Time Sensitive Application Data loss Bandwidth - - PDF document

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Oct 24, 2022 101 likes •181 views

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SLIDE 1

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✑✓✒✕✔✗✖✙✘✛✚✢✜✤✣✗✥✙✔✧✦

★✗✩ ✪ ✫✭✬✯✮✰✫☎✱✯✲✴✳✭✵✰✶✯✷✴✸ ✹ ✺ ✲✯✷ ✱ ✺ ✱✌✮☎✳ ✶✴✳ ✹ ✬✯✮✻✶✰✼✴✲✰✱✯✫✰✳ ✼ ✬✴✽✾✮✭✱✛✳✭✿✕✬✛❀✰❁✻✶✛✲✴✲✯✷ ✹ ✫✭✶✴✳ ✹ ✬✯✮ ✲❂❀ ✬✛✳ ✬✛✫✭✬✌✷ ✼ ❃ ✫❂✷ ✹ ✱✌✮☎✳✓✼☎✱✯❀✭❄✭✱✌❀ ✲✰✶❂❀ ✶❂❅ ✹ ❆❂✺ ❃ ✼☎✱✯❀✭❄ ✹ ✫✭✱ ✺ ✬✛❅❂✱✗✷ ✼ ✪ ✷ ✱❂✶✛❀✰✮✓✶✯❇✴✬❂✵✴✳❈✲✴❀ ✬❂✳ ✬✛✫☎✬✌✷ ✼❉❇❂❊ ✱✛❋✯✶ ✺●✹ ✮ ✹ ✮ ❆ ✲☎✬✯✲✰✵✯✷ ✶❂❀ ✶❂✲❂✲✯✷ ✹ ✫☎✶✴✳ ✹ ✬✯✮✰❍✭✷ ✱✛❄✭✱✙✷ ✲❂❀ ✬✛✳ ✬✛✫✭✬✌✷ ✼ ■ ✥✗✜❂✚❑❏✗✒✕✔✙✖✙✘✛✚✢✜✤✣✕✥✌✔✢✦ ★ ▲ ★✌✖✙✚✧❏✕▼ ◆✧▼ ❏❖✖✕✜✛✥✙✘✯✥✙❏✙✥✧✦ ★✗✩ ❃ P ✳✭✳☎✲ ❃ ✽✴✳☎✲ ❃ ✼ ✺ ✳☎✲ ❃ ✲✰✬✛✲ ❃ ❅✌✮✭✼ ▲ ✖✕✜✛✥✌✣✧✜❂✔✙◗❘◗❖▼ ❙✛✣❚❙✯✚✕✘✛❯❉✥✗✜✯❱ ✔✗✖✗✖✢✦ ▼ ❏✌✔✙✘✙▼ ✥✧❙✛★ ❃ ✼☎✬✛✫❂❁✭✱✯✳✻✲❂❀ ✬ ❆ ❀ ✶ ✺✻✺●✹ ✮ ❆

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

❲❚❳❨❳❈❩ ❬ ❭✧❪❴❫❨❬ ❵❈❛✧❜❝❪✻❛✧❞❡❪✻❳❨❳❈❩ ❬ ❭✧❪❴❫❨❬ ❵❈❛❴❢✗❩ ❪✧❣✓❤❉✐❝❳❨✐✙❵❨❫✧❵✻❭✧❵❉❩ ❜ ❥ ✲✴✲✯✷ ✹ ✫✭✶✴✳ ✹ ✬✯✮❂❦✛✫☎✬ ✺✓✺ ✵✛✮ ✹ ✫✭✶✴✳ ✹ ✮ ❆✯❧ ❅ ✹ ✼✰✳☎❀ ✹ ❇✛✵✴✳ ✱✯❅✤✲✴❀ ✬✛✫☎✱❂✼☎✼☎✱✛✼ ❃ ❀✭✵✛✮✴✮ ✹ ✮ ❆✤✹ ✮❉✮✭✱✛✳✭✿✧✬✛❀☎❁ P ✬✴✼✰✳ ✼ ✹ ✮ ♠ ✵✰✼☎✱✯❀✓✼✴✲☎✶✛✫✭✱✯♥ ❃ ✱✛❋✙✫ P ✶✛✮ ❆ ✱ ✺ ✱❂✼✰✼☎✶ ❆ ✱✛✼❈✳ ✬ ✹ ✺ ✲✯✷ ✱ ✺ ✱✌✮☎✳❨✶✛✲❂✲ ❃ ✱✌♦ ❆ ♦ ❧ ✱ ✺ ✶ ✹ ✷ ❧ ✽ ✹ ✷ ✱✾✳☎❀ ✶✯✮✭✼☎✽✰✱✯❀ ❧ ✳ P ✱✤♣q✱✌❇ ❥ ✲✴✲✯✷ ✹ ✫✭✶✴✳ ✹ ✬✯✮✰❍✭✷ ✶✰❊✴✱✯❀❈✲✴❀ ✬❂✳ ✬✛✫☎✬✌✷ ✼ ❃ ✬✯✮✭✱ ♠ ✲ ✹ ✱✌✫✭✱✛♥✧✬✴✽●✶✛✮✻✶❂✲❂✲ ❃ ❅❂✱✛✽ ✹ ✮✭✱ ✺ ✱❂✼☎✼☎✶ ❆ ✱✛✼ ✱✛❋✙✫ P ✶✛✮ ❆ ✱✌❅✤❇❂❊●✶✛✲✴✲✰✼❈✶✛✮✰❅ ✶❂✫✰✳ ✹ ✬✯✮☎✼❈✳ ✶✯❁✭✱✙✮ ❃ ✵✰✼☎✱✯❀❨✼✰✱✯❀✭❄ ✹ ✫☎✱❂✼❉✲✴❀ ✬❂❄ ✹ ❅❂✱✯❅r❇❂❊ ✷ ✬❂✿✕✱✌❀●✷ ✶✰❊✴✱✯❀❈✲✴❀ ✬❂✳ ✬✛✫☎✬✌✷ ✼ s t t ✉ ✈ ✇ s ① ✈ ② ③ ① ④ s ③ ⑤ t ② ④ ① ③ ⑥ ① ⑦ ② ④ ⑧ ⑨ s ① s ✉ ✈ ③ ⑧ t ⑩ ❶ ⑤ ✈ ✇ s ✉ s t t ✉ ✈ ✇ s ① ✈ ② ③ ① ④ s ③ ⑤ t ② ④ ① ③ ⑥ ① ⑦ ② ④ ⑧ ⑨ s ① s ✉ ✈ ③ ⑧ t ⑩ ❶ ⑤ ✈ ✇ s ✉ s t t ✉ ✈ ✇ s ① ✈ ② ③ ① ④ s ③ ⑤ t ② ④ ① ③ ⑥ ① ⑦ ② ④ ⑧ ⑨ s ① s ✉ ✈ ③ ⑧ t ⑩ ❶ ⑤ ✈ ✇ s ✉

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

❷ ❩ ❬ ❤❸❛✧❫✢❢❂❜✕❤●✐✗❹✕❤❉✐❝❳✢❪✓✐✗❪❨❞✾❬ ❺❈❻ ❼ ❊✛✲ ✹ ✫✭✶✌✷❂✮✭✱✯✳✭✿✕✬✛❀✰❁✻✶❂✲❂✲ P ✶✰✼●✳✭✿✕✬ ✲ ✹ ✱✌✫✭✱❂✼✛❦ ❽✴❾ ❿ ➀✯➁✗➂ ✶✯✮✰❅ ➃❂➀❂➄✙➅ ➀❂➄ s t t ✉ ✈ ✇ s ① ✈ ② ③ ① ④ s ③ ⑤ t ② ④ ① ③ ⑥ ① ⑦ ② ④ ⑧ ⑨ s ① s ✉ ✈ ③ ⑧ t ⑩ ❶ ⑤ ✈ ✇ s ✉ s t t ✉ ✈ ✇ s ① ✈ ② ③ ① ④ s ③ ⑤ t ② ④ ① ③ ⑥ ① ⑦ ② ④ ⑧ ⑨ s ① s ✉ ✈ ③ ⑧ t ⑩ ❶ ⑤ ✈ ✇ s ✉ ➆ ✷ ✹ ✱✌✮☎✳✴❦ ✪ ✹ ✮ ✹ ✳ ✹ ✶✴✳ ✱✛✼●✫✭✬✌✮☎✳ ✶❂✫✰✳✓✿ ✹ ✳ P ✼☎✱✯❀✭❄✭✱✌❀ ➇ ♠ ✼✴✲✰✱❂✶✯❁✭✼❈✽ ✹ ❀ ✼✴✳✭♥ ➈ ✪ ✳ ❊✛✲ ✹ ✫✭✶✌✷ ✷ ❊❸❀ ✱✛➉✴✵✰✱❂✼✰✳ ✼❈✼☎✱✯❀✭❄ ✹ ✫✭✱❸✽❂❀ ✬ ✺ ✼☎✱✯❀✭❄✭✱✌❀ ❧ ✪ ✱✌♦ ❆ ♦ ❦✛❀ ✱✛➉✴✵✰✱❂✼✰✳❈♣❑♣❚♣➊✲☎✶ ❆ ✱ ❧ ✼☎✱✙✮✰❅ ✱ ✺ ✶ ✹ ✷ ➋ ✱✯❀✭❄✭✱✯❀✴❦ ✪ ✲❂❀ ✬✛❄ ✹ ❅❂✱✛✼●❀ ✱✛➉✴✵✰✱❂✼✰✳ ✱✌❅❉✼✰✱✯❀✭❄ ✹ ✫☎✱❸✳✭✬ ✫❂✷ ✹ ✱✌✮☎✳ ✪ ✱✌♦ ❆ ♦ ❧ ✼☎✱✙✮✰❅❂✼●❀ ✱✛➉✴✵✰✱❂✼✰✳✭✱✯❅✤♣❑♣❑♣ ✲✰✶ ❆ ✱ ❧ ❀ ✱✌✫✭✱ ✹ ❄✭✱❂✼✰➌✰✼✰✳ ✬✛❀ ✱❂✼❉❀ ✱✌✫✭✱ ✹ ❄✭✱✯❅ ✱ ✺ ✶ ✹ ✷ ❀ ✱✛➉✴✵✰✱❂✼✰✳ ❀ ✱✯✲✯✷ ❊

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

➍❸➎✌➏

✩✗✔✙✖✗✖❴✦ ▼ ❏✌✔✙✘✌▼ ✥✕❙ ✖✕✜✛✥✌✣✧✜❂✔✙◗❘◗❖▼ ❙✛✣❚▼ ❙✛✘✛✚✢✜❂◆✌✔✗❏✌✚ ▲ ➐ ✚✕◆✧▼ ❙✯✚✗★➑▼ ❙✯✘✛✚✧✜❂◆✙✔✙❏✌✚ ➒ ✚✕✘❂❯❉✚✗✚❴❙❘✔✗✖✗✖✢✦ ▼ ❏✌✔✙✘✙▼ ✥✧❙ ✔✧❙ ➐ ✘✌✜✴✔✧❙✛★✌✖✕✥✗✜❂✘q✦ ✔✯➓✕✚✢✜ ▲ ★✌✥✙❏✗❱✙✚✕✘✗✩ ➏ ❙✯✘✛✚✧✜✌❙✯✚✗✘ ➍❸➎✌➏ ❃ ✳✭✿✕✬✾✲✴❀ ✬✛✫☎✱❂✼☎✼☎✱✛✼ ✫✭✬ ✺✻✺ ✵✛✮ ✹ ✫✭✶✴✳ ✱r❇❂❊●✼☎✱✌✮✴❅ ✹ ✮ ❆ ❅❂✶❂✳ ✶ ✹ ✮☎✳ ✬❉✼☎✬✛✫✴❁☎✱✛✳ ❧ ❀ ✱❂✶✛❅ ✹ ✮ ❆ ❅❂✶❂✳ ✶●✬❂✵✴✳❨✬✴✽ ✼☎✬✛✫❂❁✭✱✯✳ ➔ ✩ ✒✧✥✌❯ ➐ ✥✌✚✕★→✔❖✖✧✜❂✥✗❏✌✚✗★✯★ ➣ ▼ ➐ ✚❴❙✯✘✙▼ ◆✛➓❴↔✻✘✌✒✕✚❑✥✙✘✌✒✕✚✧✜ ✖✕✜✛✥✙❏✌✚✕★✯★❘❯✾▼ ✘✌✒➑❯❸✒❴▼ ❏✗✒↕▼ ✘ ❯●✔✧❙✛✘✛★→✘✛✥q❏✙✥✗◗❘◗❘➙✕❙✙▼ ❏✌✔✌✘✛✚✕➛ ❃ ➜✯➝ ✶✛❅✯❅✯❀ ✱❂✼☎✼ ✬✴✽ P ✬✴✼✰✳ ❀✭✵✛✮✴✮ ✹ ✮ ❆ ✬❂✳ P ✱✯❀✻✲❂❀ ✬✛✫✭✱✛✼☎✼ ❃ ♠ ✲✰✬✛❀✭✳❈✮☎✵ ✺ ❇❂✱✯❀ ♥❴❍✧✶✯✷ ✷ ✬❂✿✕✼ ❀ ✱✯✫☎✱ ✹ ❄ ✹ ✮ ❆ P ✬✴✼✴✳✓✳ ✬ ❅❂✱✯✳ ✱✯❀ ✺●✹ ✮✭✱✾✳ ✬❸✿ P ✹ ✫ P ✷ ✬✛✫☎✶✯✷❂✲✴❀ ✬✛✫☎✱❂✼☎✼●✳ P ✱ ✺ ✱❂✼☎✼☎✶ ❆ ✱❸✼ P ✬❂✵✯✷ ❅✤❇❂✱ ❅❂✱✗✷ ✹ ❄✭✱✌❀ ✱✌❅ ➞ ✦ ✥✙✘✛★→◗❘✥✕✜✴✚❑✥✧❙❘✘✌✒✢▼ ★➑✦ ✔✙✘✛✚✧✜✯➟

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✔✌✘✛✔❚✦ ✥✙★✯★ ✪ ✼☎✬ ✺ ✱❸✶❂✲❂✲✰✼ ➇ ✱✙♦ ❆ ♦ ❧ ✶❂✵✴❅ ✹ ✬✛➈✧✫✭✶✛✮ ✳ ✬✌✷ ✱✌❀ ✶❂✳ ✱❸✼☎✬ ✺ ✱❘✷ ✬✴✼☎✼ ✪ ✬❂✳ P ✱✯❀❨✶✛✲✴✲✰✼ ➇ ✱✌♦ ❆ ♦ ❧ ✽ ✹ ✷ ✱ ✳☎❀ ✶✛✮✭✼☎✽✴✱✯❀ ❧ ✳ ✱✗✷ ✮✭✱✛✳☎➈✧❀ ✱✛➉✴✵ ✹ ❀ ✱ ➡ ➢✙➢✗➤ ❀ ✱✙✷ ✹ ✶✛❇✙✷ ✱✤❅❂✶✴✳ ✶❉✳☎❀ ✶✯✮✭✼☎✽✰✱✯❀ ➥ ▼ ◗❖▼ ❙✛✣ ✪ ✼☎✬ ✺ ✱❸✶❂✲❂✲✰✼ ➇ ✱✙♦ ❆ ♦ ❧ ➜ ✮☎✳ ✱✌❀✰✮✭✱✛✳ ✳ ✱✙✷ ✱✯✲ P ✬✯✮✭❊ ❧✯✹ ✮☎✳ ✱✌❀ ✶✛✫☎✳ ✹ ❄✭✱ ❆ ✶ ✺ ✱❂✼✴➈✧❀ ✱✯➉✰✵ ✹ ❀ ✱❘✷ ✬❂✿➑❅❂✱✗✷ ✶✰❊❉✳ ✬ ❇❂✱ ♠ ✱❂✽✰✽✰✱✯✫✰✳ ✹ ❄☎✱✛♥ ➦ ✔✧❙ ➐ ❯✤▼ ➐ ✘✌✒ ✪ ✼☎✬ ✺ ✱❸✶❂✲❂✲✰✼ ➇ ✱✙♦ ❆ ♦ ❧✴✺ ✵✯✷ ✳ ✹ ✺ ✱✯❅ ✹ ✶❂➈ ❀ ✱✛➉✴✵ ✹ ❀ ✱ ✺●✹ ✮ ✹ ✺ ✵ ✺ ✶ ✺ ✬❂✵✛✮☎✳❨✬✴✽ ❇❂✶✛✮✰❅✛✿ ✹ ❅✛✳ P ✳ ✬✤❇❂✱ ♠ ✱❂✽✰✽✰✱✯✫✰✳ ✹ ❄☎✱✛♥ ✪ ✬❂✳ P ✱✯❀❨✶✛✲✴✲✰✼ ➇ ♠ ✱✙✷ ✶✴✼✰✳ ✹ ✫✓✶✛✲❂✲☎✼✰♥ ➈ ✺ ✶✛❁☎✱✾✵✰✼☎✱❉✬✴✽❉✿ P ✶✴✳ ✱✯❄✭✱✯❀ ❇❂✶✛✮✰❅✛✿ ✹ ❅✛✳ P ✳ P ✱❂❊ ❆ ✱✛✳

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

➧ ✐✗❪✻❛✕❜❨❳✢❵✻✐✗❫➨❜✕❤●✐✗❹✓❬ ❭✕❤➩✐✌❤❈➫❨➭❈❬ ✐✙❤●❻❑❤❸❛✧❫✕❜➨❵✓➯➲❭✧❵✻❻➨❻❚❵❈❛➨❪✻❳✓❳✧❜

Application file transfer e-mail Web documents real-time audio/video stored audio/video interactive games financial apps Data loss no loss no loss loss-tolerant loss-tolerant loss-tolerant loss-tolerant no loss Bandwidth elastic elastic elastic audio: 5Kb-1Mb video:10Kb-5Mb same as above few Kbps up elastic Time Sensitive no no no yes, 100’s msec yes, few secs yes, 100’s msec yes and no

SLIDE 2

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✑ ➎ ★✯✚✢✜✁✗▼ ❏✌✚❴✩ ✪ ❽✄✂❂➁✴➁✴➀✯❽✌➂ ❿ ✂❂➁✆☎ ✂✴➄✰❿ ➀✛➁✗➂ ➀✞✝✠✟ ✼☎✱✛✳✭✵❂✲ ❀ ✱✛➉✴✵ ✹ ❀ ✱✯❅r❇✴✱✯✳✭✿✕✱❂✱✙✮❈✫✛✷ ✹ ✱✙✮☎✳ ❧ ✼☎✱✯❀✭❄✭✱✌❀ ✪ ➄☎➀✯❾ ❿ ✡✁☛✙❾ ➀q➂ ➄☞✡✴➁✭➃✄✌✞✂✴➄✙➂ ❇❂✱✛✳✭✿✕✱✛✱✌✮ ✼☎✱✌✮✰❅ ✹ ✮ ❆ ✶✛✮✴❅✾❀ ✱✯✫☎✱ ✹ ❄ ✹ ✮ ❆ ✲❂❀ ✬✛✫✭✱❂✼☎✼ ✪✎✍✭❾ ✂✆✏❖❽✄✂❂➁✗➂ ➄☞✂✛❾ ✟ ✼☎✱✙✮✰❅❂✱✯❀✻✿✕✬✯✮☞✑ ✳ ✬❂❄✭✱✯❀✭✿ P ✱✙✷ ✺ ❀ ✱✯✫✭✱ ✹ ❄✭✱✌❀ ✪ ❽✄✂❂➁ ✒✙➀✰➃✕➂ ❿ ✂❂➁❉❽☞✂❂➁✗➂ ➄☞✂✛❾ ✟ ✳ P ❀ ✬❂✳✭✳✴✷ ✱ ✼☎✱✌✮✰❅✛✱✯❀✓✿ P ✱✌✮❉✮✭✱✛✳✭✿✕✬✯❀☎❁ ✬❂❄✭✱✯❀✴✷ ✬✴✶✛❅❂✱✯❅ ✪✓✝✔✂✴➀✴➃❉➁✕✂✕➂✆✌✌➄✄✂✕➅ ❿ ✝✯❿ ➁ ✒✖✟ ✳ ✹ ✺●✹ ✮ ❆✌❧ ✺●✹ ✮ ✹ ✺ ✵ ✺ ❇❂✶✛✮✰❅✛✿ ✹ ❅✛✳ P ❆ ✵✰✶❂❀ ✶✯✮☎✳ ✱❂✱✛✼ ✗✤➠ ➎ ★✯✚✧✜✔✗▼ ❏✌✚❨✩ ✪ ✵✛✮✰❀ ✱✙✷ ✹ ✶✛❇✙✷ ✱✾❅✛✶✴✳ ✶❉✳☎❀ ✶✛✮☎✼☎✽✰✱✯❀ ❇❂✱✛✳✭✿✕✱❂✱✙✮✓✼☎✱✙✮✰❅ ✹ ✮ ❆ ✶✯✮✰❅ ❀ ✱✯✫☎✱ ✹ ❄ ✹ ✮ ❆ ✲✴❀ ✬✛✫☎✱❂✼☎✼ ✪ ❅❂✬✴✱✛✼❉✮✭✬❂✳❈✲❂❀ ✬❂❄ ✹ ❅❂✱✗❦ ✫✭✬✯✮✴✮☎✱✯✫☎✳ ✹ ✬✯✮✓✼✰✱✛✳✭✵❂✲ ❧ ❀ ✱✙✷ ✹ ✶✛❇ ✹ ✷ ✹ ✳ ❊ ❧ ✽✯✷ ✬❂✿q✫☎✬✯✮☎✳☎❀ ✬✌✷ ❧ ✫✭✬✯✮ ❆ ✱❂✼✰✳ ✹ ✬✯✮❈✫☎✬✯✮☎✳☎❀ ✬✌✷ ❧ ✳ ✹ ✺●✹ ✮ ❆✯❧ ✬✛❀❈❇❂✶✛✮✰❅✯✿ ✹ ❅✛✳ P ❆ ✵✰✶❂❀ ✶✛✮☎✳ ✱✛✱ ✘ ❦ ✿ P ❊✾❇✴✬❂✳ P ✱✌❀ ✙ ♣ P ❊ ✹ ✼ ✳ P ✱✯❀ ✱❸✶✛✚✢✜ ➝ ✙

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✣ ❛✧❫✗❤❉✐✧❛✕❤❈❫↕❪✻❳✓❳✢❜✢✤✓❫✦✥❨❤❸❬ ✐ ❳❴✐✗❵❨❫✕❵✻❭✧❵❉❩ ❜❝❪✻❛✧❞ ❫✢✐✗❪✻❛✧❜❨❳✢❵✻✐✙❫ ❳❨✐✙❵❨❫✧❵✻❭✧❵❉❩ ❜

Application e-mail remote terminal access Web file transfer streaming multimedia remote file server Internet telephony Application layer protocol smtp [RFC 821] telnet [RFC 854] http [RFC 2068] ftp [RFC 959] proprietary (e.g. RealNetworks) NSF proprietary (e.g., Vocaltec) Underlying transport protocol TCP TCP TCP TCP TCP or UDP TCP or UDP typically UDP

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✒✕✘✛✘✯✖✢✩✧✒✌➓✧✖✗✚✧✜❂✘✛✚★✧✢✘❘✘✌✜✴✔✧❙✛★✯◆✙✚✧✜

✖✕✜✛✥✌✘✯✥✗❏✙✥✧✦ ✪ ♣❑♣❚♣✩✑ ✼✻✶✛✲✴✲✯✷ ✹ ✫✭✶✴✳ ✹ ✬✯✮❸✷ ✶✰❊✴✱✯❀ ✲❂❀ ✬✛✳ ✬✛✫✭✬✌✷ ✪ ✫❂✷ ✹ ✱✌✮☎✳☎➌☎✼☎✱✯❀✭❄✭✱✌❀ ✺ ✬✛❅❂✱✙✷ ❃ ❽✰❾ ❿ ➀✛➁✗➂ ✟ ❇✯❀ ✬❂✿✕✼☎✱✯❀✻✳ P ✶❂✳ ❀ ✱✛➉✴✵✰✱❂✼✰✳ ✼ ❧ ❀ ✱✯✫✭✱ ✹ ❄✭✱✛✼ ❧ ♠ ❅ ✹ ✼✴✲✯✷ ✶✰❊✴✼✰♥❴♣❑♣❚♣ ✬✯❇✔✪ ✱✯✫☎✳ ✼ ❃ ➃✴➀❂➄✙➅ ➀✛➄✔✟ ♣❚♣❑♣ ✼☎✱✌❀ ❄✭✱✌❀ ✼☎✱✌✮✰❅✛✼✻✬✯❇✔✪ ✱✯✫✰✳ ✼ ✹ ✮ ❀ ✱❂✼✴✲✰✬✯✮✭✼☎✱✾✳ ✬✾❀ ✱✯➉✰✵✰✱❂✼✴✳ ✼ ✪ P ✳✭✳☎✲ ➡ ♦ ➢ ❦✬✫★✭ ➆ ➡ ✮✞✯✱✰ ✪ P ✳✭✳☎✲ ➡ ♦ ➡ ❦✬✫✱✭ ➆✳✲ ➢✱✴✠✵ ✶ ✷✦✸ ✹ ✺ ✺ ✻ ✺ ✼ ✽✄✾☞✿✄❀ ❁ ✸ ❂ ✸ ❃ ❂ ✸ ❄ ❂✄✸ ✸ ✹ ✺ ✺ ✻ ✺ ✼ ❅✱✷ ❃✔❆❈❇ ❂✄❉ ❊ ❂ ✸ ❄ ❂✄✸ ❋✖● ❍✱✸ ✹ ✺ ✺ ✻ ✺ ✼ ❅✠● ❄ ✻ ✼

❁ ✸ ❏✕❑ ❑ ▲◆▼ ❖ P ◗ ❖ ❘ ❑ ❙✕❚ ❚ ❯✱❱ ❲ ❳ ❨ ❲ ❩ ❚ ❬✕❭ ❭ ❪◆❫ ❴ ❵ ❪✕❛ ❜ ❵ ❴ ❝✕❞ ❞ ❡✱❢ ❣ ❤ ❡ ✐ ❥ ❤ ❣

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✒✕✘✛✘✯✖✢✩

➥ ✑ ➎ ✘✌✜✴✔✧❙✛★✌✖✗✥✕✜✴✘ ★✯✚✢✜✁✗▼ ❏✌✚❴✩ ✪ ✫❂✷ ✹ ✱✌✮☎✳ ✹ ✮ ✹ ✳ ✹ ✶✴✳ ✱✛✼ ❼✕➆ ➝ ✫✭✬✯✮✴✮☎✱✯✫☎✳ ✹ ✬✯✮ ➇ ✫✴❀ ✱❂✶✴✳ ✱✛✼✻✼☎✬✯✫✴❁☎✱✛✳☎➈ ✳ ✬❉✼☎✱✯❀✭❄✭✱✯❀ ❧ ✲☎✬✛❀✭✳ ✵✛➢ ✪ ✼☎✱✯❀✭❄✭✱✌❀❨✶❂✫✴✫✭✱✯✲✴✳ ✼ ❼✕➆ ➝ ✫✭✬✯✮✴✮☎✱✯✫☎✳ ✹ ✬✯✮✓✽✛❀ ✬ ✺ ✫❂✷ ✹ ✱✌✮☎✳ ✪ P ✳✭✳☎✲ ✺ ✱❂✼☎✼✰✶ ❆ ✱✛✼ ➇ ✶✛✲✴✲✯✷ ✹ ✫✭✶✴✳ ✹ ✬✯✮✰❍ ✷ ✶✴❊✰✱✌❀✻✲❂❀ ✬❂✳✭✬✛✫✭✬✌✷ ✺ ✱❂✼☎✼☎✶ ❆ ✱❂✼✴➈ ✱✛❋✙✫ P ✶✛✮ ❆ ✱✌❅✤❇❂✱✛✳☎✿✕✱❂✱✌✮❉❇✛❀ ✬❂✿✕✼☎✱✌❀ ➇ P ✳✭✳☎✲❉✫❂✷ ✹ ✱✌✮☎✳✰➈✙✶✛✮✴❅✾♣❚♣❑♣ ✼☎✱✯❀✭❄✭✱✌❀ ➇ P ✳✭✳☎✲❈✼☎✱✯❀✭❄✭✱✌❀✭➈ ✪ ❼✕➆ ➝ ✫☎✬✯✮✴✮✭✱✯✫☎✳ ✹ ✬✯✮●✫❂✷ ✬✴✼☎✱✌❅ ✒✕✘✛✘✯✖❑▼ ★ ➣ ★✯✘✛✔✙✘✛✚❨✦ ✚✗★✯★✙↔ ✪ ✼☎✱✯❀✭❄✭✱✌❀ ✺ ✶ ✹ ✮☎✳ ✶ ✹ ✮✭✼❉✮✭✬ ✹ ✮☎✽✰✬✛❀ ✺ ✶❂✳ ✹ ✬✯✮✻✶✛❇❂✬❂✵✴✳ ✲✰✶✰✼✰✳❈✫❂✷ ✹ ✱✌✮☎✳❈❀ ✱✛➉✴✵☎✱✛✼✰✳ ✼ ➝ ❀ ✬❂✳ ✬✛✫✭✬✌✷ ✼●✳ P ✶✴✳ ✺ ✶ ✹ ✮✰✳ ✶ ✹ ✮ ♠ ✼✰✳✭✶✴✳ ✱✛♥✧✶✛❀ ✱✤✫☎✬ ✺ ✲✯✷ ✱✯❋✞❦ ✪ ✲✰✶✰✼✰✳ P ✹ ✼✰✳ ✬✛❀ ❊ ➇ ✼✰✳ ✶❂✳ ✱✯➈ ✺ ✵☎✼✰✳ ❇❂✱ ✺ ✶ ✹ ✮☎✳ ✶ ✹ ✮✭✱✌❅ ✪ ✹ ✽●✼☎✱✯❀✭❄✭✱✌❀ ➌❂✫❂✷ ✹ ✱✌✮☎✳❈✫✰❀ ✶✰✼ P ✱✛✼ ❧ ✳ P ✱ ✹ ❀✓❄ ✹ ✱✯✿✕✼✻✬✴✽ ♠ ✼✰✳✭✶✴✳ ✱✛♥ ✺ ✶✰❊ ❇❂✱ ✹ ✮✰✫✭✬✯✮✭✼ ✹ ✼✰✳ ✱✙✮☎✳ ❧✴✺ ✵✰✼✰✳●❇✴✱ ❀ ✱✯✫☎✬✯✮✰✫ ✹ ✷ ✱✯❅ ✔✙★✙▼ ➐ ✚

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

➙✙✖✗✖✗✥✙★✯✚❑➙✌★✯✚✢✜✤✚❴❙✛✘✛✚✢✜❂★ ✗♥♠♣♦

www.someSchool.edu/someDepartment/home.index

➡ ✶✆q r✕s s t✢✉☞✈ ✇ ①✁② s✢✇ ②✕✇ s☞✇ ③✄s ①✁④◆⑤✞⑥✔⑦ ✉ ⑧☞②✄②✄①✁✉ s☞✇ ⑧☞②✦s ⑧✢r✕s s t♣④ ①✁⑨ ⑩ ①✔⑨ ❶ t✕⑨ ⑧✁✉ ①✁④ ④ ❷✆③✄s

www.someSchool.edu.

⑦ ⑧✁⑨ s✦❸✕❹ ✇ ④◆❺✁①✕❻ ③✄❼✁✈ s✦❻ ⑧✁⑨✖r✕s s t✢④ ①✁⑨ ⑩ ①✁⑨ q ✲ ♦ r✕s s t❽✉☞✈ ✇ ①✁② s✦④ ①✁②✄❺✁④◆r✕s s t ❾ ❿☞➀☞➁✄❿☞➂✁➃ ➄ ❿☞➂ ➂✄➅ ➆✆❿ ❶ ✉ ⑧☞②✄s ③✕✇ ②✕✇ ② ➇❈➈✱➉✔➊☞❷✱✇ ② s ⑧ ⑤✠⑥✔⑦✢✉ ⑧✕②✄② ①✔✉ s☞✇ ⑧✕②♣④ ⑧✁✉ ➋✄①☞s ➡ ❇✌♦ r✕s s t♣④ ①✁⑨ ⑩ ①✁⑨★③✄s✦r✕⑧☞④ s

www.someSchool.edu

➌ ③✁✇ s☞✇ ② ➇ ❻ ⑧✕⑨✖⑤✠⑥✔⑦✢✉ ⑧✕②✄② ①✔✉ s☞✇ ⑧✕②✦③ s✦t✄⑧✕⑨ s◆❸✁❹✞q ➍ ③✕✉✄✉ ①✕t✄s ④ ➎✱✉ ⑧✕②✄② ①✔✉ s✄✇ ⑧✕②✕➏☞② ⑧✄s☞✇ ❻ ➐✬✇ ② ➇ ✉☞✈ ✇ ①✁② s ➑ ♦ r✕s s t✢④ ①✁⑨ ⑩ ①✁⑨◆⑨ ①✔✉ ①✔✇ ⑩ ①✕④✦⑨ ①☞➒☞❼ ①✁④ s ➓ ①✕④ ④ ③ ➇✕①✔➏☞❻ ⑧✕⑨ ➓ ④ ❾ ❿☞➂ ➔✔→ ➣✄➂ ❿ ➄ ❿☞➂ ➂✄➅ ➆✆❿ ✉ ⑧☞②✄s ③✁✇ ②✕✇ ② ➇↔⑨ ①☞➒☞❼✄①✕④ s ①✁❺ ⑧✕↕✄➙ ①✁✉ s ❶

someDepartment/home.index

❷ ➏ ④ ①✕②✄❺✁④ ➓ ①✕④ ④ ③ ➇✕①↔✇ ② s ⑧✢④ ⑧✕✉✄➋ ①✕s ✘✙▼ ◗r✚

(contains text, references to 10 jpeg images)

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✪➊✮✭✬✯✮✰❍

✲☎✱✌❀ ✼ ✹ ✼✰✳ ✱✙✮☎✳✻✫☎✬✯✮✴✮✭✱✯✫✰✳ ✹ ✬✯✮❂❦ ✬✯✮✭✱❸✬✯❇✔✪ ✱✯✫☎✳ ✹ ✮✻✱❂✶✛✫ P ❼✕➆ ➝ ✫☎✬✯✮✴✮✭✱✯✫✰✳ ✹ ✬✯✮ ❃ ✼☎✬ ✺ ✱r❇✛❀ ✬❂✿✕✼☎✱✌❀ ✼●✫✴❀ ✱✛✶✴✳ ✱ ✺ ✵✯✷ ✳ ✹ ✲✯✷ ✱ ❼✕➆ ➝ ✫☎✬✯✮✴✮✭✱✯✫✰✳ ✹ ✬✯✮✭✼ ➃✛❿ ➛❽➜❂❾ ➂ ✡✴➁✰➀✔✂✁➜☎➃✛❾ ➝✾❍✧✬✯✮✭✱✾✲✰✱✯❀✓✬✯❇✁✪ ✱✌✫☎✳ ✪ ✲✰✱✯❀ ✼ ✹ ✼✴✳ ✱✌✮☎✳❈✫✭✬✯✮✴✮✭✱✯✫✰✳ ✹ ✬✯✮❂❦ ✺ ✵✯✷ ✳ ✹ ✲✯✷ ✱❸✬✯❇✁✪ ✱✯✫✰✳ ✼●✳☎❀ ✶✛✮✭✼☎✽✰✱✯❀☎❀ ✱✯❅✾✿ ✹ ✳ P ✹ ✮ ✬✯✮✭✱ ❼✕➆ ➝ ✫✭✬✯✮❂✮✭✱✯✫☎✳ ✹ ✬✯✮ ✰ q r✕s s t❽✉☞✈ ✇ ①✁② s♣⑨ ①✁✉ ①✬✇ ⑩ ①✕④♣⑨ ①✕④ t✄⑧☞②✄④ ① ➓ ①✕④ ④ ③ ➇✕①➞✉ ⑧☞②✄s ③✁✇ ②✕✇ ② ➇➞r☞s ➓ ✈☞❻☞✇ ✈ ①✔➏ ❺✬✇ ④ t✁✈ ③ ➐✕④◆r✕s ➓ ✈ q♣⑦ ③✕⑨ ④☞✇ ② ➇❽r✕s ➓ ✈ ❻✕✇ ✈ ①✔➏☞❻✕✇ ②☞❺✬✇ ④✄➟ ❹✛⑨ ①✕❻ ①✁⑨ ①✁②☞✉ ①✕❺♣➙ t✄①✄➇ ⑧✕↕✄➙ ①✁✉ s ④ ✴ ♦ ➠✆s ①✕t☞④✢➟ ➡ ➢↔⑨ ①✁t ①✕③✄s ①✕❺➞❻ ⑧✕⑨★①✕③☞✉ r ⑧☞❻❽➟ ❹➞➙ t ①☞➇✢⑧✁↕ ➙ ①✁✉ s ④ ✯ ♦ r✕s s t✢④ ①✁⑨ ⑩ ①✁⑨◆✉☞✈ ⑧☞④ ①✕④◆⑤✠⑥✔⑦ ✉ ⑧☞②✄②✄①✁✉ s☞✇ ⑧☞②☞q ✘✙▼ ◗r✚

SLIDE 3

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✘✛❯❉✥❖✘✴➓✧✖✙✚✕★→✥✙◆➑✒✕✘✛✘✯✖q◗r✚✕★✯★✯✔✌✣✗✚✕★✕✩ ✂✁☎✄✝✆✞✁✝✟✡✠☞☛✝✌✁✝✟☞✍✏✎✝✑✂✟✞✁ ▲ ✒✕✘✛✘✯✖➑✜❂✚☎✒✗➙✌✚✕★✯✘❘◗r✚✕★✯★✯✔✌✣✗✚❨✩ ❃ ❥ ➋ ➆ ➜❂➜ ➇ P ✵ ✺ ✶✛✮✰❍ ❀ ✱❂✶✛❅❂✶✛❇✙✷ ✱❸✽✰✬✛❀ ✺ ✶✴✳☎➈

GET /somedir/page.html HTTP/1.1 Connection: close User-agent: Mozilla/4.0 Accept: text/html, image/gif,image/jpeg Accept-language:fr (extra carriage return, line feed)

❀ ✱✛➉✴✵✰✱❂✼✰✳❉✷ ✹ ✮✭✱ ➇ ✓✕✔ ❼ ❧ ➝✗✖ ➋ ❼ ❧ ✘ ✔ ❥ ✜q✫✭✬ ✺✻✺ ✶✯✮✰❅❂✼✴➈ P ✱❂✶❂❅✛✱✯❀ ✷ ✹ ✮✭✱❂✼ ➆ ✶❂❀☎❀ ✹ ✶ ❆ ✱✤❀ ✱✛✳✭✵❂❀✰✮ ❧ ✷ ✹ ✮✭✱❉✽✴✱❂✱✯❅ ✹ ✮✴❅ ✹ ✫☎✶✴✳ ✱✛✼✻✱✌✮✰❅ ✬✴✽ ✺ ✱✛✼☎✼☎✶ ❆ ✱

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

HTTP/1.1 200 OK

Connection: close Date: Thu, 06 Aug 1998 12:00:15 GMT Server: Apache/1.3.0 (Unix) Last-Modified: Mon, 22 Jun 1998 …... Content-Length: 6821 Content-Type: text/html data data data data data ...

✼✰✳ ✶❂✳✭✵✰✼❸✷ ✹ ✮✭✱ ➇ ✲❂❀ ✬✛✳ ✬✛✫✭✬✌✷ ✼✰✳ ✶❂✳✭✵✰✼●✫✭✬✯❅❂✱ ✼✰✳ ✶❂✳✭✵✰✼●✲ P ❀ ✶✴✼☎✱✯➈ P ✱❂✶❂❅✛✱✯❀ ✷ ✹ ✮✭✱❂✼ ❅❂✶❂✳ ✶ ❧ ✱✌♦ ❆ ♦ ❧ ❀ ✱✛➉✴✵✰✱❂✼✰✳ ✱✯❅ P ✳ ✺ ✷☎✽ ✹ ✷ ✱

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

200 OK

❃ ❀ ✱✛➉✴✵✰✱❂✼✰✳✓✼✰✵✴✫✴✫✭✱✛✱✯❅❂✱✯❅ ❧ ❀ ✱✛➉✴✵✰✱❂✼✰✳✭✱✯❅❸✬✯❇✁✪ ✱✯✫✰✳●✷ ✶✴✳ ✱✯❀ ✹ ✮❈✳ P ✹ ✼ ✺ ✱✛✼☎✼☎✶ ❆ ✱

301 Moved Permanently

❃ ❀ ✱✛➉✴✵✰✱❂✼✰✳ ✱✯❅❸✬✯❇✔✪ ✱✯✫☎✳ ✺ ✬❂❄✭✱✯❅ ❧ ✮✭✱✯✿❑✷ ✬✛✫☎✶✴✳ ✹ ✬✯✮✓✼❂✲☎✱✌✫ ✹ ✽ ✹ ✱✯❅❘✷ ✶❂✳ ✱✯❀ ✹ ✮ ✳ P ✹ ✼ ✺ ✱❂✼☎✼☎✶ ❆ ✱ ➇ ✙ ✬✛✫☎✶✴✳ ✹ ✬✯✮❂❦ ➈

400 Bad Request

❃ ❀ ✱✛➉✴✵✰✱❂✼✰✳ ✺ ✱❂✼☎✼☎✶ ❆ ✱r✮✭✬❂✳✓✵✛✮✰❅❂✱✌❀ ✼✴✳ ✬✴✬✛❅r❇✴❊●✼☎✱✌❀ ❄☎✱✯❀

404 Not Found

❃ ❀ ✱✛➉✴✵✰✱❂✼✰✳ ✱✯❅✤❅❂✬✛✫✰✵ ✺ ✱✌✮☎✳●✮✭✬❂✳❨✽✰✬❂✵✛✮✰❅❸✬✯✮✻✳ P ✹ ✼✻✼☎✱✌❀ ❄✭✱✌❀

505 HTTP Version Not Supported

➏ ❙❘◆✕▼ ✜✴★✯✘q✦ ▼ ❙✛✚➨▼ ❙❘★✯✚✢✜✁✯✚✢✜✂✚☞✛☎❏✧✦ ▼ ✚❴❙✛✘❖✜✴✚✕★✌✖✗✥✧❙✛★✯✚❑◗r✚✕★✯★✯✔✙✣✙✚✢➟ ➍ ◆✙✚✕❯➲★✯✔✗◗❘✖✢✦ ✚❑❏✙✥ ➐ ✚✕★✕✩

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

➟ ➥ ✚❴✦ ❙✛✚✕✘r✘✯✥❘➓✧✥✗➙✗✜✤◆✌✔✠✌✥✗✜✌▼ ✘✛✚✣✢✤✢✤✢ ★✯✚✢✜✁✯✚✢✜✙✩ ✥ t✄①✕②✄④✦⑤✞⑥✔⑦✢✉ ⑧✕②✄② ①✁✉ s☞✇ ⑧☞②✦s ⑧❽t ⑧✁⑨ s✦❸✕❹ ❶ ❺✕①✁❻ ③☞❼✕✈ s✦r☞s s t✢④ ①✔⑨ ⑩ ①✔⑨✖t✄⑧✕⑨ s ❷✆③✄s ➌✠➌✠➌ q ①✕❼✕⑨ ①✁✉ ⑧ ➓ q ❻☞⑨ q ✦ ② ➐☞s r✬✇ ② ➇✢s ➐✕t✄①✕❺♥✇ ②♣④ ①✕② s s ⑧✢t✄⑧✕⑨ s◆❸✁❹❈③✄s ➌✠➌✠➌ q ①✕❼☞⑨ ①✔✉ ⑧ ➓ q ❻✄⑨

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✧ ➟ ➥ ➓✧✖✙✚↕▼ ❙r✔✩★✫✪ ➥ ✒✗✘✛✘✯✖❑✜✴✚☎✒✗➙✙✚✗★✯✘✗✩

GET /~ross/index.html HTTP/1.0

✬ ➐✢s ➐✕t✁✇ ② ➇✢s r✬✇ ④♣✇ ② ❶ r✬✇ s♣✉ ③✕⑨ ⑨✄✇ ③ ➇✕① ⑨ ①✕s ❼☞⑨ ②✦s ➌ ✇ ✉ ①✁❷ ➏ ➐☞⑧☞❼♣④ ①✕②✄❺ s r✬✇ ④ ➓ ✇ ②✕✇ ➓ ③✁✈ ❶ ↕✁❼ s✦✉ ⑧ ➓ t✁✈ ①✕s ①✁❷ ✭✝✮ ⑤ ⑨ ①✕➒☞❼ ①✕④ s◆s ⑧❽r☞s s t✢④ ①✔⑨ ⑩ ①✁⑨ ✯ ➟ ♦ ✥✙✥✕❱→✔✙✘→✜❂✚✕★✌✖✗✥✕❙✯★✯✚❑◗r✚✕★✯★✯✔✌✣✗✚➑★✯✚❴❙✛✘ ➒ ➓↕✒✕✘✛✘✯✖❖★✯✚✢✜✔✛✚✢✜✌✰

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✵✰✳ P ✱✌✮✰✳ ✹ ✫☎✶✴✳ ✹ ✬✯✮ ❆ ✬❂✶✯✷ ❦ ✫✭✬✯✮☎✳✰❀ ✬✌✷ ✶❂✫✴✫✭✱✛✼☎✼❈✳ ✬❉✼☎✱✯❀✭❄✭✱✌❀✻❅❂✬✛✫☎✵ ✺ ✱✌✮☎✳✭✼ ✪ ✼✰✳ ✶❂✳ ✱✙✷ ✱✛✼☎✼✛❦ ✫❂✷ ✹ ✱✌✮☎✳ ✺ ✵☎✼✴✳✻✲❂❀ ✱❂✼☎✱✌✮☎✳ ✶✴✵✴✳ P ✬✛❀ ✹ ✱ ✶✴✳ ✹ ✬✯✮ ✹ ✮✓✱✛✶❂✫ P ❀ ✱✯➉✰✵✰✱✛✼✰✳ ✪ ✶✴✵✴✳ P ✬✛❀ ✹ ✱ ✶✴✳ ✹ ✬✯✮❂❦❂✳ ❊✛✲ ✹ ✫✭✶✌✷ ✷ ❊✾✮✭✶ ✺ ✱ ❧ ✲✰✶✰✼☎✼✰✿✕✬✛❀☎❅ ✲

authorization:

P ✱❂✶❂❅✛✱✯❀ ✷ ✹ ✮✭✱ ✹ ✮❈❀ ✱✯➉✰✵✰✱❂✼✰✳ ❃ ✹ ✽✾✮✭✬❉✶✴✵✴✳ P ✬✛❀ ✹ ✱ ✶❂✳ ✹ ✬✌✮ ✲❂❀ ✱✛✼☎✱✌✮☎✳ ✱✌❅ ❧ ✼☎✱✯❀✭❄✭✱✯❀❈❀ ✱✛✽✴✵☎✼✰✱❂✼ ✶❂✫✴✫✭✱✛✼☎✼ ❧ ✼☎✱✙✮✰❅❂✼

WWW authenticate:

P ✱❂✶❂❅✛✱✯❀●✷ ✹ ✮✭✱ ✹ ✮●❀ ✱✛✼✴✲✰✬✯✮✭✼☎✱ ❏✧✦ ▼ ✚❴❙✯✘ ★✯✚✢✜✁✯✚✢✜ ❼✄④ ❼ ③✁✈✄r✕s s t✢⑨ ①✕➒☞❼ ①✁④ s ➓ ④ ➇ ✳ ❹✱➟ ✴✄③☞❼ s r✕⑧✕⑨✄✇ ✵ ③✄s☞✇ ⑧☞②✢⑨ ①✕➒✕q

WWW authenticate:

❼✄④ ❼ ③✁✈✄r✕s s t✢⑨ ①✕➒☞❼ ①✁④ s ➓ ④ ➇ ✶

Authorization:line

❼✄④ ❼ ③✁✈✄r✕s s t✢⑨ ①✁④ t✄⑧✕②✄④ ① ➓ ④ ➇ ❼✄④ ❼ ③✁✈✄r✕s s t✢⑨ ①✕➒☞❼ ①✁④ s ➓ ④ ➇ ✶

Authorization:line

❼✄④ ❼ ③✁✈✄r✕s s t✢⑨ ①✁④ t✄⑧✕②✄④ ① ➓ ④ ➇ ✳ ✹ ✺ ✱

SLIDE 4

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✼☎✱✯❀✭❄✭✱✌❀❨✼☎✱✌✮✰❅✛✼ ♠ ✫✭✬✴✬✯❁ ✹ ✱✛♥✢✳ ✬ ✫❂✷ ✹ ✱✌✮☎✳ ✹ ✮❈❀ ✱❂✼✴✲✰✬✯✮✭✼☎✱

Set-cookie: #

✪ ✫❂✷ ✹ ✱✌✮☎✳❈✲❂❀ ✱✛✼☎✱✌✮☎✳❈✫✭✬✴✬✯❁ ✹ ✱ ✹ ✮ ✷ ✶❂✳ ✱✯❀✻❀ ✱✛➉✴✵✰✱❂✼✰✳ ✼

cookie: #

✪ ✼☎✱✯❀✭❄✭✱✌❀ ✺ ✶✴✳☎✫ P ✱✛✼ ✲❂❀ ✱✛✼☎✱✌✮☎✳ ✱✌❅✯❍ ✫✭✬✴✬✯❁ ✹ ✱✾✿ ✹ ✳ P ✼☎✱✯❀✭❄✭✱✌❀✭❍ ✼✰✳ ✬✛❀ ✱✯❅✤✫☎✬✴✬✯❁ ✹ ✱❂✼ ❃ ✶✴✵✴✳ P ✱✌✮☎✳ ✹ ✫✭✶❂✳ ✹ ✬✯✮ ❃ ❀ ✱ ✺ ✱ ✺ ❇❂✱✯❀ ✹ ✮ ❆ ✵✰✼☎✱✌❀ ✲❂❀ ✱✛✽✰✱✯❀ ✱✌✮✰✫☎✱❂✼ ❧ ✲❂❀ ✱✯❄ ✹ ✬❂✵✰✼ ✫ P ✬ ✹ ✫✭✱❂✼ ❏✧✦ ▼ ✚❴❙✯✘ ★✯✚✢✜✁✯✚✢✜ ❼✄④ ❼ ③✁✈✄r✕s s t✢⑨ ①✕➒☞❼ ①✁④ s ➓ ④ ➇ ❼✄④ ❼ ③✁✈✄r✕s s t✢⑨ ①✁④ t✄⑧✕②✄④ ① ✶

Set-cookie: #

❼✄④ ❼ ③✁✈✄r✕s s t✢⑨ ①✕➒☞❼ ①✁④ s ➓ ④ ➇

cookie: #

❼✄④ ❼ ③✁✈✄r✕s s t✢⑨ ①✁④ t✄⑧✕②✄④ ① ➓ ④ ➇ ❼✄④ ❼ ③✁✈✄r✕s s t✢⑨ ①✕➒☞❼ ①✁④ s ➓ ④ ➇

cookie: #

❼✄④ ❼ ③✁✈✄r✕s s t✢⑨ ①✁④ t✄⑧✕②✄④ ① ➓ ④ ➇ ✫✭✬✴✬✯❁ ✹ ✱✯❍ ✼✴✲✰✱✯✫✰✳ ✹ ✽ ✹ ✫ ✶❂✫✰✳ ✹ ✬✯✮ ✫✭✬✴✬✯❁ ✹ ✱✯❍ ✼✴✲✰✱✯✫✰✳ ✹ ✽ ✹ ✫ ✶❂✫✰✳ ✹ ✬✯✮

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✓ ✬✴✶✌✷ ❦ ❅❂✬✯✮☞✑ ✳✓✼☎✱✌✮✰❅❸✬✯❇✔✪ ✱✯✫☎✳ ✹ ✽ ✫❂✷ ✹ ✱✌✮☎✳ P ✶✰✼●✵✴✲❂❍ ✳ ✬✛❍ ❅✛✶✴✳ ✱❸✼✰✳ ✬✛❀ ✱✯❅ ➇ ✫✭✶✛✫ P ✱✯❅✯➈✕❄✭✱✯❀ ✼ ✹ ✬✯✮ ✪ ✫❂✷ ✹ ✱✌✮☎✳❂❦✰✼❂✲☎✱✌✫ ✹ ✽✴❊❸❅❂✶✴✳✭✱❉✬✴✽ ✫✭✶✛✫ P ✱✯❅✤✫✭✬✛✲✰❊ ✹ ✮ P ✳✭✳☎✲❉❀ ✱✛➉✴✵✰✱❂✼✰✳

If-modified-since: <date>

✪ ✼☎✱✯❀✭❄✭✱✌❀✰❦✛❀ ✱❂✼❂✲☎✬✯✮✭✼☎✱✤✫☎✬✯✮☎✳ ✶ ✹ ✮✭✼ ✮✭✬❉✬✯❇✁✪ ✱✯✫✰✳ ✹ ✽❉✫☎✶❂✫ P ✱✌❅✾✫☎✬✛✲☎❊❸✵✴✲❂❍ ✳ ✬✛❍ ❅❂✶✴✳✭✱✙❦

HTTP/1.0 304 Not Modified

❏✧✦ ▼ ✚❴❙✯✘ ★✯✚✢✜✁✯✚✢✜ r✕s s t✢⑨ ①✕➒☞❼ ①✁④ s ➓ ④ ➇

If-modified-since: <date>

r✕s s t✢⑨ ①✁④ t✄⑧✕②✄④ ①

HTTP/1.0 304 Not Modified

✬✯❇✔✪ ✱✯✫☎✳ ✮✭✬❂✳ ✺ ✬✛❅ ✹ ✽ ✹ ✱✌❅ r✕s s t✢⑨ ①✕➒☞❼ ①✁④ s ➓ ④ ➇

If-modified-since: <date>

r✕s s t✢⑨ ①✁④ t✄⑧✕②✄④ ①

HTTP/1.1 200 OK …

<data>

✬✯❇✔✪ ✱✯✫☎✳ ✺ ✬✛❅ ✹ ✽ ✹ ✱✌❅

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✵✰✼☎✱✯❀❨✼✰✱✛✳ ✼❸❇✛❀ ✬❂✿✕✼☎✱✌❀✰❦ ♣❑♣❚♣ ✶❂✫✴✫✭✱❂✼☎✼✰✱❂✼❈❄ ✹ ✶ ✿✕✱✌❇✾✫☎✶❂✫ P ✱ ✪ ✫❂✷ ✹ ✱✌✮☎✳✓✼☎✱✌✮✴❅❂✼✻✶✌✷ ✷ P ✳✭✳☎✲ ❀ ✱✛➉✴✵✰✱❂✼✰✳ ✼●✳ ✬ ✿✕✱✌❇✾✫☎✶❂✫ P ✱ ✲ ✇ ❻◆⑧✁↕ ➙ ①✁✉ s◆③✄s ➌ ①✔↕ ✉ ③✕✉ r✕①✬➏ ➌ ①✔↕➞✉ ③✕✉ r✕① ✇ ➓◆➓ ①✕❺✆✇ ③ s ①✬✈ ➐➞⑨ ①☞s ❼☞⑨ ②✄④ ⑧✕↕✄➙ ①✁✉ s♣✇ ②♣r✕s s t ⑨ ①✁④ t✄⑧☞②☞④ ① ✲ ①✔✈ ④ ①➞⑨ ①☞➒✕❼ ①✕④ s ④✖⑧✕↕✄➙ ①✔✉ s ❻☞⑨ ⑧ ➓ ⑧✁⑨ ✇ ➇✔✇ ②♣④ ①✁⑨ ⑩ ①✁⑨ ➏ s r✕①✕②✢⑨ ①✕s ❼☞⑨ ②✄④◆r✕s s t ⑨ ①✁④ t✄⑧☞②☞④ ①✢s ⑧➞✉✄✈ ✇ ①✕② s ★❉✥✙✔✧✦ ✩ ✼☎✶❂✳ ✹ ✼☎✽✰❊✾✫❂✷ ✹ ✱✌✮☎✳❈❀ ✱✯➉✰✵✰✱✛✼✰✳✓✿ ✹ ✳ P ✬❂✵✰✳ ✹ ✮☎❄☎✬✌✷ ❄ ✹ ✮ ❆ ✬✛❀ ✹ ❆✯✹ ✮✻✼☎✱✯❀✭❄✭✱✌❀ ❍ ❀ ✻ ❂✄✺ ■ ➝ ❀ ✬❂❋✛❊ ✼☎✱✯❀✭❄✭✱✌❀ ❍ ❀ ✻ ❂✄✺ ■ ❏✕❑ ❑ ▲◆▼ ❖ P ◗ ❖ ❘ ❑ ❙✕❚ ❚ ❯✱❱ ❲ ❳ ❨ ❲ ❩ ❚ ❬✕❭ ❭ ❪◆❫ ❴ ❵ ❪✕❛ ❜ ❵ ❴ ❝✕❞ ❞ ❡✱❢ ❣ ❤ ❡ ✐ ❥ ❤ ❣ ❙✕❚ ❚ ❯✱❱ ❲ ❳ ❨ ❲ ❩ ❚ ❝✕❞ ❞ ❡✱❢ ❣ ❤ ❡ ✐ ❥ ❤ ❣ ❏✕❑ ❑ ▲◆▼ ❖ P ◗ ❖ ❘ ❑ ❬✕❭ ❭ ❪◆❫ ❴ ❵ ❪✕❛ ❜ ❵ ❴ ❁ ✸ ✻ ✼✄✻ ✺ ❊ ❂ ✸ ❄ ❂✄✸ ❁ ✸ ✻ ✼✄✻ ✺ ❊ ❂ ✸ ❄ ❂✄✸

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

★✯★✌➙✙◗r✚❨✩ ❏✯✔✗❏✗✒✕✚↕▼ ★ ➣ ❏✧✦ ✥✌★✯✚✢↔ ✘✯✥q❏✧✦ ▼ ✚❴❙✛✘✁ ✚✢➟ ✣✕➟ ☛✕▼ ❙❘★✛✔✗◗r✚ ❙✯✚✗✘✛❯❉✥✕✜✯❱✄✂ ▲ ★✌◗r✔✧✦ ✦ ✚✧✜❘✜❂✚✕★✌✖✗✥✕❙✯★✯✚➑✘✙▼ ◗r✚❨✩ ❏✌✔✙❏✗✒✕✚ ➣ ❏✧✦ ✥✌★✯✚✢✜✛↔❈✘✯✥ ❏✧✦ ▼ ✚❴❙✯✘ ▲ ➐ ✚✧❏✗✜❂✚✗✔✙★✯✚➑✘✌✜❂✔✌◆✙◆✕▼ ❏→✘✯✥ ➐ ▼ ★✯✘✛✔✕❙✯✘r★✯✚✢✜✁✯✚✢✜❂★ ❃ ✷ ✹ ✮✴❁✻✬❂✵✴✳❨✬✴✽ ✹ ✮☎✼✰✳ ✹ ✳✭✵✴✳ ✹ ✬✯✮✭✶✯✷ ➌✯✷ ✬✛✫✭✶✌✷ ➜ ➋ ➝ ✮✭✱✛✳☎✿✕✬✛❀☎❁❈✬✴✽✴✳ ✱✌✮ ❇❂✬❂✳✭✳✴✷ ✱✌✮✭✱✌✫✴❁ ✬✛❀ ✹ ❆✌✹ ✮ ✼☎✱✯❀✭❄✭✱✌❀ ✼ ✿ ✹ ❉✕❀ ✻ ❍ ☎☞✺ ■ ❂ ✸ ✺ ❂ ■ ✻ ✺ ❊ ■ ✻ ■ ✹ ■ ✻ ❁ ✺

✄❀

✺ ❂ ■ ✆✬❁ ✸ ✝ ✞ ✟ ❋✦❉✄✿ ❊✡✠ ❆ ❅ ✞ ☛ ☞ ❋♣❉ ✿ ❊

❍ ❂ ❊ ❊ ❀ ✻ ✺ ✝ ✇ ②✄④ s✄✇ s ❼ s☞✇ ⑧✕② ③✁✈ ✉ ③✕✉ r✕①

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✳☎❀ ✶✛✮✭✼☎✽✴✱✯❀❨✽ ✹ ✷ ✱✾✳ ✬❂➌☎✽❂❀ ✬ ✺ ❀ ✱ ✺ ✬❂✳ ✱ P ✬✴✼✰✳ ✪ ✫❂✷ ✹ ✱✌✮☎✳☎➌☎✼☎✱✯❀✭❄✭✱✌❀ ✺ ✬✛❅❂✱✙✷ ❃ ❽✰❾ ❿ ➀✛➁✗➂ ✟ ✼ ✹ ❅❂✱✾✳ P ✶✴✳ ✹ ✮ ✹ ✳ ✹ ✶✴✳ ✱❂✼●✳☎❀ ✶✛✮✭✼☎✽✴✱✯❀ ➇ ✱ ✹ ✳ P ✱✯❀✓✳ ✬❂➌✰✽❂❀ ✬ ✺ ❀ ✱ ✺ ✬❂✳ ✱✌➈ ❃ ➃✴➀❂➄✙➅ ➀✛➄✔✟ ❀ ✱ ✺ ✬❂✳✭✱ P ✬✴✼✰✳ ✪ ✽✴✳☎✲✯❦✬✫✱✭ ➆ ✮✠✰✞✮ ✪ ✽✴✳☎✲❈✼☎✱✌❀✭❄✭✱✯❀✴❦✛✲☎✬✛❀✭✳ ✲ ➡ ✌ ✻ ❀ ❂✖■ ✸

❊ ✌ ❂ ✸ ✍✏✎ ✶ ❊ ❂ ✸ ❄ ❂✄✸ ✍✏✎ ✶ ✹ ❊ ❂ ✸ ✻ ✺ ■ ❂✄✸ ✌

❂ ✍✏✎ ✶ ❍ ❀ ✻ ❂✄✺ ■ ❀ ❁ ❍

✄❀

✌ ✻ ❀ ❂ ❊ ✑ ❊ ■ ❂✓✒ ✸ ❂✓✒✞❁ ■ ❂ ✌ ✻ ❀ ❂ ❊ ✑ ❊ ■ ❂✓✒ ✹ ❊ ❂ ✸

■✕✔

❁ ❊ ■

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✽✴✳☎✲❉✫✛✷ ✹ ✱✙✮☎✳✻✫☎✬✯✮☎✳ ✶❂✫✰✳ ✼❈✽✴✳☎✲❈✼☎✱✯❀✭❄✭✱✌❀ ✶✴✳❈✲✰✬✛❀✭✳ ✲ ➡ ❧ ✼❂✲☎✱✌✫ ✹ ✽✴❊ ✹ ✮ ❆ ❼✕➆ ➝ ✶✰✼ ✳☎❀ ✶✛✮✭✼✴✲✰✬✛❀✭✳❈✲✴❀ ✬❂✳ ✬✛✫☎✬✌✷ ✪ ✳✭✿✕✬✾✲☎✶✛❀ ✶✯✷ ✷ ✱✗✷ ❼✕➆ ➝ ✫☎✬✯✮✴✮✭✱✯✫✰✳ ✹ ✬✯✮✭✼ ✬✛✲✰✱✌✮✭✱✯❅✗❦ ❃ ✫✭✬✯✮☎✳✰❀ ✬✌✷ ❦ ✱✛❋✌✫ P ✶✯✮ ❆ ✱ ✫✭✬ ✺✻✺ ✶✯✮✰❅❂✼ ❧ ❀ ✱❂✼✴✲✰✬✯✮✭✼☎✱❂✼ ❇❂✱✛✳✭✿✕✱❂✱✙✮❈✫✛✷ ✹ ✱✙✮☎✳ ❧ ✼✰✱✯❀✭❄✭✱✯❀✰♦ ♠ ✬❂✵✴✳✓✬✴✽❸❇❂✶✛✮✰❅✤✫✭✬✯✮☎✳✰❀ ✬✌✷ ♥ ❃ ❅❂✶❂✳ ✶✯❦ ✽ ✹ ✷ ✱✤❅❂✶✴✳ ✶❉✳ ✬❂➌✰✽❂❀ ✬ ✺ ✼☎✱✯❀✭❄✭✱✌❀ ✪ ✽✴✳☎✲❈✼☎✱✌❀✭❄✭✱✯❀ ✺ ✶ ✹ ✮☎✳ ✶ ✹ ✮✭✼ ♠ ✼✰✳ ✶❂✳ ✱✛♥ ❦ ✫☎✵❂❀☎❀ ✱✌✮☎✳❈❅ ✹ ❀ ✱✌✫☎✳ ✬✛❀ ❊ ❧ ✱✛✶❂❀✴✷ ✹ ✱✌❀ ✶✴✵✴✳ P ✱✌✮☎✳ ✹ ✫✭✶❂✳ ✹ ✬✯✮ ✭ ❼ ➝ ✫❂✷ ✹ ✱✌✮☎✳ ✭ ❼ ➝ ✼☎✱✯❀✭❄✭✱✌❀ ✎ ✷☞✶★❍ ❁ ✺ ■ ✸ ❁✄❀ ❍ ❁ ✺ ✺ ❂✄❍ ■ ✻ ❁ ✺ ✿ ❁ ✸ ■✗✖ ✞ ✎ ✷☞✶✗✘

■
✖❍

❁ ✺ ✺ ❂ ❍ ■ ✻ ❁ ✺ ✿ ❁ ✸ ■✗✖ ✟

SLIDE 5

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✔✙◗❘✖✢✦ ✚❑❏✙✥✙◗❘◗r✔✧❙ ➐ ★✕✩ ✪ ✼☎✱✌✮☎✳✓✶✰✼ ❥ ➋ ➆ ➜❂➜ ✳ ✱✛❋✌✳❨✬❂❄✭✱✌❀ ✫✭✬✯✮☎✳✰❀ ✬✌✷❂✫ P ✶✛✮❂✮✭✱✙✷ ✪

USER username

✪

PASS password

✪

LIST

❀ ✱✛✳✭✵❂❀✰✮❉✷ ✹ ✼✰✳✓✬✴✽❈✽ ✹ ✷ ✱ ✹ ✮ ✫☎✵❂❀☎❀ ✱✌✮☎✳❈❅ ✹ ❀ ✱✌✫☎✳ ✬✛❀ ❊ ✪

RETR filename

❀ ✱✛✳☎❀ ✹ ✱✛❄✭✱❂✼ ➇ ❆ ✱✯✳ ✼✴➈✙✽ ✹ ✷ ✱ ✪

STOR filename

✼✰✳ ✬✛❀ ✱✛✼ ➇ ✲✴✵✰✳✭✼✴➈✙✽ ✹ ✷ ✱❸✬✯✮☎✳ ✬❸❀ ✱ ✺ ✬❂✳✭✱ P ✬✴✼✰✳ ❧ ✔✙◗❘✖✢✦ ✚❚✜✴✚✕✘✯➙✗✜✌❙→❏✙✥ ➐ ✚✗★ ✪ ✼✰✳ ✶❂✳✭✵✰✼●✫✭✬✯❅❂✱❸✶✛✮✰❅✤✲ P ❀ ✶✰✼☎✱ ➇ ✶✴✼ ✹ ✮ P ✳✭✳☎✲❂➈ ✪

331 Username OK, password required

✪

125 data connection already open; transfer starting

✪

425 Can’t open data connection

✪

452 Error writing file

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✒✢✜❂✚✗✚❑◗r✔✁❂✥✗✜r❏✙✥✗◗❘✖✗✥✕❙✯✚❴❙✛✘✛★✕✩ ✪ ✵✰✼☎✱✯❀❨✶ ❆ ✱✌✮✰✳ ✼ ✪ ✺ ✶ ✹ ✷☎✼✰✱✯❀✭❄✭✱✯❀ ✼ ✪ ✼ ✹ ✺ ✲✛✷ ✱ ✺ ✶ ✹ ✷✴✳☎❀ ✶✛✮✭✼☎✽✰✱✯❀ ✲❂❀ ✬✛✳ ✬✛✫✭✬✌✷ ❦✴✼ ✺ ✳☎✲ ✚✧✼☎✱✯❀ ❥ ❆ ✱✌✮☎✳ ✪ ✶✛♦ ❁❂♦ ✶✛♦ ♠ ✺ ✶ ✹ ✷✴❀ ✱❂✶✛❅❂✱✯❀✭♥ ✪ ✫✭✬ ✺ ✲✰✬✴✼ ✹ ✮ ❆✯❧ ✱✯❅ ✹ ✳ ✹ ✮ ❆✌❧ ❀ ✱✛✶❂❅ ✹ ✮ ❆ ✺ ✶ ✹ ✷ ✺ ✱✛✼☎✼☎✶ ❆ ✱❂✼ ✪ ✱✌♦ ❆ ♦ ❧ ✔ ✵❂❅❂✬✛❀ ✶ ❧ ✲ ✹ ✮✭✱ ❧ ✱✗✷ ✺●❧ ✂ ✱✯✳ ✼✴✫✭✶✛✲☎✱☎✄❉✱✛✼☎✼☎✱✌✮ ❆ ✱✯❀ ✪ ✬❂✵✴✳ ❆ ✬ ✹ ✮ ❆✯❧✯✹ ✮✰✫☎✬ ✺●✹ ✮ ❆❸✺ ✱❂✼☎✼✰✶ ❆ ✱✛✼ ✼✰✳ ✬✛❀ ✱✯❅❸✬✯✮✻✼☎✱✯❀✭❄✭✱✯❀ ✹ ❊ ❂ ✸✡✒✆● ✻ ❀ ❉✄❁ ✾ ❁ ✹ ■ ✼ ❁ ✻ ✺ ✼ ✒✆❂ ❊ ❊

❂✝✆ ✹ ❂✄✹ ❂ ✒✆● ✻ ❀ ❊ ❂ ✸ ❄ ❂✄✸ ✹ ❊ ❂ ✸

❂✄✺ ■ ✹ ❊ ❂ ✸

❂✄✺ ■ ✒✆● ✻ ❀ ❊ ❂ ✸ ❄ ❂✄✸ ✹ ❊ ❂ ✸

❂✄✺ ■ ✹ ❊ ❂ ✸

❂✄✺ ■ ✒✆● ✻ ❀ ❊ ❂ ✸ ❄ ❂✄✸ ✹ ❊ ❂ ✸

❂✄✺ ■ ❧ ■ ➥ ➎ ❧ ■ ➥ ➎ ❧ ■ ➥ ➎

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✔✕▼ ✦ ❧ ✚✢✜✁✯✚✢✜❂★ ✪ ✺ ✶ ✹ ✷ ❇❂✬❂❋ ✫☎✬✯✮☎✳ ✶ ✹ ✮✭✼ ✹ ✮✰✫✭✬ ✺●✹ ✮ ❆ ✺ ✱❂✼☎✼☎✶ ❆ ✱✛✼ ➇ ❊✴✱✛✳✓✬❂✳❈❇❂✱✤❀ ✱❂✶❂❅✌➈ ✽✰✬✛❀✓✵✰✼☎✱✌❀ ✪ ✺ ✱❂✼☎✼☎✶ ❆ ✱ ➉✴✵☎✱✯✵✰✱❉✬✴✽●✬❂✵✴✳ ❆ ✬ ✹ ✮ ❆ ➇ ✳ ✬✤❇✴✱❸✼☎✱✌✮☎✳✰➈ ✺ ✶ ✹ ✷ ✺ ✱✛✼☎✼☎✶ ❆ ✱❂✼ ✪ ✼ ✺ ✳☎✲❉✲❂❀ ✬❂✳ ✬✛✫✭✬✌✷ ❇❂✱✛✳✭✿✕✱✛✱✌✮ ✺ ✶ ✹ ✷ ✼☎✱✯❀✭❄✭✱✌❀✓✳ ✬❉✼☎✱✌✮✰❅❸✱ ✺ ✶ ✹ ✷ ✺ ✱❂✼☎✼☎✶ ❆ ✱✛✼ ❃ ✫❂✷ ✹ ✱✌✮☎✳❂❦✰✼✰✱✌✮✰❅ ✹ ✮ ❆❸✺ ✶ ✹ ✷ ✼☎✱✯❀✭❄✭✱✌❀ ❃ ♠ ✼☎✱✌❀✭❄✭✱✯❀✭♥ ❦✛❀ ✱✯✫✭✱ ✹ ❄ ✹ ✮ ❆❸✺ ✶ ✹ ✷ ✼☎✱✯❀✭❄✭✱✌❀ ✒✆● ✻ ❀ ❊ ❂ ✸ ❄ ❂✄✸ ✹ ❊ ❂ ✸

❂✄✺ ■ ✹ ❊ ❂ ✸

❂✄✺ ■ ✒✆● ✻ ❀ ❊ ❂ ✸ ❄ ❂✄✸ ✹ ❊ ❂ ✸

❂✄✺ ■ ✹ ❊ ❂ ✸

❂✄✺ ■ ✒✆● ✻ ❀ ❊ ❂ ✸ ❄ ❂✄✸ ✹ ❊ ❂ ✸

❂✄✺ ■ ❧ ■ ➥ ➎ ❧ ■ ➥ ➎ ❧ ■ ➥ ➎

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✵✰✼☎✱❂✼●✳☎✫✰✲●✳✭✬❸❀ ✱✙✷ ✹ ✶✛❇✙✷ ❊❉✳☎❀ ✶✛✮☎✼☎✽✰✱✯❀❨✱ ✺ ✶ ✹ ✷ ✺ ✼ ❆ ✽❂❀ ✬ ✺ ✫✛✷ ✹ ✱✙✮☎✳✓✳ ✬ ✼☎✱✯❀✭❄✭✱✌❀ ❧ ✲✰✬✛❀✭✳ ✲ ✰ ✪ ❅ ✹ ❀ ✱✯✫☎✳✻✳☎❀ ✶✛✮✭✼☎✽✰✱✌❀✴❦✰✼✰✱✌✮✰❅ ✹ ✮ ❆ ✼☎✱✯❀✭❄✭✱✯❀✓✳✭✬❸❀ ✱✯✫☎✱ ✹ ❄ ✹ ✮ ❆ ✼☎✱✯❀✭❄✭✱✌❀ ✪ ✳ P ❀ ✱❂✱✤✲ P ✶✰✼☎✱✛✼✻✬✴✽❉✳☎❀ ✶✛✮✭✼☎✽✴✱✯❀ ❃ P ✶✛✮✰❅❂✼ P ✶✛❁ ✹ ✮ ❆ ➇ ❆ ❀ ✱❂✱✛✳ ✹ ✮ ❆ ➈ ❃ ✳☎❀ ✶✛✮✭✼☎✽✴✱✯❀ ❃ ✫❂✷ ✬✴✼✰✵✴❀ ✱ ✪ ✫✭✬ ✺✻✺ ✶✯✮✰❅✛➌✴❀ ✱✛✼✴✲☎✬✯✮✭✼☎✱ ✹ ✮☎✳ ✱✯❀ ✶❂✫✰✳ ✹ ✬✯✮ ❃ ✫✭✬ ✺✻✺ ✶✯✮✰❅❂✼✛❦ ❥ ➋ ➆ ➜ ✳ ✱✛❋✌✳ ❃ ❀ ✱❂✼✴✲✰✬✯✮✭✼☎✱✙❦ ✼✰✳✭✶✴✳✭✵✰✼●✫☎✬✛❅❂✱❸✶✛✮✰❅✤✲ P ❀ ✶✴✼☎✱

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

S: 220 hamburger.edu

C: HELO crepes.fr S: 250 Hello crepes.fr, pleased to meet you C: MAIL FROM: <alice@crepes.fr> S: 250 alice@crepes.fr... Sender ok C: RCPT TO: <bob@hamburger.edu> S: 250 bob@hamburger.edu ... Recipient ok C: DATA S: 354 Enter mail, end with "." on a line by itself C: Do you like ketchup? C: How about pickles? C: . S: 250 Message accepted for delivery C: QUIT S: 221 hamburger.edu closing connection

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✘✌✜✰➓➑★✌◗r✘✯✖❚▼

❙✛✘✛✚✢✜❂✔✙❏✌✘✙▼ ✥✕❙❘◆✗✥✗✜ ➓✧✥✗➙✗✜❂★✛✚❨✦ ◆✢✩ ✪

telnet servername 25

✪ ✼☎✱❂✱ ✲✠✲ ➢ ❀ ✱✯✲✯✷ ❊●✽✛❀ ✬ ✺ ✼☎✱✯❀✭❄✭✱✯❀ ✪ ✱✌✮☎✳✭✱✯❀ ✘ ✔✞✙ ✖ ❧ ✄ ❥ ➜ ✙ ✭✆✫ ✖ ✄ ❧ ✫ ➆ ➝ ❼q❼ ✖ ❧ ✜ ❥ ❼ ❥ ❧ ✘ ✚ ➜ ❼ ✫✭✬ ✺✻✺ ✶✯✮✰❅❂✼ ✶✛❇❂✬❂❄✭✱❘✷ ✱✛✳✭✼✻❊✴✬❂✵❈✼☎✱✙✮✰❅❉✱ ✺ ✶ ✹ ✷ ✿ ✹ ✳ P ✬❂✵✴✳✻✵☎✼ ✹ ✮ ❆ ✱ ✺ ✶ ✹ ✷❂✫❂✷ ✹ ✱✌✮☎✳ ➇ ❀ ✱❂✶✛❅❂✱✯❀☎➈ ✑❨✥✗◗❘✖✙✔✕✜✯▼ ★✯✥✧❙❘❯✾▼ ✘✌✒❚✒✕✘✛✘✯✖ ✪ P ✳✭✳☎✲✯❦✛✲✰✵✯✷ ✷ ✪ ✱ ✺ ✶ ✹ ✷ ❦✛✲✴✵✰✼ P ✪ ❇❂✬❂✳ P✾P ✶❂❄✭✱ ❥ ➋ ➆ ➜❂➜ ✫✭✬ ✺✻✺ ✶✯✮✰❅✛➌✴❀ ✱✛✼✴✲☎✬✯✮✭✼☎✱ ✹ ✮✰✳ ✱✯❀ ✶❂✫✰✳ ✹ ✬✯✮ ❧ ✼✰✳ ✶❂✳✭✵☎✼❉✫✭✬✛❅✛✱❂✼ ✪ P ✳✭✳☎✲✯❦ ✺ ✵✯✷ ✳ ✹ ✲✯✷ ✱❸✬✯❇✁✪ ✱✯✫✰✳ ✼ ✹ ✮ ✽ ✹ ✷ ✱❸✼☎✱✌✮☎✳ ✹ ✮✻✼☎✱✯✲✰✶❂❀ ✶✴✳ ✱ ✫✭✬✯✮✴✮☎✱✯✫☎✳ ✹ ✬✯✮✭✼ ✪ ✼ ✺ ✳☎✲✯❦ ✺ ✵✛✷ ✳ ✹ ✲✯✷ ✱ ✺ ✱❂✼☎✼☎✶ ❆ ✱ ✲✰✶❂❀✭✳ ✼❈✼☎✱✌✮☎✳ ✹ ✮✻✬✯✮✭✱ ✫✭✬✯✮✴✮☎✱✯✫☎✳ ✹ ✬✯✮

SLIDE 6

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✺ ✳☎✲✯❦✛✲✴❀ ✬❂✳ ✬✛✫☎✬✌✷✰✽✰✬✛❀❨✱✛❋✌✫ P ✶✛✮ ❆✯✹ ✮ ❆ ✱ ✺ ✶ ✹ ✷ ✺ ✼ ❆ ✼ ✫★✭ ➆ ✵ ✲✞✲ ❦✴✼✰✳ ✶✛✮✰❅✛✶❂❀☎❅❸✽✰✬✛❀✓✳ ✱✛❋✌✳ ✺ ✱❂✼☎✼☎✶ ❆ ✱❸✽✰✬✛❀ ✺ ✶✴✳✴❦ ✪ P ✱❂✶❂❅✛✱✯❀●✷ ✹ ✮✭✱❂✼ ❧ ✱✌♦ ❆ ♦ ❧ ✲ ⑤✞⑧✗✴ ✲

⑧ ➓ ✴ ✲ ➠✞❼☞↕✄➙ ①✔✉ s ✴ ✁✄✂ ☎✆☎ ❿✁❾ ❿☞➣✬➃ ☎ ❾ → ➄ ➂ ➄ ➃ ➔ ✝ → ➄◆➄ ➅ ➣ ✁ ➂✆✞ ✪ ❇❂✬✛❅❂❊ ✲ s r✕① ➍ ➓ ①✁④ ④ ③ ➇☞①✔➎ ➏ ✦ ➠✠⑥✠✟✡✟ ✉ r✕③☞⑨ ③☞✉ s ①✔⑨ ④✖⑧✕②✕✈ ➐ ✪ ✷ ✹ ✮✭✱✾✫☎✬✯✮☎✳ ✶ ✹ ✮ ✹ ✮ ❆ ✬✯✮❂✷ ❊☞☛❂♦ ✑ ✒✕✚✕✔ ➐ ✚✢✜ ➒ ✥ ➐ ➓

❇✙✷

✶✛✮✴❁ ✷ ✹ ✮✭✱

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✄ ➜ ✄ ✔ ❦ ✺ ✵✯✷ ✳ ✹ ✺ ✱✌❅ ✹ ✶ ✺ ✶ ✹ ✷✰✱✛❋✯✳ ✱✙✮✭✼ ✹ ✬✯✮ ❧ ✫★✭ ➆ ✲ ➢✞✯★✰ ❧ ✲ ➢★✰✞✴ ✪ ✶❂❅✌❅ ✹ ✳ ✹ ✬✯✮✭✶✌✷✛✷ ✹ ✮✭✱❂✼ ✹ ✮ ✺ ✼ ❆ P ✱✛✶❂❅❂✱✌❀✻❅❂✱✯✫✛✷ ✶❂❀ ✱☎✄ ➜ ✄ ✔ ✫☎✬✯✮☎✳ ✱✌✮☎✳ ✳ ❊✛✲✰✱

From: alice@crepes.fr To: bob@hamburger.edu Subject: Picture of yummy crepe. MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Type: image/jpeg base64 encoded data ..... ......................... ......base64 encoded data .

✺ ✵✯✷ ✳ ✹ ✺ ✱✌❅ ✹ ✶❸❅✛✶✴✳ ✶ ✳ ❊✛✲✰✱ ❧ ✼✰✵❂❇✛✳ ❊✛✲☎✱ ❧ ✲✰✶❂❀ ✶ ✺ ✱✯✳ ✱✯❀✻❅✛✱✯✫❂✷ ✶✛❀ ✶✴✳ ✹ ✬✯✮ ✺ ✱✛✳ P ✬✛❅✾✵☎✼✰✱✯❅ ✳ ✬❉✱✌✮✰✫✭✬✛❅✛✱✤❅❂✶✴✳ ✶ ✄ ➜ ✄ ✔ ❄☎✱✯❀ ✼ ✹ ✬✯✮ ✱✌✮✰✫☎✬✛❅❂✱✯❅✤❅❂✶❂✳ ✶

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✚★✧✢✘ ✪ ✱✛❋✯✶ ✺ ✲✯✷ ✱❸✼✰✵❂❇✛✳ ❊✛✲✰✱❂✼✛❦ plain,

html

➏ ◗r✔✌✣✗✚ ✪ ✱✛❋✯✶ ✺ ✲✯✷ ✱❸✼✰✵❂❇✛✳ ❊✛✲✰✱❂✼✛❦ jpeg,

gif

➍ ➙ ➐ ▼ ✥ ✪ ✱✛❋✯✶ ✺ ✲✰✱❉✼✰✵✛❇✛✳ ❊✛✲☎✱✛✼✛❦ basic ➇ ✵ ❍ ❇ ✹ ✳ ✺ ✵✴❍✭✷ ✶❂✿→✱✌✮✰✫☎✬✛❅❂✱✌❅✯➈ ❧

32kadpcm

✌ ✍✏✎✒✑✔✓✖✕✠✗ ✘✠✙✄✚✜✛ ✢✠✣✔✤ ✥ ▼ ➐ ✚✧✥ ✪ ✱✛❋✯✶ ✺ ✲✯✷ ✱❸✼✰✵❂❇✛✳ ❊✛✲✰✱❂✼✛❦ mpeg,

quicktime

➍ ✖✗✖✢✦ ▼ ❏✌✔✌✘✙▼ ✥✕❙ ✪ ✬❂✳ P ✱✯❀✻❅✛✶✴✳ ✶❉✳ P ✶✴✳ ✺ ✵☎✼✴✳❈❇❂✱ ✲❂❀ ✬✯✫✭✱❂✼☎✼☎✱✌❅r❇✴❊❸❀ ✱❂✶✛❅❂✱✯❀ ❇❂✱❂✽✰✬✛❀ ✱ ♠ ❄ ✹ ✱✯✿✕✶✛❇✙✷ ✱✛♥ ✪ ✱✛❋✯✶ ✺ ✲✯✷ ✱❸✼✰✵❂❇✛✳ ❊✛✲✰✱❂✼✛❦

msword, octet-stream

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

➋ ✄ ❼ ➝ ❦✛❅❂✱✙✷ ✹ ❄✭✱✌❀ ❊❂➌☎✼✴✳ ✬✛❀ ✶ ❆ ✱✾✳ ✬✾❀ ✱✯✫✭✱ ✹ ❄✭✱✯❀✄✑ ✼✻✼☎✱✌❀ ❄☎✱✯❀ ✪ ✄❉✶ ✹ ✷✰✶❂✫✴✫✭✱❂✼✰✼●✲❂❀ ✬❂✳ ✬✛✫✭✬✌✷ ❦✛❀ ✱✛✳✰❀ ✹ ✱✛❄✭✶✌✷☎✽❂❀ ✬ ✺ ✼☎✱✯❀✭❄✭✱✯❀ ❃ ➝✗✖❈➝ ❦ ➝ ✬✴✼✰✳ ✖ ✽✰✽ ✹ ✫✭✱ ➝ ❀ ✬❂✳ ✬✛✫✭✬✌✷✧✦ ✫★✭ ➆ ➡ ✮✱➑✞✮✏★ ✩ ✶✴✵✴✳ P ✬✛❀ ✹ ✱ ✶✴✳ ✹ ✬✯✮ ➇ ✶ ❆ ✱✙✮☎✳✫✪ ❍ ❍ ✬ ✼☎✱✯❀✭❄✭✱✯❀☎➈✗✶✛✮✰❅✤❅❂✬❂✿❴✮❂✷ ✬✴✶✛❅ ❃ ➜ ✄ ❥ ➝ ❦ ➜ ✮☎✳ ✱✯❀✰✮✭✱✛✳ ✄❉✶ ✹ ✷ ❥ ✫✰✫✭✱✛✼☎✼ ➝ ❀ ✬❂✳ ✬✛✫✭✬✙✷✭✦ ✫★✭ ➆ ➡ ✮✱➑✯➢✜★ ✩ ✺ ✬✛❀ ✱❸✽✰✱❂✶✴✳✭✵❂❀ ✱❂✼ ➇ ✺ ✬✛❀ ✱✾✫☎✬ ✺ ✲✛✷ ✱✛❋✌➈ ✩ ✺ ✶✛✮ ✹ ✲✴✵✛✷ ✶❂✳ ✹ ✬✯✮✻✬✴✽●✼✰✳ ✬✛❀ ✱✯❅ ✺ ✼ ❆ ✼❈✬✯✮✓✼☎✱✌❀ ❄☎✱✯❀ ✹ ❊ ❂ ✸

❂✄✺ ■ ❊ ❂ ✺ ✘ ❂✄✸ ✯ ❊ ✒✆● ✻ ❀ ❊ ❂ ✸ ❄ ❂✄✸ ✹ ❊ ❂ ✸

❂✄✺ ■ ❧ ■ ➥ ➎ ❧ ■ ➥ ➎ ➎✏✰❘➎ ✯ ✥✗✜ ➏ ■ ➍❸➎ ✸ ❂ ❍ ❂✄✻ ❄ ❂ ✸ ✯ ❊ ✒✆● ✻ ❀ ❊ ❂ ✸ ❄ ❂✄✸

✂☎✄ ✄ ✆ ✝ ✞ ✟ ✠ ✝ ✡ ☛✌☞ ✟ ✍ ✎ ✏

✔✗➙✌✘✌✒✕✥✕✜✌▼

✱✌✔✙✘✙▼ ✥✧❙❘✖✧✒✗✔✙★✯✚ ✪ ✫❂✷ ✹ ✱✌✮☎✳❈✫✭✬ ✺✻✺ ✶✯✮✰❅❂✼✛❦ ❃

user:

❅❂✱✌✫❂✷ ✶✛❀ ✱✾✵✰✼☎✱✯❀✰✮✭✶ ✺ ✱ ❃

pass:

✲✰✶✰✼☎✼✰✿✕✬✛❀☎❅ ✪ ✼☎✱✯❀✭❄✭✱✌❀✻❀ ✱❂✼✴✲✰✬✯✮✭✼☎✱❂✼ ❃

+OK

❃

✘✌✜❂✔✕❙✯★✯✔✙❏✌✘✙▼ ✥✧❙→✖✕✒✕✔✌★✯✚✡☛ ✫✛✷ ✹ ✱✙✮☎✳✴❦ ✪

list:

✷ ✹ ✼✰✳ ✺ ✱✛✼☎✼☎✶ ❆ ✱✤✮☎✵ ✺ ❇❂✱✯❀ ✼ ✪

retr:

❀ ✱✛✳☎❀ ✹ ✱✛❄✭✱ ✺ ✱❂✼☎✼☎✶ ❆ ✱r❇✴❊ ✮☎✵ ✺ ❇✴✱✌❀ ✪

dele:

❅❂✱✗✷ ✱✛✳ ✱ ✪

quit

C: list

S: 1 498 S: 2 912 S: . C: retr 1 S: <message 1 contents> S: . C: dele 1 C: retr 2 S: <message 1 contents> S: . C: dele 2 C: quit S: +OK POP3 server signing off S: +OK POP3 server ready C: user alice S: +OK C: pass hungry S: +OK user successfully logged on