Firewall

A firewall is a network component — implemented as hardware or software — that inspects and filters network traffic according to configured rules. For Audio/Video, Maker and Web projects it protects streaming/media servers, IoT and maker devices (e.g., Raspberry Pi) and web applications from unauthorized access and certain kinds of attacks. Firewalls operate at different levels: host-based (on a single device), network-based (between networks) and specialized web application firewalls (WAFs) that filter at the application layer. Key concepts include rules for ports and protocols, stateful versus stateless filtering, NAT/port-forwarding and the trade-off between security and accessibility — overly strict rules can block legitimate media streams or device communications.

Example: you run a live stream from a studio using a local RTMP server on a machine inside your network. The network firewall must be configured to allow the RTMP port (e.g., 1935) to reach the streaming server while blocking other unwanted ports. At the same time, a maker builds a smart sensor on a Raspberry Pi that communicates to a cloud server over SSH and MQTT — on that device you enable a host-based firewall (e.g., iptables or ufw) to allow only SSH and MQTT ports and deny other incoming connections. For a web project you place a WAF or reverse proxy in front of the web server to block common web attacks while keeping specific API ports open for the frontend. Testing with tools like nmap and reviewing firewall logs helps ensure media streams and device communications aren’t accidentally blocked.