Topics
Security
Data formats
Text
Linux and network
Encoding and conversion
Where to start
First steps
15 stages · From system basics and command input to navigation, files, text, and pipelines.
Track map 11 tracks · 123 stages
Difficulty
New labs
Sections 183 articles
Command index 432
Popular
Web stack
Read the output
$ curl https://app.lab.test/ curl: (60) SSL certificate problem: unable to get local issuer certificate $ openssl s_client -connect app.lab.test:443 </dev/null 2>/dev/null | grep -A1 ' s:' 0 s:CN = app.lab.test i:O = Lab, CN = Lab Issuing CA
curl --cacert lab-issuing-ca.crt
ssl_certificate