Networking · Lesson 20 of 26 · 8 minutes

SSH dry-run review

Resolve SSH config and key context without connecting.

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learner@clairos:~ $

↑ history · Tab complete · Ctrl+C cancel · Esc, Tab to leaveExit 0

Your objectives

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1
Resolve lab SSH config
Run ssh -G lab.
Hint & worked example
Inspect a fixed SSH training scenario; no real remote connection is made.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
ssh -G lab
```
Remember: Verify host identity and choose credentials deliberately on real systems.
2
Read SSH config
Run cat ~/.ssh/config.
Hint & worked example
Read one or more files to standard output without editing their contents.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
cat ~/.ssh/config
```
Remember: Reading a source file should precede changing it; avoid printing real secrets.
3
Inspect known hosts
Run stat ~/.ssh/known_hosts.
Hint & worked example
Inspect a file or directory metadata record, including ownership, permissions, and size.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
stat ~/.ssh/known_hosts
```
Remember: Metadata and file contents answer different questions.

Understand the pattern

Junior operators build confidence by gathering evidence before changing systems.

ssh: Inspect a fixed SSH training scenario; no real remote connection is made.
Verify host identity and choose credentials deliberately on real systems.
cat: Read one or more files to standard output without editing their contents.
Reading a source file should precede changing it; avoid printing real secrets.
stat: Inspect a file or directory metadata record, including ownership, permissions, and size.
Metadata and file contents answer different questions.

Worked example and expected result

$ ssh -G lab

host lab
user learner
hostname clairos-learn-lab
identityfile ~/.ssh/training_key
pubkeyauthentication yes
passwordauthentication no

Exit status: 0. The command completed successfully in the training fixture.

$ cat ~/.ssh/config

Host lab
  HostName clairos-learn-lab
  User learner
  IdentityFile ~/.ssh/training_key

Exit status: 0. The command completed successfully in the training fixture.

$ stat ~/.ssh/known_hosts

Path: /home/learner/.ssh/known_hosts
Type: file
Mode: -rw-------
Owner: learner
Group: learners
Size: 84 bytes

Exit status: 0. The command completed successfully in the training fixture.

Try a variation

Repeat this workflow in the sandbox with a different scratch filename. Keep the system fixtures unchanged and compare the observed output with your expectation before moving on.

Explain it

In “SSH dry-run review”, which interpretation is safe?Reading a source file should precede changing it; avoid printing real secrets.A command appearing in history proves it completed successfully.A successful first check guarantees that every dependent service is healthy.

Apply it elsewhere

Before adapting the cat workflow from “SSH dry-run review” to another server, what should you do?Paste the training paths unchanged into production.Skip output inspection whenever the command is familiar.Confirm the current directory, target identity, permissions, and the installed command behavior first.

Keep the momentum.

Complete the lab, then explain and apply the pattern.

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