On macOS, Linux, and other Unix-like systems, restrict access to the private key: chmod 600 /path/to/private_key. This gives the file’s owner read/write access and removes access for group and other users. OpenSSH ignores a private key file accessible by others, so making it more permissive is not a fix. [OpenBSD ssh(1) manual]
What the “too open” warning means
OpenSSH checks that a private identity file is not accessible to other users. Its ssh(1) manual says it “will simply ignore a private key file if it is accessible by others.” The warning is therefore a security check: the client is declining to use a key whose file permissions expose it. [OpenBSD ssh(1) manual]
As an Amazon Associate I earn from qualifying purchases.
The fix is usually to restrict the existing private key, not replace it or generate a new one. The command below is for POSIX-style permissions; it is not a universal Windows ACL command.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsFind the exact private key SSH is using
Change the permissions on the private identity file named in the warning, not on a similarly named file chosen by guesswork. A key may be selected with SSH’s -i option or through an IdentityFile setting. Typical private-key paths include ~/.ssh/id_ed25519 and ~/.ssh/id_rsa; the corresponding public-key file commonly ends in .pub. The client manual distinguishes the private identity file from its associated public key. [OpenBSD ssh(1) manual]
#1 Best Overall
- POWERFUL SECURITY KEY: The Security Key C NFC is the essential physical passkey for protecting your digital life from phishing attacks. It ensures only you can access your accounts.
- WORKS WITH 1000+ ACCOUNTS: Compatible with Google, Microsoft, and Apple. A single Security Key C NFC secures 100 of your favorite accounts, including email, password managers, and more.
- FAST & CONVENIENT LOGIN: Plug in your Security Key C NFC via USB-C and tap it, or tap it against your phone (NFC) to authenticate. No batteries, no internet connection, and no extra fees required.
- TRUSTED PASSKEY TECHNOLOGY: Uses the latest passkey standards (FIDO2/WebAuthn & FIDO U2F) but does not support One-Time Passwords. For complex needs, check out the YubiKey 5 Series.
- BUILT TO LAST: Made from tough, waterproof, and crush-resistant materials. Manufactured in Sweden and programmed in the USA with the highest security standards.
Restrict the private key on Unix-like systems
-
Inspect the file’s current mode, substituting the actual key path:
ls -l /path/to/private_key -
Remove group and other access:
chmod 600 /path/to/private_key -
Retry the same SSH connection or agent operation that produced the warning.
Rank #2
Yubico - YubiKey 5C NFC - Multi-Factor authentication (MFA) Security Key and passkey, Connect via USB-C or NFC, FIDO Certified - Protect Your Online Accounts- POWERFUL SECURITY KEY: The YubiKey 5C NFC is the most versatile physical passkey, protecting your digital life from phishing attacks. It ensures only you can access your accounts
- WORKS WITH 1000+ ACCOUNTS: Compatible with popular accounts like Google, Microsoft, and Apple. A single YubiKey 5C NFC secures 100+ of your favorite accounts, including email, password managers, and more
- FAST & CONVENIENT LOGIN: Plug in your YubiKey 5C NFC via USB and tap it, or tap it against your phone (NFC), to authenticate. No batteries, no internet connection, and no extra fees required
- MOST SECURE PASSKEY: Supports FIDO2/WebAuthn, FIDO U2F, Yubico OTP, OATH-TOTP/HOTP, Smart card (PIV), and OpenPGP. That means it’s versatile, working almost anywhere you need it
- PRIMARY & SPARE KEYS: Just like having a spare house key, we recommend buying two YubiKeys - one for daily use and one as a spare. That way you’ll never get locked out of your accounts
Mode 600 means the owner can read and write the file; group and other users have no permissions. That matches OpenSSH’s requirement that the user be able to read the private key while others cannot access it. [OpenBSD ssh(1) manual]
Do not use chmod 777 or grant broad read access. Those settings make the file more accessible and undermine the protection the client is checking.
Rank #3
- POWERFUL SECURITY KEY: The YubiKey 5 NFC is the most versatile physical passkey, protecting your digital life from phishing attacks. It ensures only you can access your accounts
- WORKS WITH 1000+ ACCOUNTS: Compatible with popular accounts like Google, Microsoft, and Apple. A single YubiKey 5 NFC secures 100+ of your favorite accounts, including email, password managers, and more
- FAST & CONVENIENT LOGIN: Plug in your YubiKey 5 NFC via USB and tap it, or tap it against your phone (NFC), to authenticate. No batteries, no internet connection, and no extra fees required
- MOST SECURE PASSKEY: Supports FIDO2/WebAuthn, FIDO U2F, Yubico OTP, OATH-TOTP/HOTP, Smart card (PIV), and OpenPGP. That means it’s versatile, working almost anywhere you need it
- PRIMARY & SPARE KEYS: Just like having a spare house key, we recommend buying two YubiKeys - one for daily use and one as a spare. That way you’ll never get locked out of your accounts
If the warning remains, check the directory and ownership
Confirm that the key belongs to the account running SSH and inspect its containing .ssh directory. OpenBSD’s manual recommends that .ssh be accessible to its owner and inaccessible to others. It also says the SSH configuration file must not be writable by others; follow the exact error message to identify which object needs attention rather than changing every file indiscriminately. [OpenBSD ssh(1) manual]
Keep private-key and public-key permissions distinct
The private key is the credential the user protects. The public key is meant to be provided to the server for public-key authentication. A warning that a private key is accessible by others concerns the private identity file, not the public key’s separate role. [OpenBSD ssh(1) manual] [OpenBSD ssh(1) manual]
Rank #4
- POWERFUL SECURITY KEY: The Security Key NFC is the essential physical passkey for protecting your digital life from phishing attacks. It ensures only you can access your accounts.
- WORKS WITH 1000+ ACCOUNTS: Compatible with Google, Microsoft, and Apple. A single Security Key NFC secures 100 of your favorite accounts, including email, password managers, and more.
- FAST & CONVENIENT LOGIN: Plug in your Security Key NFC via USB-A and tap it, or tap it against your phone (NFC) to authenticate. No batteries, no internet connection, and no extra fees required.
- TRUSTED PASSKEY TECHNOLOGY: Uses the latest passkey standards (FIDO2/WebAuthn & FIDO U2F) but does not support One-Time Passwords. For complex needs, check out the YubiKey 5 Series.
- BUILT TO LAST: Made from tough, waterproof, and crush-resistant materials. Manufactured in Sweden and programmed in the USA with the highest security standards.
When the SSH agent is involved
ssh-add loads private-key identities into ssh-agent, and it applies its own access check: it ignores identity files accessible by others. If a direct SSH attempt and agent loading behave differently, check which identity file is being passed to ssh-add and whether it is the same path SSH is using. [OpenBSD ssh-add(1) manual]
Free tools Windows power users keep installed
One-click scans. No signup required.
Windows and other ACL-based setups
The chmod example applies to Unix-style file permissions. Windows OpenSSH may rely on access control lists (ACLs), and the correct steps depend on the Windows release, filesystem, and account setup. Do not treat the Unix command as a Windows fix; use current official instructions for the specific Windows environment instead.
Quick Recap
Best Value
- The information below is per-pack only
- POWERFUL SECURITY KEY: The Security Key C NFC is the essential physical passkey for protecting your digital life from phishing attacks. It ensures only you can access your accounts.
- WORKS WITH 1000+ ACCOUNTS: Compatible with Google, Microsoft, and Apple. A single Security Key C NFC secures 100 of your favorite accounts, including email, password managers, and more.
- FAST & CONVENIENT LOGIN: Plug in your Security Key C NFC via USB-C and tap it, or tap it against your phone (NFC) to authenticate. No batteries, no internet connection, and no extra fees required.
- TRUSTED PASSKEY TECHNOLOGY: Uses the latest passkey standards (FIDO2/WebAuthn & FIDO U2F) but does not support One-Time Passwords. For complex needs, check out the YubiKey 5 Series.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
