nc (netcat) on Linux: Test Open Ports and Simple TCP Debugging
Use nc netcat on Linux to test if a port is open: nc -zv host port, listen with…
Read tutorial →firewall
Browse step-by-step tutorials in this topic.
SSH Connection Refused on Linux: Fix Port, sshd, Firewall and SELinux
Fix SSH connection refused: verify sshd is running and listening, correct Port in sshd_config, UFW/firewalld and cloud security…
Read tutorial →
firewalld on Linux: Zones, Services, Ports and Permanent Rules (RHEL/Alma)
Configure firewalld on AlmaLinux/Rocky: install, zones, allow http/https/ssh, custom ports, --permanent rules, reload, and verify with firewall-cmd and…
Read tutorial →
nftables on Linux: Basic Firewall Rules (SSH, HTTP/HTTPS) That Persist
Set up nftables on Linux: tables, chains, default drop, allow SSH and web ports, persist ruleset to /etc/nftables.conf,…
Read tutorial →
Fail2ban Nginx Jail: Block Abusive IPs (HTTP 404/401 floods and scanners)
Configure Fail2ban jails for Nginx: install filters for 404/401 abuse and bad bots, set findtime and bantime, test…
Read tutorial →
Install and Secure Redis on Linux (bind, AUTH, firewall, TLS basics)
Install Redis on Linux, bind to localhost or a private interface, set requirepass and ACLs, firewall port 6379,…
Read tutorial →
WireGuard VPN Server Setup on Linux (Step-by-Step Guide)
Build a WireGuard VPN server on Linux: keys, wg0.conf, NAT and firewall rules, client configs, and peer management.
Read tutorial →
nftables Firewall Basics on Linux (Replace iptables)
Configure nftables firewall on Rocky Linux, AlmaLinux, and Fedora. Allow SSH and web ports with a simple ruleset.
Read tutorial →
iptables Firewall Backup & Restore Shell Script for Linux
Backup and restore iptables firewall rules on Linux with a Bash script. Save rules before updates or reboots.
Read tutorial →
UFW Firewall Basics: Secure Your Linux Server
Configure UFW firewall on Ubuntu and Debian. Allow SSH, HTTP, HTTPS and block unwanted traffic.
Read tutorial →