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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

MTU (Maximum Transmission Unit)
The maximum size of a data packet that can be transmitted over a network without fragmentation.
Port
A numbered endpoint (0-65535) that identifies specific processes or services on a networked computer for communication.
Reverse Proxy
A server that sits between clients and backend servers, forwarding client requests and returning server responses on their behalf.
IP Address
A unique numerical label assigned to each device on a computer network for identification and communication.
Traceroute
A network diagnostic tool that shows the path packets take from source to destination, listing each hop along the way.
OSI Model
The seven-layer Open Systems Interconnection model that standardizes network communication functions from physical transmission to application protocols.
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