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Mission / Euler CPU
01 / 0545 active minutescredentials

Establish Safe Euler SSH Access

Password access is proven first, a dedicated passphrase-protected key is created without overwriting existing keys, only its .pub file is installed, key-only authentication succeeds, and a validated euler alias preserves unrelated SSH configuration.

Work herelocal / powershell or zsh or bash
  1. 1Understand
  2. 2Do
  3. 3Check
  4. 4Submit
Learn firstConcept, example, trap and recovery

Outcome#

Password access is proven first, a dedicated passphrase-protected key is created without overwriting existing keys, only its .pub file is installed, key-only authentication succeeds, and a validated euler alias preserves unrelated SSH configuration.

Concept#

Generating keys cannot repair missing Euler entitlement or a wrong username. Testing password access first separates account problems from key problems. Dedicated filenames and backups prevent accidental damage to other SSH hosts.

Worked Example#

Key-only SSH prints config-ok; IdentityFile names a private key, never a .pub file, and no existing key was overwritten.

A correct example uses these decisions:

  • Which file must IdentityFile reference? The private key path without .pub.
  • What is the safe default when a target key or config already exists? Stop, back it up, inspect it, and avoid overwriting.

Common Trap#

Running PowerShell at an Euler Bash prompt, concatenating Host blocks, or pointing IdentityFile at the public .pub key.

If Blocked#

Stop at the first failed gate. Do not regenerate repeatedly, overwrite keys, replace the whole SSH config, or loosen permissions broadly. Use Euler SSH troubleshooting and share only the exact error plus sanitized ssh -G fields.

Useful references:

Understand Before Accepting AI Output#

Inspect every path and backup before accepting an SSH repair. A .pub file in IdentityFile, concatenated host blocks, or PowerShell pasted into Euler Bash are configuration errors, not reasons to delete all SSH state.

Do the mission

One bounded attempt

Pass: 100% + every safety item
Action

Use the read-only SSH preflight first. If a key is missing, follow the no-overwrite platform procedure, preview the config, validate with ssh -G, then test key-only access.

Expected

Key-only SSH prints config-ok; IdentityFile names a private key, never a .pub file, and no existing key was overwritten.

Run only the commands for your machine

Step 1windows / powershell
ssh -G euler | Select-Object -First 40

Expected: OpenSSH parses the configuration without an error.

Step 2windows / powershell
ssh -o PreferredAuthentications=publickey -o PasswordAuthentication=no euler "echo config-ok"

Expected: After the key passphrase, the remote command prints config-ok without an ETH password prompt.

Step 3macos / zsh
ssh -G euler | sed -n '1,40p'

Expected: OpenSSH parses the configuration without an error.

Step 4macos / zsh
ssh -o PreferredAuthentications=publickey -o PasswordAuthentication=no euler "echo config-ok"

Expected: After the key passphrase, the remote command prints config-ok without an ETH password prompt.

Step 5linux / bash
ssh -G euler | sed -n '1,40p'

Expected: OpenSSH parses the configuration without an error.

Step 6linux / bash
ssh -o PreferredAuthentications=publickey -o PasswordAuthentication=no euler "echo config-ok"

Expected: After the key passphrase, the remote command prints config-ok without an ETH password prompt.

01Which file must IdentityFile reference?Safety-critical
02What is the safe default when a target key or config already exists?Safety-critical
Confirm the result you personally observed

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