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chmod 600 Explained

rw-------

chmod 600 ensures that only the file owner can read and write to the file. All group members and public users have zero permissions. It is strictly mandated by OpenSSH for private cryptographic keys.

Interactive chmod 600 Calculator

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Ready-to-run Linux command
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Permission Checkbox Matrix

Click any permission to recalculate instantly
User / Owner (u)
File creator / owner
Total:7
Group (g)
Assigned user group
Total:5
Others / Public (o)
All other system users
Total:5
4thAdvanced / Special Permissions (SUID, SGID, Sticky Bit)
Dynamic Permission Translation
Owner:Read, Write, Execute (Full access)
Group:Read, Execute
Others:Read, Execute
File vs Directory Semantics

For Files: x allows binary or script execution.
For Directories: x is the search/traverse bit, required to cd into the directory and access inner files. Without directory execute, users cannot open subdirectories even with read rights!

Quick Permission PresetsClick to apply
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Bit Breakdown for 600

Owner (6)
4 + 2 + 0 = 6
rw- (Read & Write)
Group (0)
0 + 0 + 0 = 0
--- (No Access)
Others (0)
0 + 0 + 0 = 0
--- (No Access)

Fixing "UNPROTECTED PRIVATE KEY FILE" in SSH

If you ever tried to connect to a server using ssh -i ~/.ssh/id_rsa user@host and received this error:

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: UNPROTECTED PRIVATE KEY FILE! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
Permissions 0644 for 'id_rsa' are too open.
It is required that your private key files are NOT accessible by others.
Load key "id_rsa": bad permissions
Permission denied (publickey).

The OpenSSH security daemon detects that other users on the operating system could theoretically read your cryptographic private key. To resolve this error instantly, run:

chmod 600 ~/.ssh/id_rsa

Other Files That Should Always Be chmod 600

  • Environment Secrets: Production .env, .env.production, or secrets.yaml files storing API keys and JWT secrets.
  • Database Password Configs: WordPress wp-config.php or MySQL client defaults ~/.my.cnf.
  • Shell History: ~/.bash_history or ~/.zsh_history which might inadvertently log plaintext command-line passwords.
← chmod 400 for AWS .pem keyschmod 700 for ~/.ssh directory →