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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

DNS over HTTPS (DoH)
A protocol that encrypts DNS queries by sending them over HTTPS, preventing eavesdropping and manipulation of DNS traffic.
Network Segmentation
The practice of dividing a network into isolated segments to improve security, performance, and management.
Overlay Network
A virtual network built on top of an existing physical network, enabling features like container networking and VPNs.
CIDR Notation
A compact method for specifying IP addresses and their associated routing prefix using a slash followed by the prefix length.
IPv6
The latest version of the Internet Protocol with 128-bit addresses, designed to replace IPv4 and solve address exhaustion.
VPN (Virtual Private Network)
A technology that creates an encrypted tunnel between your device and a remote server, securing internet traffic.
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