Find SUID SGID Binaries Shell Script (Linux Security Audit)
Audit SUID and SGID files on Linux with a Bash script: find / -perm, compare to baseline, alert…
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ssh-copy-id on Linux: Passwordless SSH Login (ed25519 Keys)
Set up passwordless SSH with ssh-copy-id: generate ed25519 keys, copy pubkey to remote authorized_keys, test login, and harden…
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umask on Linux: Default File Permissions Explained (022, 027, sftp)
Understand umask on Linux: how 022 and 027 change new file and directory modes, set umask in shell…
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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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