Homelab and Infrastructure

AdGuard Home
AdGuard Home is self-hosted network-wide DNS filtering software that blocks ads, trackers, and certain unwanted domains for every device using your network. It works as a DNS server (often on your router, NAS, VPS, or a small board like a Raspberry Pi) and gives you a web UI to manage filters, logs, and parental controls.
Key facts
Type: Self-hosted DNS sinkhole / DNS filtering software
License: Free and open source (GPL)
Scope: Network-wide (covers all devices using its DNS)
Primary functions: Ad & tracker blocking, parental control, basic security
Deployment targets: Router, Raspberry Pi, server/VPS, many Linux-based systems
Website: AdGuard
How it works
AdGuard Home runs as a DNS resolver on your network. When a device asks for a domain (like 
ads.example.com), AdGuard Home checks the request against its filter lists. If the domain is on a blocklist, it returns a “sinkhole” or invalid address, so the connection to that ad or tracker never happens. If not blocked, it forwards the query to upstream DNS servers you choose (e.g., AdGuard DNS, Cloudflare, etc.).
Features and capabilities
Ad/tracker blocking: Uses filter lists similar to browser ad-blockers (EasyList, AdGuard filters, etc.).
Parental control & safe search: Can block adult content and enforce safe search on major search engines.
Malware & phishing protection: Optional lists to block malicious domains.
Per-client rules: Different devices (kids’ tablets, smart TVs, work laptop) can have different policies.
DNS privacy: Supports encrypted upstream DNS (DoH/DoT/DoQ via compatible resolvers), reducing ISP snooping.
Typical deployment and use cases
Common setups include running AdGuard Home on a home router, on a Raspberry Pi, or in a container on a home server. You then point your router’s DNS to it so every device (phones, laptops, IoT gadgets, TVs) benefits without installing extra apps. It’s often compared with Pi-hole; both are DNS sinkholes with web dashboards, but AdGuard Home leans into a more polished UI and integrated parental-control and DNS-privacy options.
Limitations
Because filtering happens at DNS level, it can’t block everything: same-domain ads (e.g., 
example.com/ads.js), in-app native ads, or some CDN-heavy sites may still show ads. It also doesn’t replace a full firewall or IDS; it’s best seen as a strong first layer of network-wide content and tracking control rather than a complete security solution.

fail2ban
fail2ban is an open-source intrusion prevention software framework written in Python. It protects servers from brute-force attacks by monitoring log files and dynamically banning IP addresses that show malicious signs, such as multiple failed login attempts. Widely used on Linux systems, it serves as a lightweight layer of automated security hardening.
Key facts
Initial release: 2004
Written in: Python
Primary function: Intrusion prevention via log file monitoring
Default ban mechanism: Firewall rules (e.g., iptables, nftables)
License: GNU General Public License v2
How it works
fail2ban scans specified log files for configurable patterns that indicate failed authentication or other suspicious behavior. When such patterns exceed a set threshold, fail2ban triggers an action—commonly inserting a temporary firewall rule that blocks the offending IP address. Once the ban time expires, the rule is automatically removed, restoring normal access.
Configuration and flexibility
fail2ban uses “jails” to define monitoring rules. Each jail combines a log file path, a filter (regular expression pattern), and an action. Administrators can customize thresholds, ban durations, and notification methods. It integrates easily with multiple services, including SSH, FTP, web servers, and mail servers, through predefined jail configurations.
Security impact
The software is valued for reducing exposure to brute-force and credential-stuffing attacks, especially on publicly accessible SSH and web login endpoints. By automatically responding to suspicious activity, fail2ban provides an efficient complement to firewalls and authentication hardening without requiring complex intrusion detection systems.
Ecosystem and community
fail2ban remains under active community maintenance, with repositories hosted on platforms like GitHub. Its modular design has led to wide adoption among system administrators and inclusion in most major Linux distributions’ package repositories. Users frequently share custom filters to adapt the tool for diverse applications and new attack patterns.