Networking Fundamentals

IP Address

Identifies a device or interface on a network.

Private IP Ranges

10.0.0.0/8
172.16.0.0/12
192.168.0.0/16

Subnet

A subnet defines a range of IP addresses. One IP is reserved as the network IP and the other is the broadcast address.

CIDR Notation

Defines how many bits belong to the network portion.

TCP

Connection-oriented and uses a three-way handshake with syn, syn-ack, and a final ack.

UDP

Connectionless, does not guarantee delivery , used by DNS, and streaming.

Ports

Identify services on a host.

DNS

Translates names into IP addresses.

DHCP

Automatically assigns IP configuration to hosts such as IP address, gateway, DNS server, and lease time.

IPAM

Used to track and manage IP address allocation.

Routing

Determines where packets go next.

NAT

Changes source or destination IP addresses between private and public networks.

Stateless Firewall

Evaluates each packet independently and does not track the connection state. Rules need to be more specific.Stat

Stateful Firewall

Track connection state, if an outbound connection is allowed, then return traffic is also automatically allowed.

Implicit Deny

Firewall will deny traffic by default if no allow rule matches, but it also means that missing rules can break application rules.