How to fix It is required that your private key files are NOT accessible by others. in SSH

First, verify what permissions your private key currently has:

ls -l ~/.ssh/id_rsa

Or check all files in your SSH directory:

ls -la ~/.ssh/

Look for your private key file (typically named id_rsa, id_ed25519, id_ecdsa, or a custom name). The permissions will show something like:

- -rw------- 1 user group (600) - CORRECT, only you can read/write
- -rw-r--r-- 1 user group (644) - WRONG, group and others can read
- -rwxrwxrwx 1 user group (777) - WRONG, everyone has full access

If you see anything other than 600 for the private key, proceed to the next step.

Set the private key to be readable and writable by only the owner:

chmod 600 ~/.ssh/id_rsa

Replace id_rsa with your actual key filename if it's different (e.g., id_ed25519, github-key).

Verify the fix:

ls -l ~/.ssh/id_rsa

Should now show: -rw------- 1 user user (600 permissions)

Your .ssh directory must also have restrictive permissions (700):

chmod 700 ~/.ssh

Verify:

ls -ld ~/.ssh

Should show: drwx------ ... user user (700 permissions)

This ensures that only you can list, read, or modify files in your SSH directory.

While you're at it, set correct permissions for all SSH files:

# Fix public key (readable by anyone, but only writable by you)
chmod 644 ~/.ssh/id_rsa.pub

# Fix authorized_keys (readable/writable only by you)
chmod 600 ~/.ssh/authorized_keys

# Fix known_hosts (readable/writable only by you)
chmod 600 ~/.ssh/known_hosts

# Fix config file if present (readable/writable only by you)
chmod 600 ~/.ssh/config

Summary of correct SSH permissions:
- ~/.ssh directory: 700 (drwx------)
- Private keys (id_rsa, id_ed25519): 600 (-rw-------)
- Public keys (id_rsa.pub): 644 (-rw-r--r--)
- authorized_keys: 600 (-rw-------)
- known_hosts: 600 (-rw-------)
- config: 600 (-rw-------)

After fixing permissions, test that SSH now works:

ssh -i ~/.ssh/id_rsa [email protected]

Or test with a specific key using verbose mode to debug:

ssh -vvv -i ~/.ssh/id_rsa [email protected]

The verbose output should show:

Trying private key: /home/user/.ssh/id_rsa
...
Authentications that can continue: publickey
...
Authenticated with RSA key

If SSH still fails, the issue is not permissions—check that your public key is in authorized_keys on the remote server.

When generating new SSH keys, ensure proper permissions from the start:

# Generate a new key (automatically creates it with 600 permissions)
ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519 -N ""

# Or with RSA (if you need wider compatibility)
ssh-keygen -t rsa -b 4096 -f ~/.ssh/id_rsa -N ""

The ssh-keygen tool creates private keys with 600 permissions automatically. Just verify:

ls -l ~/.ssh/id_ed25519

Should show -rw------- ... (600).