MistLab Engineering

Series

Building an SSH Terminal

A series on how an SSH terminal client works, from bytes and the PTY up through paste, locales, and ZMODEM.

Oct 31, 2026
Oct 31, 20269 min read1 view
Finding ZMODEM in a Terminal Byte Stream: How `rz`/`sz` Works Inside an SSH Client
How rz/sz and ZMODEM work over SSH: frame headers, intent-gated detection, PTY takeover, untrusted names and cancel.
9 min read1 view
Nov 2, 2026
Nov 2, 202611 min read
Command Auditing in an SSH Terminal: What the Client Can See, and What Only the Server Can Enforce
SSH command auditing: client hints vs server ForceCommand, bash DEBUG hooks, and forgeable in-band markers.
11 min read