How to fix Permissions 0644 for '/home/user/.ssh/id_rsa' are too open. It is required that your private key files are NOT accessible by others. in Git

First, identify the exact permissions on your private key file:

# Check permissions on the default RSA key
ls -la ~/.ssh/id_rsa

# Or for ED25519 keys
ls -la ~/.ssh/id_ed25519

# For custom key files
ls -la ~/.ssh/your_key_name

The output shows permissions like:
- -rw-r--r-- (0644) - Too open, everyone can read
- -rwxr-xr-x (0755) - Too open, everyone can read and execute
- -rw------- (0600) - Correct, only owner can read/write
- -r-------- (0400) - Correct, only owner can read

If the middle and last groups have any permissions (not ---), the key is too open.

The standard fix is to restrict permissions so only you can read the key:

On Linux/macOS:

# Fix a specific key file
chmod 600 ~/.ssh/id_rsa

# Or make it read-only (more restrictive)
chmod 400 ~/.ssh/id_rsa

# Fix multiple keys at once
chmod 600 ~/.ssh/id_*
chmod 644 ~/.ssh/*.pub  # Public keys can be readable by others

Verify the fix:

ls -la ~/.ssh/id_rsa
# Should show: -rw------- (0600) or -r-------- (0400)

Permission breakdown:
- 600 = owner read+write, no group/other access
- 400 = owner read-only, no group/other access (more secure)

Both values work; 600 is more common as it allows you to modify the file later.

The .ssh directory itself also needs correct permissions:

# Set correct permissions on .ssh directory
chmod 700 ~/.ssh

# Verify
ls -la ~ | grep .ssh
# Should show: drwx------ (0700)

Complete permission setup for SSH:

# Directory
chmod 700 ~/.ssh

# Private keys (no extension or custom names)
chmod 600 ~/.ssh/id_rsa
chmod 600 ~/.ssh/id_ed25519
chmod 600 ~/.ssh/id_ecdsa

# Public keys (.pub files)
chmod 644 ~/.ssh/id_rsa.pub
chmod 644 ~/.ssh/id_ed25519.pub

# Config file
chmod 600 ~/.ssh/config

# Known hosts
chmod 644 ~/.ssh/known_hosts

# Authorized keys (for incoming SSH)
chmod 600 ~/.ssh/authorized_keys

The directory needs execute permission (7) because execute on a directory means you can access files inside it.

Windows doesn't use Unix-style permissions, but OpenSSH for Windows still checks file security:

Using Git Bash (recommended):

chmod 600 ~/.ssh/id_rsa

Using PowerShell:

# Remove inheritance and set owner-only access
$keyPath = "$env:USERPROFILE\.ssh\id_rsa"

# Remove all existing permissions
icacls $keyPath /inheritance:r

# Grant read permission only to current user
icacls $keyPath /grant:r "$($env:USERNAME):(R)"

Using Windows GUI:
1. Right-click the key file and select "Properties"
2. Go to the "Security" tab
3. Click "Advanced"
4. Click "Disable inheritance" and choose "Remove all inherited permissions"
5. Click "Add" to add your user with "Read" permission only
6. Remove all other users/groups

Note: If using WSL (Windows Subsystem for Linux), keys in the Linux filesystem (/home/user/.ssh) work with chmod. Keys in the Windows filesystem (/mnt/c/Users/...) may need Windows permission tools.

After fixing permissions, test that SSH accepts the key:

Test SSH connection to GitHub:

ssh -T [email protected]

Expected output:

Hi username! You've successfully authenticated, but GitHub does not provide shell access.

Test SSH connection to GitLab:

ssh -T [email protected]

Test SSH connection to Bitbucket:

ssh -T [email protected]

Debug connection issues:

# Verbose output shows which keys SSH tries
ssh -vT [email protected]

# Very verbose for more detail
ssh -vvT [email protected]

If the connection works, your Git operations over SSH should now succeed.

Some filesystems don't support Unix permissions, causing this error even after chmod:

FAT32/exFAT drives:
These filesystems don't store Unix permissions. Copy the key to a native filesystem:

# Copy from USB drive to home directory
cp /mnt/usb/id_rsa ~/.ssh/
chmod 600 ~/.ssh/id_rsa

Docker containers:
Volume mounts may not preserve permissions. Options:

# Option 1: Copy key and fix permissions in Dockerfile
COPY id_rsa /root/.ssh/id_rsa
RUN chmod 600 /root/.ssh/id_rsa

# Option 2: Use secrets (Docker Swarm or Kubernetes)
# Option 3: Use ssh-agent forwarding instead of copying keys

Docker Compose with correct permissions:

services:
  app:
    volumes:
      - ~/.ssh/id_rsa:/root/.ssh/id_rsa:ro
    # Note: :ro makes it read-only but doesn't fix permissions

NFS mounts:
NFS can map permissions. Check your NFS export options and mount options for no_root_squash or similar settings.