UNPROTECTED PRIVATE KEY FILE 🐧 Linux

WARNING: UNPROTECTED PRIVATE KEY FILE! Permissions 0644 for 'key.pem' are too open

SSH refuses to use a private key that other users can read; it must be readable only by you (chmod 600).

Seen on: Linux

Meaning

Keys downloaded from cloud consoles, copied from Windows or stored on a mounted drive often get 0644/0777 permissions. On WSL/NTFS mounts chmod may not stick — copy the key into the Linux home directory.

Common causes

  • Key file mode 0644/0664/0777
  • Key on an NTFS/Windows mount (WSL) where permissions aren’t enforced
  • Wrong owner after copying with sudo

⚡ Quick fix

  1. chmod 600 the key (400 also works)
  2. Make sure you own it: chown $USER
  3. On WSL, copy the key to ~/.ssh inside Linux

Detailed fix by platform

Shell

  1. bash
    chmod 600 ~/.ssh/key.pem
chmod 700 ~/.ssh

Windows

  1. powershell
    icacls .\key.pem /inheritance:r
icacls .\key.pem /grant:r "$($env:USERNAME):(R)"

How to diagnose

  1. Mode — ls -l key.pem
  2. Owner — Your user?
  3. Filesystem — On /mnt/c?

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