Network Addresses and Routing

#

• Two machines can communicate on one wire.
• With more machines, there needs to be an address mechanism.
• Circuit switching vs. packet switching
• IPv4 addresses
• LAN, WAN, Subnets and routing
• IPv6 addresses

Layers

#

Web browsing

• Physical (wire / radio)
• Data (ethernet / wifi)
• Network (IP)
• Transport (TCP)
• Security (TLS)
• Application (HTTPS)

Names and DNS

#

• DNS lookups
• DNS cache

TCP

#

• How do we make a reliable stream based protocol using unreliable packets?
• TCP ports
• Rant about WebSockets

TLS

#

• Cryptography
  • Public key
    • Encryption
    • Signatures
  • Secret key
    • Encryption
    • Authentication Codes
• How do we trust a website?
  • The messages are signed, but by who?
  • The certificate is signed, but by who?
  • Certificate authorities
  • Threat model: Great for buying stuff with a credit card, not good enough for very serious threats.
  • Letsencrypt