Linux Networking
Unscored tasks with hints and instant feedback. Practice results never become credentials.
Short lesson
Combine small tools: grep filters lines, awk/cut pick fields, sort | uniq -c counts, xargs turns lines into arguments. Read logs with journalctl -u UNIT.
What IP address does db.internal resolve to? Enter it as your answer.
Sign up to practiseWhich program is listening on TCP port 5432? Enter the program name.
Sign up to practiseThe app must reach api.internal at 10.0.5.20, but DNS has no record yet. Add a local override so `curl -s http://api.internal/health` returns OK.
Sign up to practiseEnable the firewall (ufw) so the server only accepts SSH (22) and HTTPS (443) by default-deny incoming.
Sign up to practiseCreate an ed25519 key pair at ~/.ssh/id_ed25519 without a passphrase, and authorise its public key for your own account (~/.ssh/authorized_keys, mode 600).
Sign up to practiseLock down SSH: disable password authentication and root login in /etc/ssh/sshd_config, validate the config, and reload sshd. Keep port 22.
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