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 guide explains how to secure Linux servers by configuring sshd to allow or deny specific users or IPs, using hosts.allow/hosts.deny for IP filtering, and setting up iptables rules to open only required ports while blocking all others.
Learn why SSH connections drop due to TCP timeout settings and follow step‑by‑step Linux, Windows (PuTTY), and server‑side configurations—including tcp_keepalive and ServerAlive options—to keep remote sessions active and avoid idle‑disconnects for developers.
This guide explains why the default SSH configuration on Linux is risky and provides eight concrete hardening measures—including disabling root login, changing the default port, enforcing key‑based authentication, limiting login attempts, and restricting access by IP—to secure your server against common attacks.
This guide explains why allowing root SSH access is risky, shows how to edit the sshd_config file to set PermitRootLogin no, restart the SSH service, verify the restriction, and optionally allow specific users or re‑enable root login when needed.
