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 Connectionless 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)