How to Fix SSH Key Permissions and Automate Auth Inside WSL

Running SSH inside Windows Subsystem for Linux (WSL) can cause authentication failures because Windows NTFS-mounted drives assign permissive 0777 permissions to all files, conflicting with OpenSSH's strict POSIX permission requirements. The root cause is that WSL mounts Windows drives under /mnt/c/ using a translation layer that ignores standard Linux file ownership and access controls. To avoid these errors, SSH keys should be generated and stored exclusively within WSL's native ext4 file system at ~/.ssh, using the Ed25519 algorithm for stronger security and compact key size. Strict permissions must then be enforced manually — 700 on the directory, 600 on the private key, and 644 on the public key — to satisfy OpenSSH's security checks. Passphrase re-entry friction can be eliminated by configuring ssh-agent to cache credentials in memory and auto-loading it via a conditional block in ~/.bashrc for every new shell session.