The Internet by Jessica McKellar

Transcript

1. The Internet
   @jessicamckellar
   http://jesstess.com
   

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2. You type http://python.org
   into your browser bar and
   press Enter. What happens?
   

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4. Questions
   What
   Where
   How
   is python.org?
   is python.org?
   does my computer talk to
   python.org?
   does my computer say to
   python.org?
   What
   

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5. Protocol
   A format and rules for
   exchanging information
   

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6. Internet
   protocols
   are layered,
   one protocol
   per task
   

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7. What is python.org?
   Domain Name Service
   (DNS) translates hostnames to
   addresses
   python.org → 82.94.164.162
   

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9. Where is python.org?
   Internet Protocol (IP)
   handles addressing and routing
   

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10. Your packets of data hop from router to router
    through the Internet to their destination
    

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11. scapy demo!
    

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13. >>> res, _ = traceroute("python.org")
    Begin emission:*.*.*.*.*.*.*.*.*.*.*.
    82.94.164.162:tcp80
    1 192.168.1.1
    2 96.120.66.81
    3 68.85.160.37
    4 68.85.106.29
    5 68.86.90.57
    6 68.86.85.22
    7 75.149.228.126
    8 134.222.226.154
    9 134.222.231.148
    10 134.222.231.156
    11 134.222.229.113
    12 134.222.97.18
    13 194.109.5.82
    14 194.109.12.34
    15 82.94.164.162
    >>> res.graph(target="> traceroute.svg")
    openwrt.lan
    96.120.168.1.1
    cambridge.ma.boston.comcast.net
    needham.ma.boston.comcast.net
    newyork.ny.ibone.comcast.net
    111eighthave.ny.ibone.comcast.net
    nyk-s2-rou-1001.us.eurorings.net
    ldn-s2-rou-1101.uk.eurorings.net
    ldn-s1-rou-1021.uk.eurorings.net
    asd2-rou-1022.nl.eurorings.net
    asd2-rou-1044.nl.eurorings.net
    134.222.97.18
    xr4.1d12.xs4all.net
    swcolo2.3d12.xs4all.net
    dinsdale.python.org
    

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14. Me
    python.org
    

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15. Me
    

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18. python.org
    

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19. traceroute_ips = """
    96.120.66.81
    68.85.160.37
    68.85.106.29
    68.86.90.57
    68.86.85.22
    75.149.228.126
    134.222.226.154
    134.222.231.148
    134.222.231.156
    134.222.229.113
    134.222.97.18
    194.109.5.82
    194.109.12.34
    82.94.164.162
    """.strip().split("\n")
    

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20. import pygeoip
    gi = pygeoip.GeoIP("GeoLiteCity.dat")
    for ip in traceroute_ips:
    record = gi.record_by_addr(ip)
    print ip.ljust(15),
    print record["country_name"],
    if record["time_zone"]:
    print record["time_zone"],
    print ""
    

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21. $ python geolocate.py
    96.120.66.81 United States Boston
    68.85.160.37 United States Boston
    68.85.106.29 United States Boston
    68.86.90.57 United States New_York
    68.86.85.22 United States New_York
    75.149.228.126 United States New_York
    134.222.226.154 United Kingdom London
    134.222.231.148 United Kingdom London
    134.222.231.156 Netherlands Amsterdam
    134.222.229.113 Netherlands Amsterdam
    134.222.97.18 Netherlands Amsterdam
    194.109.5.82 Netherlands Amsterdam
    194.109.12.34 Netherlands Amsterdam
    82.94.164.162 Netherlands Amsterdam
    

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22. http://submarinecablemap.com
    

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24. Where is python.org?
    Internet Protocol (IP)
    IP handles addressing and
    routing
    

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25. How does my computer
    talk to python.org?
    Transmission Control
    Protocol (TCP)
    TCP reliably delivers data
    

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27. Application-layer
    protocols that use TCP
    web: HTTP
    chat: IRC, XMPP/Jabber
    email: SMTP, POP3, IMAP
    Each application uses a different “port”
    number, so many different applications can use
    TCP to talk to an IP address at the same time
    

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28. How does my computer
    talk to python.org?
    Transmission Control
    Protocol (TCP)
    TCP reliably delivers data
    

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29. What does my computer
    say to python.org?
    HyperText Transfer
    Protocol (HTTP)
    Clients use HTTP to request
    resources from servers
    

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30. Resources
    • HTML
    • images
    • textual or binary data
    • dynamically-generated query results
    ://python.org
    http
    

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31. How to be a web
    browser
    telnet demo!
    

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33. $ telnet python.org 80
    Trying 82.94.164.162...
    Connected to python.org.
    Escape character is '^]'.
    GET / HTTP/1.1
    Host: python.org
    

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34. HTTP/1.1 200 OK
    Date: Mon, 04 Mar 2013 00:22:30 GMT
    Server: Apache/2.2.16 (Debian)
    Last-Modified: Fri, 01 Mar 2013
    22:31:40 GMT
    Content-Type: text/html
    
    
    Python Programming Language
    – Official Website
    
    
    

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35. HTTP/1.1 200 OK
    Date: Mon, 04 Mar 2013 00:22:30 GMT
    Server: Apache/2.2.16 (Debian)
    Last-Modified: Fri, 01 Mar 2013
    22:31:40 GMT
    Content-Type: text/html
    
    
    Python Programming Language
    – Official Website
    
    
    

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36. HTTP/1.1 200 OK
    Date: Mon, 04 Mar 2013 00:22:30 GMT
    Server: Apache/2.2.16 (Debian)
    Last-Modified: Fri, 01 Mar 2013
    22:31:40 GMT
    Content-Type: text/html
    
    
    Python Programming Language
    – Official Website
    
    
    

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37. HTTP/1.1 200 OK
    Date: Mon, 04 Mar 2013 00:22:30 GMT
    Server: Apache/2.2.16 (Debian)
    Last-Modified: Fri, 01 Mar 2013
    22:31:40 GMT
    Content-Type: text/html
    
    
    Python Programming Language
    – Official Website
    
    
    

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38. HTTP/1.1 200 OK
    Date: Mon, 04 Mar 2013 00:22:30 GMT
    Server: Apache/2.2.16 (Debian)
    Last-Modified: Fri, 01 Mar 2013
    22:31:40 GMT
    Content-Type: text/html
    
    
    Python Programming Language
    – Official Website
    
    
    

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39. import urllib2
    urllib2.urlopen(
    "http://python.org").read()
    HyperText Transfer Protocol
    HyperText Markup Language
    Scrapy: it GETs the Web
    

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40. How to be a
    web server
    

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41. class HTTPProtocol(basic.LineReceiver):
    def __init__(self):
    self.lines = []
    def lineReceived(self, line):
    self.lines.append(line)
    if not line:
    self.sendResponse()
    def sendResponse(self):
    self.sendLine("HTTP/1.1 200 OK")
    self.sendLine("")
    for line in self.lines:
    self.sendLine(line)
    self.transport.loseConnection()
    reactor.listenTCP(80, HTTPFactory())
    reactor.run()
    Twisted HTTP
    echo server
    

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42. class HTTPProtocol(basic.LineReceiver):
    def __init__(self):
    self.lines = []
    def lineReceived(self, line):
    self.lines.append(line)
    if not line:
    self.sendResponse()
    def sendResponse(self):
    self.sendLine("HTTP/1.1 200 OK")
    self.sendLine("")
    for line in self.lines:
    self.sendLine(line)
    self.transport.loseConnection()
    reactor.listenTCP(80, HTTPFactory())
    reactor.run()
    

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43. GET / HTTP/1.1
    Host: localhost:80
    Connection: keep-alive
    Accept: text/html,application/xhtml
    +xml,application/xml;q=0.9,*/*;q=0.8
    User-Agent: Mozilla/5.0 (Macintosh;
    Intel Mac OS X 10_8_2) AppleWebKit/
    537.17 (KHTML, like Gecko) Chrome/
    24.0.1312.57 Safari/537.17
    Accept-Encoding: gzip,deflate,sdch
    Accept-Language: en-US,en;q=0.8
    Accept-Charset:
    ISO-8859-1,utf-8;q=0.7,*;q=0.3
    What your
    browser sends
    web servers
    

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44. What does my computer
    say to python.org?
    HyperText Transfer
    Protocol (HTTP)
    Clients use HTTP to request
    resources from servers
    

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45. You type http://python.org
    into your browser bar and
    press Enter. What happens?
    

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46. IP IP
    TCP TCP
    HTTP HTTP
    addressing and routing
    reliable delivery
    requesting resources
    DNS DNS
    hostnames → IP addresses
    

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47. 
    

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49. Surfing the web
    protocol
    source IP
    destination IP protocol data
    

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50. Lonely printers
    source IP
    destination IP
    protocol
    protocol data
    

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51. Lonely TiVos
    

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52. Errors
    TCP protocol,
    retransmitting lost data
    

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53. Encrypted communication
    source IP
    destination IP
    protocol
    protocol data
    

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54. IRC
    

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55. IRC
    IRC server
    prompting
    for a
    password
    

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56. IRC
    My password, django4life
    

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57. 
    

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58. One last demo
    How to propose marriage
    on your local network
    using Scapy and ARP-cache
    poisoning
    

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59. Lonely printers
    Address Resolution
    Protocol (ARP) maps hardware
    (MAC) addresses to IP addresses
    

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61. What next?
    •Twisted (visit me at the Expo
    Hall!)
    •Scapy
    •wireshark
    

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62. @jessicamckellar
    http://jesstess.com
    Thank you!
    

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63. A map of the entire Internet in 1977
    

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