This guide explains multiple Linux techniques—setting a user’s shell to /sbin/nologin, editing /etc/passwd, configuring sshd_config with Allow/Deny directives, and using hosts.allow/hosts.deny—to prevent unwanted SSH access for particular users, groups, or IP addresses, and shows how to apply the changes safely.
This guide explains multiple Linux techniques—including nologin shells, sshd_config allow/deny lists, and hosts.allow/hosts.deny rules—to prevent selected users, groups, or IP addresses from logging in via SSH, with practical commands, examples, and a ready‑to‑run script.
This article explains how a Raspberry Pi exposed to the Internet was repeatedly attacked via SSH, how the author identified the brute‑force attempts in /var/log/auth.log, and step‑by‑step methods using hosts.allow/deny and ufw to whitelist trusted IPs and block malicious traffic.
This guide explains three practical methods—modifying sqlnet.ora, configuring /etc/hosts.deny and /etc/hosts.allow, and applying iptables rules—to allow only specific IP addresses or subnets to connect to an Oracle 11g database and its SSH service on a CentOS server.
