https://mrtomlinux.org/tags/multiplexing/ Recent content in Multiplexing on Linux Café Hugo en Sun, 20 Sep 2026 12:02:28 +0200 https://mrtomlinux.org/post/2026-09-20-why-ssh-keeps-spawning-new-processes-on-every/ Sun, 20 Sep 2026 12:02:28 +0200 https://mrtomlinux.org/post/2026-09-20-why-ssh-keeps-spawning-new-processes-on-every/ <h2 id="why-ssh-keeps-spawning-new-processes-on-every-connect">Why SSH keeps spawning new processes on every connect</h2> <p>Every time I run <code>ssh host</code>, the client forks a new process that talks to the remote <code>sshd</code>.<br> On the server side, <code>sshd</code> spawns a child for each accepted connection.<br> The model is simple and works fine for a handful of sessions, but it starts to feel like a drain when you:</p> <ul> <li>run a script that opens dozens of SSH connections in a row,</li> <li>use CI/CD pipelines that hit a remote host repeatedly, or</li> <li>have a home‑lab with many small services that need quick SSH access.</li> </ul> <p>Each fork eats a few kilobytes of RAM and a handful of file descriptors.<br> If you hit the per‑user process limit (<code>ulimit -u</code>) or the system’s <code>max_user_processes</code>, you’ll see “Too many users” or “Connection refused” errors.<br> Even on a modest machine, the cumulative CPU cost of negotiating the SSH handshake over and over can add up.</p>