You think you know the Internet

Original:

Internet Control Message Protocol

RFC 792, Year: 1981

Now: ICMPv4

ICMP Echo Request

ICMP Echo Reply

Request for Comment

Standardization process of the Internet Engineering Task Force (IETF)

four octets (0-255)

0 on Windowssystems is loopback

:: expands to all 0000

2a02::1.2.3.4: octets are converted to hex 2a02::0102:3ff

simplified URL syntax: protocol://host:port/path

free and open source CLI app for uploading and downloading individual files

addresses (automatically assigned by the client) valid on the current LAN

needs zoneid if system has multiple networkinterfaces

via “stateless autoconfiguration” or via DHCPv6

Client socket —> Server socket

client:connect —> server:listen

ports <1024 are priviliged

I can listen to a port 0 but not connect: Port 0 asks the kernel to dynamically assign a free port

2^16

A UDP|TCP connection is an “agreement” between two parties, uniquely

identified by a four-tuple

– Client IP

– Client port

– Server IP

– Server port

Maximum Transmission Unit

Ethernet’s MTU is generally 1500 octets (9000 for jumbo frames)

1492 for DSL, 1480 for PPPoE

used to securely identify servers and to establish encrypted connections between services and clients

Domain Name System

Want to lookup “.at”, but prefix . is not allowed?

Use “at.”

The Domain Name System (DNS) is a hierarchical and distributed name service that provides a naming system for computers, services, and other resources on the Internet or other Internet Protocol (IP) networks.