sixteen colours, scroll regions, the alternate screen and 100 lines of
scrollback. Five text sizes with Ctrl and + or -, from 60x20 to 26x8, told
to the far end. The session goes on when the App is left; SSH shows in the
Status Bar. `ssh user@host` in the Shell opens the App.

Also:
- Keys that aren't characters carry Shift, Ctrl and Alt. The terminal needs
  it, and it makes Ctrl+Fn+up/down in a note and Shift+Tab in Gemini work
  from the real keyboard.
- IRC doesn't try to connect under 60 KB free: started with a session open,
  its TLS handshake took the heap down to 236 bytes.
- libssh's own curve25519 is left out of the build (scripts/libssh_filter.py):
  libsodium's has the same names.

Costs 292 KB of flash and about 50 KB of heap while a session is open; not
started under 75 KB free.

Docs: guide page, how-to, FAQ, home page, Status Bar, SD card folders, the
memory how-to, README, glossary, N1 notes with Q254 to Q266 and the checks.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

twisla added 1 commit 2026-10-08 07:06:43 +00:00

N1: the SSH client ships as v0.22.0

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079de4aec7

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

twisla merged commit 9dfe675db7 into main

2026-10-08 07:09:12 +00:00

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Reference: twisla/roro9stack#94