CS 145A Implementation Issues Netlab.caltech.edu/course

Topics of this thread How does the TCP/IP work? (roughly) How does the TCP/IP work? (roughly) (Very) Simple & basic tools on network engineering (Very) Simple & basic tools on network engineering Design and implementation of protocols Design and implementation of protocols

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Today The topology of Internet The topology of Internet Naming Naming Packet transmission Packet transmission Stream Connection Stream Connection

What does the Internet look like? Example: (/sbin/traceroute) Example: (/sbin/traceroute) C:\>tracert cwis.usc.edu Tracing route to cwis.usc.edu [ ] 1 <1 ms Jorgensen-RSM-44.caltech.edu [ ] 2 <1 ms Booth-border.ilan.caltech.edu [ ] 3 <1 ms CalREN-Caltech.caltech.edu [ ] 4 <1 ms JPL--CIT.POS.calren2.net [ ] 5 1 ms UCLA--JPL.POS.calren2.net [ ] 6 1 ms ISI--UCLA.POS.calren2.net [ ] 7 2 ms USC--ISI.POS.calren2.net [ ] 8 3 ms rtr43-c2-gw.usc.edu [ ] 9 2 ms rtr-gw-1.usc.edu [ ] 10 2 ms cwis.usc.edu [ ]

Topology of the Network

Global Network (From Quest)

Get your “ IDs ” on-line Example: (/sbin/ifconfig) Example: (/sbin/ifconfig) C:\>ipconfig – all Physical Address : A4-79-F0-32 IP Address : Subnet Mask :

Use of the IDs Application TCP/UDP IP MAC Physic

The Journey of a packet (1) Application : Send [MSG] to “ : 5001 ” UDP IP MAC Physic

The Journey of a packet (1) Application : Send [MSG] to “ : 5001 ” UDP UDP header + [MSG] Send to IP MAC Physic

The Journey of a packet (1) Application : Send [MSG] to “ : 5001 ” UDP UDP header + [MSG] Send to IP IP header + UDP header + [MSG] Send to (from routing table) Send to 00:90:6D:E7:D4:00 (from ARP) MAC Physic

The Journey of a packet (1) Application : Send [MSG] to “ : 5001 ” UDP UDP header + [MSG] Send to IP IP header + UDP header + [MSG] Send to (from routing table) Send to 00:90:6D:E7:D4:00 (from ARP) MAC MAC header + IP + UDP + [MSG] Physic

The Journey of a packet (1) Application : Send [MSG] to “ : 5001 ” UDP UDP header + [MSG] Send to IP IP header + UDP header + [MSG] Send to (from routing table) Send to 00:90:6D:E7:D4:00 (from ARP) MAC MAC header + IP + UDP + [MSG] Physic Send to the Ethernet

The Journey of a packet (1) >

The Journey of a packet (2) IP MAC Physic Get a packet From Ethernet It ’ s for 00:90:6D:E7:D4:00. That ’ s me. I should accept it.

The Journey of a packet (2) IP MAC “ OK, I am 00:90:6D:E7:D4:00 ” Pass the packet to IP Physic Get a packet from ethernet for : 00:90:6D:E7:D4:00

The Journey of a packet (2) IP [IP] Header: From to “ ” “ Should go to next router: ” MAC “ OK, I am 00:90:6D:E7:D4:00 ” Pass the packet to IP Physic Get a packet from ethernet for: 00:90:6D:E7:D4:00

The Journey of a packet (2) IP [IP] Header: From to “ ” “ Should go to next router: ” Send to zz:zz:zz:zz:zz:zz (from ARP) MAC Physic

The Journey of a packet (2) IP [IP] Header: From to “ ” “ Should go to next router: ” Send to zz:zz:zz:zz:zz:zz (from ARP) MAC MAC header + IP + UDP + [MSG] Physic

The Journey of a packet (2) IP [IP] Header: From to “ ” “ Should go to next router: ” Send to zz:zz:zz:zz:zz:zz (from ARP) MAC MAC header + IP + UDP + [MSG] Physic Send to zz:zz:zz:zz:zz:zz

The Journey of a packet (2) >

The Journey of a packet (n) >

The Journey of a packet (n) Application “ I want to receive something on port 5001 ” UDP Listening to the port 5001 IP MAC Physic

The Journey of a packet (n) Application UDP Listening to the Port 5001 IP MAC Physic Get a packet from ethernet for yy:yy:yy:yy:yy:yy

The Journey of a packet (n) Application UDP Listening to the Port 5001 IP MAC “ Yes, I am yy:yy:yy:yy:yy:yy ” Pass the packet to IP Physic Get a packet From ethernet for yy:yy:yy:yy:yy:yy

The Journey of a packet (n) Application UDP Listening to port 5001 IP From to :5001 “ Yes, I am ” “ Is there any program listening to this port? ” “ Yes. One UDP is waiting. Pass it to UDP ” MAC “ Yes, I am yy:yy:yy:yy:yy:yy ” Pass the packet to IP Physic Get a packet From ethernet for yy:yy:yy:yy:yy:yy

The Journey of a packet (n) Application Receive message from UDP Pass to Application IP From to “ Yes, I am ” “ Is there any program waiting for it? ” “ Yes. One application is waiting. Pass it to UDP ” MAC “ Yes, I am yy:yy:yy:yy:yy:yy ” Pass the packet to IP Physic Get a packet From Ethernet For yy:yy:yy:yy:yy:yy

Overview

Necessary Information (1) Where shall I pass the packet, for a given destination IP address? – Routing Table Where shall I pass the packet, for a given destination IP address? – Routing Table Exmaple: Exmaple: route DestinationGatewayGen-maskFlagsInterface * UEth * Ulo default UFEth0

Necessary Information (2) Where shall I pass the packet, for a given destination IP address? -- Arp Where shall I pass the packet, for a given destination IP address? -- Arp Exmaple: Exmaple: arp -a at 00:06:5B:DE:C5:72 on eth at 00:60:B0:7C:E8:02 on eth at 00:A0:C9:5A:26:6D on eth at 00:E0:81:02:7F:7B on eth at 00:00:0C:07:AC:01 on eth at 00:90:6D:E7:D4:00 on eth at 00:20:78:1B:13:2C on eth at 00:A0:C9:06:2F:2A on eth0

More Information (Bonus) Get your phone book (Domain Name Service). Get your phone book (Domain Name Service). Example: Example: ping login.cs.caltech.edu PING orchestra.cs.caltech.edu ( ) from : 56(84) bytes of data. freebsd- login.cs.caltech.edu ( ) API: API:gethostbyname()

How does DNS work?

Connection

Streamless Connection ApplicationSocket_send/receiveDNS UDP UDP send/receive IP Routing (IP / ARP) MAC Ethernet or other LAN Physic Electronic/Optical signals

Stream Connection ApplicationSocket_send/receiveDNS TCP How to establish/maintain a connection? IP Routing (IP / ARP) MAC Ethernet/Token Ring or other direct links Physic Electronic/Optical signals

Stream Connection An Example: At: Call: DMV An Example: At: Call: DMV Prerequisite: Prerequisite: You know the number of DMV ( ) You know the number of DMV ( ) The service is now open at DMV. The service is now open at DMV. There is a link between the two phones. There is a link between the two phones.

Stream Connection Steps at your site: Establish the phone Establish the phone Dial the number Dial the number Select the service Select the service Talk Talk Hang up Hang up Steps at DMV: Establish the phone Establish the service on phone Accept your request Talk Hang Up An Example: At: Call: DMV An Example: At: Call: DMV

Stream Connection Steps at DMV: Establish the phone Establish the phone Establish the service on phone Establish the service on phone Accept your request Accept your request Talk to you Talk to you Hang Up Hang Up Steps at your site: Establish the phone Establish the phone Dial the number Dial the number Select the service Select the service Talk to the representative Talk to the representative Hang up Hang up

Stream Connection Steps at client’s site: Establish the socket Establish the socket Dial the number Dial the number Select the service Select the service Talk to the representative Talk to the representative Hang up Hang up Steps at server’s site: Establish the socket Establish the service Accept your request Talk to you Hang Up Steps at DMV: Establish the phone Establish the phone Establish the service on phone Establish the service on phone Accept your request Accept your request Talk to you Talk to you Hang Up Hang Up Steps at your site: Establish the phone Establish the phone Dial the number Dial the number Select the service Select the service Talk to the representative Talk to the representative Hang up Hang up

Stream Connection Steps at client’s site: Establish the socket Establish the socket Dial the number Dial the number Select the service Select the service Talk to the representative Talk to the representative Hang up Hang up Steps at server’s site: Establish the socket Bind socket to port & Listen Accept your request Talk to you Hang Up Steps at client’s site: Establish the socket Establish the socket Dial the number Dial the number Select the service Select the service Talk to the representative Talk to the representative Hang up Hang up Steps at server’s site: Establish the socket Establish the socket Establish the service on phone Establish the service on phone Accept your request Accept your request Talk to you Talk to you Hang Up Hang Up

Stream Connection Steps at client’s site: Establish the socket Establish the socket connect the address ( IP connect the address ( IP + port ) + port ) Talk to the representative Talk to the representative Hang up Hang up Steps at server’s site: Establish the socket Bind socket to a port & Listen Accept your request Talk to you Hang Up Steps at client’s site: Establish the socket Establish the socket Dial the number Dial the number Select the service Select the service Talk to the representative Talk to the representative Hang up Hang up Steps at server’s site: Establish the socket Establish the socket Bind socket to a port & Listen Bind socket to a port & Listen Accept your request Accept your request Talk to you Talk to you Hang Up Hang Up

Stream Connection Steps at client’s site: Establish the socket Establish the socket connect the address ( IP connect the address ( IP + port ) + port ) Talk Talk Hang up Hang up Steps at server’s site: Establish the socket Bind socket to a port & Listen Accept the request from client Talk to you Hang Up Steps at client’s site: Establish the socket Establish the socket connect the address ( IP connect the address ( IP + port ) + port ) Talk to the representative Talk to the representative Hang up Hang up Steps at server’s site: Establish the socket Establish the socket Bind socket to a port & Listen Bind socket to a port & Listen Accept your request Accept your request Talk to you Talk to you Hang Up Hang Up

Stream Connection Steps at client’s site: Establish the socket Establish the socket connect the address ( IP connect the address ( IP + port ) + port ) Send/Receive Data Send/Receive Data Hang up Hang up Steps at server’s site: Establish the socket Bind socket to a port & Listen Accept the request from client Send/Receive Data Hang Up Steps at client’s site: Establish the socket Establish the socket connect the address ( IP connect the address ( IP + port ) + port ) Talk Talk Hang up Hang up Steps at server’s site: Establish the socket Establish the socket Bind socket to a port & Listen Bind socket to a port & Listen Accept the request from client Accept the request from client Talk to you Talk to you Hang Up Hang Up

Stream Connection Steps at client’s site: Establish the socket Establish the socket connect the address ( IP connect the address ( IP + port ) + port ) Send/Receive Data Send/Receive Data Hang up Hang up Steps at server’s site: Establish the socket Bind socket to a port & Listen Accept the request from client Send/Receive Data Hang Up Steps at client’s site: Establish the socket Establish the socket connect the address ( IP connect the address ( IP + port ) + port ) Send/Receive Data Send/Receive Data Hang up Hang up Steps at server’s site: Establish the socket Establish the socket Bind socket to a port & Listen Bind socket to a port & Listen Accept the request from client Accept the request from client Send/Receive Data Send/Receive Data Hang Up Hang Up

Insight (from LinuxForum)

CS 145A Lab 1 Connection Netlab.caltech.edu/course

How to establish a connection? UDP UDP Steps at client’s site: Establish the socket Establish the socket Send Data to the address ( IP Send Data to the address ( IP + port ) + port ) Close the socket Close the socket Steps at server’s site: Establish the socket Establish the socket Bind socket to a port Bind socket to a port Receive Data Receive Data Close the socket Close the socket

How to establish a connection? TCP TCP Steps at client’s site: Establish the socket Establish the socket connect the address ( IP connect the address ( IP + port ) + port ) Send/Receive Data Send/Receive Data Close the socket Close the socket Steps at server’s site: Establish the socket Establish the socket Bind socket to a port & Listen Bind socket to a port & Listen Accept the request from client and create a new socket for communication Accept the request from client and create a new socket for communication Send/Receive Data on the new socket Send/Receive Data on the new socket Close the socket Close the socket

Tasks for Lab 1 Be familiar with the basic commands that we talked about in class (see those examples in the lecture). Be familiar with the basic commands that we talked about in class (see those examples in the lecture). Write a program ( “ server ” ) that can act as a Server Write a program ( “ server ” ) that can act as a Server Write a program ( “ udp client ” ) that can send UDP packets Write a program ( “ udp client ” ) that can send UDP packets Write a program ( “ tcp client ” ) that can send TCP packets Write a program ( “ tcp client ” ) that can send TCP packets

Server accept TCP connections in one port accept TCP connections in one port The server should “ talk ” with the clients. That is, the server return the same contents as the client sends to it. If the client does not send anything in 10 seconds, the server should actively disconnect the connection. The server should “ talk ” with the clients. That is, the server return the same contents as the client sends to it. If the client does not send anything in 10 seconds, the server should actively disconnect the connection. The server is able to “ talk ” with 5 different clients at the same time. The server should not keep more than 5 clients at the same time. The server is able to “ talk ” with 5 different clients at the same time. The server should not keep more than 5 clients at the same time.

Server accept UDP packets in one port (may be different from the TCP) accept UDP packets in one port (may be different from the TCP) The server should talk to the clients. The server should talk to the clients. The input format: Server Server (port 1 is for TCP, port2 is for UDP)

Tcp client send a message to the server, wait for several seconds, then disconnect. send a message to the server, wait for several seconds, then disconnect. Input format: tcpclient tcpclient is a number indicating the seconds the client should wait before disconnection. is a number indicating the seconds the client should wait before disconnection.

Udp client send a message to the server send a message to the server Input format: udpclient udpclient

Tips For the unknown commands, use “ man ” / “ info ” /Richard Stevens ’ book For the unknown commands, use “ man ” / “ info ” /Richard Stevens ’ book Testing: you can use “ telnet ” to test the server, use the server to test the clients. Testing: you can use “ telnet ” to test the server, use the server to test the clients. How to implement the “ disconnection after 10-sec? ” How to implement the “ disconnection after 10-sec? ” 1. Child-process 2. “ select ” 3. …

Submission (due Oct 18 th ) Task 1: route.txt arp.txt ifconfig.txt traceroute.txt Task 2: server.c; server.txt Task 3: udpclient.c; udpclient.txt Task 4: tcpclient.c; tcpclient.txt Mailto: (Do NOT send to ) Documents:  How to use the program: compile, run …  Your design, your testing, the problems you met  Any other comments

Grading Correctness (70%) Correctness (70%) Documentation and comments (20%) Documentation and comments (20%) Program style (10%) Program style (10%) TA Hours Tue: 20:00 ~22:00 JRG 154 / 170 Tue: 20:00 ~22:00 JRG 154 / 170 Thu: 20:00 ~22:00 JRG 154 / 170 Thu: 20:00 ~22:00 JRG 154 / 170