Security administration · Lesson 28 of 35 · 8 minutes

Hardening header review

Inspect web security header config and static API blocking.

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Your objectives

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1
Find CSP
Run grep Content-Security-Policy /etc/nginx/sites-available/learn.conf.
Hint & worked example
Select input lines that match a pattern; -i ignores case, -n adds line numbers, and -v inverts selection.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
grep Content-Security-Policy /etc/nginx/sites-available/learn.conf
```
Remember: No matches is exit status 1, which is different from a malformed invocation.
2
Find API rules
Run grep /api/ /etc/nginx/sites-available/learn.conf.
Hint & worked example
Select input lines that match a pattern; -i ignores case, -n adds line numbers, and -v inverts selection.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
grep /api/ /etc/nginx/sites-available/learn.conf
```
Remember: No matches is exit status 1, which is different from a malformed invocation.
3
Validate config
Run nginx -t.
Hint & worked example
Check the simulated configuration using nginx -t before changing service state.
The command outcome must match the task, including successful access or the explicitly requested failure.
```
nginx -t
```
Remember: This lab checks a limited configuration subset, not the complete Nginx parser.

Understand the pattern

Junior operators build confidence by gathering evidence before changing systems.

grep: Select input lines that match a pattern; -i ignores case, -n adds line numbers, and -v inverts selection.
No matches is exit status 1, which is different from a malformed invocation.
nginx: Check the simulated configuration using nginx -t before changing service state.
This lab checks a limited configuration subset, not the complete Nginx parser.

Worked example and expected result

$ grep Content-Security-Policy /etc/nginx/sites-available/learn.conf

  add_header Content-Security-Policy "default-src 'self'; connect-src 'self'" always;

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

$ grep /api/ /etc/nginx/sites-available/learn.conf

  location ^~ /api/learn/ { proxy_pass http://127.0.0.1:8010; }
  location ^~ /api/ { return 404; }

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

$ nginx -t

nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful

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 “Hardening header review”, which interpretation is safe?A successful first check guarantees that every dependent service is healthy.No matches is exit status 1, which is different from a malformed invocation.A command appearing in history proves it completed successfully.

Apply it elsewhere

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

Keep the momentum.

Complete the lab, then explain and apply the pattern.

Next: Service exposure note Try an incident drill

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