Cybersecurity and Ethical Hacking Tutorials

Create a private root CA on Linux with OpenSSL 3.x—passphrase-protected or unencrypted root key, self-signed certificate with CA extensions, verification, and safe key handling before you build an intermediate chain.

Free, hands-on Wireshark course covering packet capture, display filters, TCP analysis, TLS and IPsec decryption, and network troubleshooting.

Learn how to check whether SSH is using protocol 1 or 2, what OpenSSH version strings such as OpenSSH_7.4p1 mean, and how to read SSH-2.0 banners and verbose SSH output.

Automate password-based SSH and SCP in Linux using sshpass, Expect, and SSH_ASKPASS, with safer password input, host-key handling, and key-based alternatives.

Configure OpenSSH host-based authentication on Linux with HostbasedAuthentication, ssh-keysign, shosts.equiv, and verified host keys—plus hostname/DNS checks and safer alternatives.

Connect to private Linux servers through an SSH jump or bastion host using ProxyJump, ssh -J, ProxyCommand, and scp -J, with multi-hop routes and troubleshooting examples.

SSH from your host into a Linux VirtualBox VM using NAT port forwarding (recommended), host-only networking, or a bridged adapter — with a mode decision table, guest SSH checks, and troubleshooting for 10.0.2.15 and VPN …

Use OpenSSH host certificates so clients trust one host CA through @cert-authority in known_hosts instead of enrolling every server host key — create a host CA, sign with ssh-keygen -h, configure HostCertificate on sshd, …

Understand sshd ssh-rsa algorithm is disabled on RHEL 9 and 10, when RSA-SHA2 logins still work, and when to upgrade clients or allow a scoped ssh-rsa exception.

Sign files with ssh-keygen -Y sign, verify them with an allowed_signers file, signer identity, namespace, and stdin — no sshd or GPG required on OpenSSH 8.2 and later.

Fix SSH no matching key exchange method found by reading Their offer:, enabling the required KEX algorithm safely, and resolving follow-on host-key or cipher errors.

Fix SSH "Bad server host key: Invalid key length" caused by 1024-bit RSA host keys, RequiredRSASize, RHEL crypto policies, or stale known_hosts entries.

Free keytool tutorial for Java keystores and truststores: PKCS12, CSRs, chain imports, cacerts, PKIX fixes, and Spring Boot and Tomcat HTTPS on JDK 21.

Free OpenSSL and PKI tutorial: generate keys and CSRs, build a root and intermediate CA, issue SAN certificates, set up mTLS, then renew and revoke.

Free OpenSSH course: SSH keys, certificate authentication with a CA, sshd hardening, port forwarding, and file transfer, tested on RHEL and Ubuntu.

Free CompTIA PenTest+ (PT0-003) course with a Kali and Proxmox lab, all five exam domains, and hands-on labs for recon, AD, web, and reporting.

Free, hands-on ethical hacking course on Kali Linux covering lab setup, recon, password cracking, phishing, web, wireless, and mobile attacks.

Fix userauth_pubkey: key type ssh-rsa not in PubkeyAcceptedKeyTypes by using rsa-sha2 with the same RSA key, or Ed25519, before any legacy ssh-rsa exception.

Create and update an OpenSSH Key Revocation List (KRL), revoke SSH certificates by serial, Key ID, or fingerprint, revoke plain public keys, and make sshd enforce RevokedKeys.

Set up OpenSSH user certificate authentication with an SSH CA: create TrustedUserCAKeys, sign keys with principals and expiry, verify login, revoke with a KRL, then map principals with AuthorizedPrincipalsFile.

Configure OpenSSH authentication in sshd_config: password, public key, keyboard-interactive, host-based, GSSAPI, AuthenticationMethods, and Match blocks on Linux.

OpenSSH PerSourcePenalties on Linux: how sshd temporarily refuses noisy source addresses, how to read defaults with sshd -T, how to fix Not allowed at this time, and how exemptions and MaxAuthTries differ from Fail2ban.

Understand RPM signing changes on RHEL 10 and 10.1: Sequoia PGP verification, RPMv6 signatures, multiple signatures, OpenPGP v6, and hybrid ML-DSA-87+Ed448 post-quantum signing with tested commands.

Test archived L3MON on Kali with Genymotion: start the panel, patch and install a lab APK, verify client behavior, then analyze the APK with aapt, apktool, and JADX.

Create Thinkst Canarytokens on canarytokens.org, test a Web bug from Kali with curl, read the alert history, then choose document, AWS, Kubernetes, cloned-site, and MCP honeytokens for authorized detection.

Install Ghost Framework 8.0.0 on Kali, connect it to a Genymotion Android 10 guest over ADB, enumerate the device, and compare Ghost commands with direct adb shell in an authorized lab.

Test the old ADB Android lock screen bypass claims on rooted Genymotion, see why gesture.key fails on modern Android, and learn which recovery options still apply.

Install Zphisher on Kali Linux, run a Facebook-style login template on localhost, submit dummy form data with curl, and inspect auth capture files to see how the phishing workflow works.

Review FiercePhish as a legacy Laravel phishing framework: inspect the official installer, note Ubuntu-only limits on modern Linux, and map campaign concepts without live delivery.

Create harmless PDF payload examples with JavaScript, embedded attachments, and URLs, then analyze them on Kali with PDFiD, pdf-parser, ExifTool, and qpdf.