Advanced Computer Science

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    HistoryEdited Sep 22, 2014 9:46 AM by admin…

    week 6 notes: web servers, ports, routers

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    /groups/advancedcomputerscience/search/index.rss?tag=hotlist/groups/advancedcomputerscience/search/?tag=hotWhat’s HotHotListHot!?tag=hot1/groups/advancedcomputerscience/sidebar/HotListairport extreme setup pagesadminadmin2014-09-22 19:45:24+00:002014-09-22 19:45:24updated4Added tag - hotadminadmin2014-09-22 19:45:23+00:002014-09-22 19:45:23addTag3adminadmin2014-09-22 19:45:09+00:002014-09-22 19:45:09updated2First createdadminadmin2014-09-22 19:38:45+00:002014-09-22 19:38:45created1wiki2014-09-22T19:45:24+00:00groups/advancedcomputerscience/wiki/0554cFalseairport setup pages/groups/advancedcomputerscience/wiki/0554c/airport_setup_pages.htmladmin4 updatesairport setup pages Basic Airport extreme setup pages, using utility 6.3.2 Basic config screen, notice MAC addresses of clients: [Screen Shot 2014-09-...Falseadmin2014-09-22T19:45:24+00:00hot/groups/advancedcomputerscience/search/index.rss?sort=modifiedDate&kind=all&sortDirection=reverse&excludePages=wiki/welcomelist/groups/advancedcomputerscience/search/?sort=modifiedDate&kind=all&sortDirection=reverse&excludePages=wiki/welcomeRecent ChangesRecentChangesListUpdates?sort=modifiedDate&kind=all&sortDirection=reverse&excludePages=wiki/welcome0/groups/advancedcomputerscience/sidebar/RecentChangesListmodifiedDateallRecent ChangesRecentChangesListUpdateswiki/welcomeNo recent changes.reverse5search
    Review:
    IP masquerading
    routers vs. gateways
    apache web server startup
    dhcp vs. static addresses
    ports: 80
    html basics: index.html is the default page on web servers
    (later: much more on servers, ports, html and net neutrality)

    Ports: computer "doors"
    portscan: what doors are available
    Port 80: default web server port
    test on your network with 127.0.0.1 and your 10.14.8.x address
    try with the 80 and without

    portscan:
    use IPNM to test yours, and others
    test physics.hpa.edu
    test 10.14.4.32-who is this? how could you find out? try dns 10.14.1.1

    router setup:
    Airport extreme defaults to DHCP (dynamic host configuration protocol)
    how is this different from static? why is it useful? where would I find it?
    two sides to every gateway/router: the WAN side (wide area network=outside) and the LAN side (inside)
    We will setup your routers to pass traffic from the HPA LAN (our WAN) to your private LAN (192.168.1.x). This means only YOUR computer, not the shared switch on your desktop. Why?
    How will you know it is working?

    See previous weblog for router setup notes, as well as the wiki here:


    "DHCP wired" location, wireless disabled, can you browse the web?
    Look at the settings the router gave you...
    Your mind is probably constructing network diagrams, try writing these down. It's what I use to fall asleep at times...
    Try now with a static address (static and DHCP can co-exist, but you can only have one DHCP server on the LAN)
    Try either a 192.168.1.x address (your crossover network setting)
    You will have to make sure the router is giving out addresses on the 192.168.1.x network.
    NAT and Port forwarding (also known as inbound port mapping).

    NAT: your computer uses the router to translate your address into a web request to the server, which then passes the response back to you, Network address translation (NAT)

    Port forwarding/inbound port mapping: calls to the outside WAN side of the router are passed to some FIXED address on the LAN.
    You have to have a fixed address on the LAN for the router to know who to send the packet to.

    Test this on your private network with your apache web server.

    Play around with this in the class, looking for others' routers, and your web server
    You can also look under Utilities for Activity monitor, it should show folks looking at your web page
    If you are really curious, you can go to console and see who exactly is looking at your web pages...
    (look into the tail -f command for future reference)

    Next steps: port forward 548, 22 and others...what do you see?
    How could this be useful at your home/dorm?

    b