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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

HTTP/HTTPS
The protocol used for transferring web pages and data between browsers and servers, with HTTPS adding encryption.
HTTPS Everywhere
The practice of securing all web traffic with TLS encryption, ensuring data integrity and privacy between browsers and servers.
Network ACL
A set of rules that control inbound and outbound traffic at the subnet level, acting as a stateless firewall in cloud and enterprise networks.
Reverse Proxy
A server that sits between clients and backend servers, forwarding client requests and returning server responses on their behalf.
Overlay Network
A virtual network built on top of an existing physical network, enabling features like container networking and VPNs.
HTTP Keep-Alive
An HTTP mechanism that reuses a single TCP connection for multiple requests, reducing the overhead of establishing new connections.
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