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…
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Linux sudoers Explained: visudo, wheel Group and Safe NOPASSWD Rules
Understand /etc/sudoers on Linux: use visudo, sudoers.d drop-ins, wheel group, limit commands with Cmnd_Alias, audit auth logs, and…
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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,…
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chmod and chown on Linux: File Permissions, Octal Mode and Ownership
Understand Linux file permissions with ls -l, chmod ugo and 755/644 octal modes, recursive chmod, chown user:group, and…
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Centralise Linux Logs with systemd-journal-remote (Forward and Collect)
Forward systemd journal logs to a central collector with systemd-journal-upload and systemd-journal-remote, secure with HTTPS, and search with…
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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…
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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,…
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SSH Tunneling and Port Forwarding on Linux: -L, -R, -D and ProxyJump
Learn SSH local, remote and dynamic port forwarding, ProxyJump bastion access, persistent tunnels with systemd, and how to…
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PostgreSQL Install and Secure Setup on Linux (Roles, pg_hba.conf, TLS)
Install PostgreSQL on Linux and secure it: roles, listen addresses, pg_hba.conf rules, TLS, baseline tuning, and backup verification.
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Proxmox LXC Security: Unprivileged Containers, ID Mapping and Limits
Harden Proxmox LXC containers: unprivileged mode, UID mapping, safe bind mounts, feature restrictions, firewall and resource limits.
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