Introduction to IP

The first steps from “Breaking into InfoSec” is to learn or at least catch up on Network Fundamentals. While I worked as a network admin for a couple years, it was with a smaller company and there are things you learn on the job and then there are things that you just didn’t need to learn to keep the network going. With the coming videos, I’ll dive into the easy.. IP information to the, probably not hard but I’ve always ignored the OSI model, why? who knows. but here I go.

The first video is Introduction to IP

Most of this was refreasher for me but there were some take-aways and deeper information that I thought was worth taking note of.

TCP/UDP Multiplexing
     Use many differnet applications at the same time
     TCP = Transmission Control Protocol
     TCP numbers packets
     Receiving device can slowdown transmissio

UDP = User Datagram Protocal
Sender determines transmission speed

Non-ephemeral ports = Permanent port numbers
    Ports 0 through 1023
    On a server or service

Ephemeral Ports = Temp port numbers
    Ports 1024 through 65,535
    Usually determined by client (real time), could be random

Port numbers are for communication, not security

UDP :80 and TCP:80 are different ports
    Not conflict

Most applications have well know ports
    Webservices tcp/80
    Voip udp/5004
    Email server tcp/143

ICMP = Internet Control Message Protocol
    Checkin for devices
    Not for data transfer
    Checks on a device
    Devices can also send ICMP message
    (like time to live has expired)