security
How to Install keytool on Ubuntu
Fix keytool command not found on Ubuntu by installing OpenJDK (default-jdk or openjdk-21-jdk), set JAVA_HOME and PATH, verify with keytool -help, run a PKCS12 smoke test, update through apt, and uninstall cleanly.
security
OpenSSL vs LibreSSL vs BoringSSL: Which TLS Library Should You Use?
Compare OpenSSL, LibreSSL, and BoringSSL for TLS and cryptography: intended audience, API stability, FIPS, how Linux distributions package each library, and when each is the right choice—with commands to verify what your …
cheatsheet
OpenSSL Command Cheat Sheet: Keys, Certificates, TLS & PKCS#12
OpenSSL is the standard CLI for TLS keys, X.509 certificates, CSRs, chain verification, PKCS#12 bundles, file encryption, and live HTTPS inspection. This cheat sheet covers everyday subcommands with copy-paste tables and …
security
PKI, Certificates, CA, CRL, and OCSP Explained for Beginners
Beginner-friendly PKI tutorial: public keys, X.509 certificates, Certificate Authorities, trust chains, SAN extensions, PEM and PFX formats, CRL vs OCSP revocation, TLS and mTLS handshakes—with diagrams and OpenSSL …
security
How to Create PKCS12 from CRT and KEY with OpenSSL
Create a PKCS12 (.p12) keystore from CRT and KEY with OpenSSL pkcs12 -export for Java keytool, Oracle JSSE, and IBM apps. Covers alias, chain, self-signed certs, -legacy for older Java, cert-only bundles, and …
security
How to Create a PFX from CRT and KEY with OpenSSL
Create a PFX or P12 file from CRT and KEY with OpenSSL pkcs12 -export: add intermediate chain with -certfile, set export password with -passout, and use -legacy for Windows IIS. Copy-paste examples with verification …
security
How to Extract a Private Key from PFX with OpenSSL
Use OpenSSL pkcs12 to extract a private key, certificate, and CA chain from a PFX or P12 file on Linux. Covers password-protected and empty-password PFX, unencrypted PEM for nginx, -legacy for old Windows exports, and …
security
How to Verify a Certificate Matches a Private Key with OpenSSL
Verify a certificate matches a private key with OpenSSL: compare RSA modulus MD5 hashes, use pkey -pubout for EC and ECDSA, check CSR alignment, and test encrypted keys. Covers nginx mismatch errors and copy-paste …
security
How to Install OpenSSL on Ubuntu
Install OpenSSL on Ubuntu with apt (openssl and libssl-dev), verify with openssl version, understand when the distro package is enough versus building from source, and generate a test TLS key and certificate.
security
How to Generate a Self-Signed Certificate with OpenSSL
Generate a self-signed SSL certificate with OpenSSL in one command or via CSR: RSA 2048/4096, EC, Ed25519, SAN for localhost and IP addresses, encrypted keys, and nginx-ready PEM files. Copy-paste examples with real …
security
How to setup http/https proxy with special characters in password
How to export the variable "http_proxy" or "https_proxy" when there are special characters in username or password in Linux?
security
Setup & verify Mutual TLS Authentication (MTLS) with OpenSSL
With mutual TLS authentication (MTLS), not only does the service side prove its identity by exposing a certificate, but also the clients prove their identity to the servers by exposing a client-side certificate.
security
OpenSSL: Generate ECC Certificates for Apache Server
Elliptic Curve Cryptography (ECC) is an encryption technique that provides public-key encryption similar to RSA. We can generate ECC certificates using openssl and install it on Apache server for verification
security
Steps to generate CSR for SAN certificate with OpenSSL
Step by step instruction to generate Certificate Signing Request (CSR) for Subject Alternative Name (SAN) certificates using openssl with examples in Linux
security
Revoke certificate and generate CRL OpenSSL [Step-by-Step]
Step by step instructions to revoke or delete certificate from keystone and generate CRL Certificate Revocation List) using openssl in Linux with example openssl generate crl.
security
Create SAN Certificate | OpenSSL generate CSR with SAN command line
Create SAN certificate using openssl generate csr with san command line. Openssl sign CSR with Subject Alternative Name. openssl add san to existing certificate
security
OpenSSL create Client Certificate & Server Certificate with Example
Steps to create client certificate and server certificate using your own Certificate Authority chain (CA bundle) and configure Apache with SSL (HTTPS)
security
Simple Steps to Generate CSR using OpenSSL with Examples
Steps to generate csr (certificate signing request) using openssl in Linux with examples. Create private key with and without passphrase.
security
How to Renew Expired Root CA certificate with OpenSSL
Technically you can't renew expired root CA certificate instead you can create a new root ca certificate using private key with openssl. The new root CA certificate can be used to verify old certificates.
security
Renew SSL/TLS certificate OpenSSL
Step by Step instructions to renew SSL or TLS certificate (server/client) using OpenSSL command. Retain all SAN fields with X.509 extensions during renewal of certificate.
security
Renew self-signed certificate OpenSSL
Step by Step instructions to renew self-signed certificate using OpenSSL command. Export CSR using expired certificate and using existing private key we can renew any kind of certificate
security
Shell script to generate certificate OpenSSL [No Prompts]
Step by Step instructions to use shell script to generate certificates with openssl. generate both self signed and rootCA signed certificates using bash or shell script without any prompt.
security
Things to consider when creating CSR with OpenSSL
We must consider some important point when creating CSR or else we may face issues later while using the certificate
security
How to manually expire any certificate OpenSSL
Step by Step instructions to manually expire any certificate using openssl. Different commands and methods to generate an expired certificate
security
openssl ca vs openssl x509 comparison [With Examples]
Detailed comparison between openssl ca vs openssl x509 command with examples. Similarities and difference between ca vs x509 argument of openssl command
security
How to add X.509 extensions to certificate OpenSSL
Step by Step instructions to add X.509 extensions to certificates, CSR, RootCA using openssl command.
security
Generate duplicate certificates OpenSSL CA [Same CN]
Step by step instructions to generate duplicate certificates with OpenSSL CA using the same CSR with same Subject (Common Name) in all the certificates
security
How to revoke missing/lost certificate OpenSSL [Step-by-Step]
Step by step guide to revoke missing or lost certificate using openssl. We can manually update the CA database to mark any certificate revoked and generate CRL
security
4 step quick guide to install SSL Certificate on Nginx
Install an SSL certificate on Nginx in just 4 steps. Secure your website with HTTPS and gain the trust of your visitors with a valid SSL certificate.
security
How to Install GoBuster with Basic Usage on Ubuntu
This tutorial will guide you through steps to install Gobuster on Ubuntu, configuring it, and basic to advanced usage tips, including working with wordlists and uninstalling if needed.