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Networking Beginner

What is Firewall?

A network security system that monitors and controls incoming and outgoing traffic based on predetermined rules.

Firewalls act as gatekeepers between trusted internal networks and untrusted external networks. They filter traffic based on IP addresses, ports, protocols, and application data.

Types include packet filtering, stateful inspection, proxy, and next-generation firewalls (NGFW). Linux uses iptables or nftables. Common tools include UFW (Ubuntu) and firewalld (RHEL/CentOS).

Related Terms

TCP vs UDP
Two transport layer protocols: TCP provides reliable, ordered delivery while UDP provides fast, connectionless delivery without guarantees.
Port
A numbered endpoint (0-65535) that identifies specific processes or services on a networked computer for communication.
TCP/IP
The fundamental communication protocol suite of the internet that defines how data is packaged, addressed, transmitted, and received.
Overlay Network
A virtual network built on top of an existing physical network, enabling features like container networking and VPNs.
Bandwidth
The maximum rate of data transfer across a network connection, measured in bits per second.
Anycast
A network routing technique where the same IP address is announced from multiple locations, directing users to the nearest server.
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