Working notes on SSH: Keys, Reconnect, SSH, and SSH debug.
Topics
Keys
Generate RSA keys, drop a host from known_hosts, and load a .pem with ssh-add.
Reconnect
List and reattach GNU screen sessions with sudo screen -list and -d -r.
SSH
Configure sshd, place authorized_keys, set permissions, restart the Ubuntu ssh service, and lock down root password login.
SSH debug
Test sshd config, run a parallel debug daemon on another port, and connect with ssh -vvv.
Updated:
2026 Aug 19
