From last class: Routing 2

My computer -> www.sfc.keio.ac.jp

My computer ---> router in studio art building closet ---> router at edge of Reed network ---> router at network provider...




Looking up routing table using a UNIX command
%netstat -r
Routers know a lot - it's kind of like a station in the Yellow line knowing every station on the yellow line.

Packet forwarding

Notes

Packet forwarding gone wrong

Notes

TTL and traceroute

To prevent infinite loops, limit the lifespan of packets

Traceroute

Notes

traceroute

On the Terminal.app
% traceroute www.sfc.keio.ac.jp
     traceroute to www.sfc.keio.ac.jp (133.27.4.221), 64 hops max, 52 byte packets
 1  clarkacad (134.10.2.44)  1.214 ms  0.926 ms  1.340 ms
 2  borderrouter (134.10.64.2)  0.909 ms  0.863 ms  0.731 ms
 3  206-169-234-117.static.twtelecom.net (206.169.234.117)  0.943 ms  0.914 ms  0.863 ms
 4  64-129-238-138.static.twtelecom.net (64.129.238.138)  15.637 ms  15.664 ms  15.670 ms
 5  te-9-4.car1.sanjose2.level3.net (4.59.0.229)  15.884 ms  15.819 ms  15.853 ms
 6  vlan80.csw3.sanjose1.level3.net (4.69.152.190)  16.005 ms  18.096 ms  24.721 ms
 7  ae-81-81.ebr1.sanjose1.level3.net (4.69.153.9)  16.337 ms  16.031 ms  15.975 ms
 8  ae-2-2.ebr3.losangeles1.level3.net (4.69.132.10)  23.428 ms  23.507 ms  24.543 ms
 9  ae-93-93.csw4.losangeles1.level3.net (4.69.137.46)  23.420 ms
    ae-73-73.csw2.losangeles1.level3.net (4.69.137.38)  32.388 ms
    ae-83-83.csw3.losangeles1.level3.net (4.69.137.42)  28.521 ms
10  ae-1-60.edge5.losangeles1.level3.net (4.69.144.11)  23.699 ms
    ae-3-80.edge5.losangeles1.level3.net (4.69.144.139)  23.449 ms
    ae-4-90.edge5.losangeles1.level3.net (4.69.144.203)  23.646 ms
11  japan-telec.edge5.losangeles1.level3.net (4.59.48.2)  23.209 ms  23.487 ms  23.497 ms
12  tokyo-dc-gm2-xe5-3-2-vlan10.s4.sinet.ad.jp (150.99.2.81)  136.906 ms  136.761 ms
    tokyo-dc-gm2-xe4-3-0-vlan10.s4.sinet.ad.jp (150.99.2.77)  164.841 ms
13  tokyo-dc-rm-ae4-vlan10.s4.sinet.ad.jp (150.99.2.53)  151.746 ms  137.422 ms  137.273 ms
14  keio.gw.sinet.ad.jp (150.99.188.18)  153.990 ms  141.243 ms  141.152 ms
15  bb-sfc-core0-hc.bb.keio.ac.jp (131.113.1.166)  151.238 ms  151.232 ms  151.367 ms
16  fw1-entry-sfc.bb.keio.ac.jp (131.113.255.78)  126.761 ms  139.489 ms  139.620 ms
17  gw2.sfc.keio.ac.jp (133.27.3.1)  140.368 ms  152.952 ms  139.885 ms
18  www.sfc.keio.ac.jp (133.27.4.221)  140.742 ms  153.864 ms  140.836 ms
    
Hit Ctrl-C to stop.
Notes

traceroute 2

If a packet is not acknowledged within the expected timeout, an asterisk is displayed.

traceroute to www.amazon.com (72.21.211.176), 64 hops max, 52 byte packets
 1  clarkacad (134.10.2.44)  1.196 ms  1.059 ms  1.013 ms
 2  borderrouter (134.10.64.2)  0.801 ms  0.947 ms  0.854 ms
 3  206-169-234-117.static.twtelecom.net (206.169.234.117)  0.884 ms  5.872 ms  1.154 ms
 4  sea2-pr2-xe-1-3-0-0.us.twtelecom.net (66.192.253.122)  4.654 ms  4.574 ms  4.556 ms
 5  64.132.69.202 (64.132.69.202)  4.502 ms  4.342 ms  4.388 ms
 6  dca2-edge-01.inet.qwest.net (67.14.28.110)  77.527 ms  78.077 ms  77.656 ms
 7  72.165.86.74 (72.165.86.74)  78.548 ms  78.287 ms  78.247 ms
 8  72.21.220.157 (72.21.220.157)  79.836 ms  87.652 ms
    72.21.220.125 (72.21.220.125)  80.156 ms
 9  72.21.222.147 (72.21.222.147)  84.281 ms  114.044 ms  78.168 ms
10  72.21.218.13 (72.21.218.13)  80.088 ms  79.859 ms  79.559 ms
11  * * *
12  * * *
13  * * *
14  * * *
15  * * *
16  * * *
17  * * *
18  * * *
19  * * *

    
Notes

UNIX Commands

basic convention used in many UNIX commands:
Ctrl-C            // quit program


man : getting help (manual)
% man man 
% man traceroute


   Space key         // continue scrolling when viewing "man" or using "less"
   b                 // go backward when viewing "man" or using "less"
   q                 // go backward when viewing "man" or using "less"





I will talk about this in future class
ls : list files

  % ls
  % ls -l
  % ls -a

cd : change directory (folder)

  % cd
  % cd ..               // move up one directory (.. means up)
  % cd ~                // move to home ~ means home
  % cd ~/Documents/     // move to Documents folder under home
  % cd ~/Documents/Processing    
  % cd ~/Documents/Processing/   // the final "/" makes it explicit that it is a directory    
  % cd ../../../        // move three directory up
  % cd .                // . means "here" 

pwd : display present working directory


cp : copy file

% cp file1 file2      // copy file1 to file 2
% cp ~/Desktop/test.txt foo.txt
% cp ~/Desktop/test.txt ~/Documents/

mv : move file

% mv file1 file2           // move file1 to file 2
% mv file1 html/lecture/   // move file1 to directory lecture




Other UNIX commands you might want to take a look at
netstat, less, cat, ssh, telnet, sftp, find, gzip, rm, mkdir, rmdir, wc, diff, grep, w, finger, whoami, ps, kill, last...

Some links from the Internet:
Unix Command Summary
Basic UNIX commands
Introduction to Unix commands
Notes

Traceroute assignment

Traceroute assignment: ping, dig, traceroute, whois, and an open-ended question
Notes