Security
Security hardening, SSH protection, firewalling, access control, and auditing tools.
How to List and Delete UFW Firewall Rules
Learn how to list active UFW rules, then delete them by number or specification. Includes status verbose, numbered output, rule reset, and SSH lockout recovery.
How to Set Up Passwordless SSH Login
Set up passwordless SSH login with Ed25519 or RSA key pairs. Copy public keys with ssh-copy-id, use the ssh-agent, and disable password authentication for hardened access.
How to Change User Password in Ubuntu
Change a user password in Ubuntu from the command line with passwd, or through the GNOME Settings app. Covers your own account and other users.
How to Generate SSH Keys on Linux with ssh-keygen
Learn how to generate SSH keys on Linux using ssh-keygen, copy them to remote servers, and set up passwordless authentication.
SSH SOCKS Proxy: Create a SOCKS5 Tunnel for Browsing
Create an SSH SOCKS proxy with a SOCKS5 tunnel, configure Firefox or Chrome to use it, proxy DNS requests, and verify the browser exits through your SSH server.
SSH Hardening Guide: Best Practices for Linux Servers
SSH hardening best practices for Linux servers, including sshd_config checks, key-only logins, root login restrictions, firewall rules, timeouts, and Fail2Ban.
Initial Server Setup on Ubuntu 26.04
Prepare a new Ubuntu 26.04 server with a sudo user, SSH key authentication, UFW firewall rules, a hostname, timezone settings, and system updates.
su Command in Linux: Switch User
The su command in Linux switches users in the current session and runs commands with another user's privileges. Examples, options, and a sudo vs su comparison.
What Does chmod 777 Mean
chmod 777 gives every user on the system full access to a file or directory. This guide explains what 777 means, how Linux permission numbers work, and what to use instead.
How to Change the SSH Port in Linux
Change the default SSH port 22 by editing sshd_config, adjusting the firewall, and reloading the SSH service on Linux.
SSH Tunnel: Local, Remote, and Dynamic Port Forwarding
SSH tunneling (port forwarding) encrypts and relays TCP traffic through a secure SSH connection. This guide covers local, remote, and dynamic port forwarding with practical examples.
ufw Command in Linux: Uncomplicated Firewall Reference
Reference for the ufw command on Linux, with examples for enabling the firewall, allowing and denying traffic, deleting rules, and managing application profiles.
passwd Command in Linux: Change User Passwords
Use the passwd command to change your own or another user's password in Linux. Covers root password changes, password expiry with chage, and account locking.
How to Set Up a Firewall with UFW on Ubuntu 24.04
Step-by-step instructions for configuring and managing a UFW firewall on Ubuntu 24.04. UFW is a user-friendly front-end for managing iptables firewall rules.
How to Create a Self-Signed SSL Certificate with OpenSSL
Generate a self-signed SSL/TLS certificate and private key on Linux using the openssl command. Covers RSA and ECDSA keys, Subject Alternative Names (SAN), and non-interactive generation.
How to Enable and Disable Root User Account in Ubuntu
This guide explains how to enable and disable the root user account in Ubuntu using the passwd command, and covers safer alternatives like sudo -i and su -.
How to Set Up SFTP Chroot Jail
Step-by-step instructions for setting up an SFTP Chroot Jail on Linux to restrict users to their home directories using OpenSSH.
