cs 145a implementation issues

CS 145ACS 145AImplementation Implementation

IssuesIssuesNetlab.caltech.edu/courseNetlab.caltech.edu/course

Topics of this threadTopics of this thread

How does the TCP/IP work? How does the TCP/IP work? (roughly)(roughly)

(Very) Simple & basic tools on (Very) Simple & basic tools on network engineeringnetwork engineering

Design and implementation of Design and implementation of protocolsprotocols

Mail listsMail lists

CS145class.cs.caltech.eduCS145class.cs.caltech.edu CS145ta.cs.caltech.eduCS145ta.cs.caltech.edu

TodayToday

The topology of InternetThe topology of Internet NamingNaming Packet transmissionPacket transmission Stream ConnectionStream Connection

What does the Internet What does the Internet look like?look like?

Example: (/sbin/traceroute) Example: (/sbin/traceroute) C:\>tracert cwis.usc.eduC:\>tracert cwis.usc.eduTracing route to cwis.usc.edu [128.125.253.146]Tracing route to cwis.usc.edu [128.125.253.146]1 <1 ms Jorgensen-RSM-44.caltech.edu [131.215.44.253]1 <1 ms Jorgensen-RSM-44.caltech.edu [131.215.44.253]2 <1 ms Booth-border.ilan.caltech.edu [131.215.254.254]2 <1 ms Booth-border.ilan.caltech.edu [131.215.254.254]3 <1 ms CalREN-Caltech.caltech.edu [192.41.208.49]3 <1 ms CalREN-Caltech.caltech.edu [192.41.208.49]4 <1 ms JPL--CIT.POS.calren2.net [198.32.248.5]4 <1 ms JPL--CIT.POS.calren2.net [198.32.248.5]5 1 ms UCLA--JPL.POS.calren2.net [198.32.248.1]5 1 ms UCLA--JPL.POS.calren2.net [198.32.248.1]6 1 ms ISI--UCLA.POS.calren2.net [198.32.248.29]6 1 ms ISI--UCLA.POS.calren2.net [198.32.248.29]7 2 ms USC--ISI.POS.calren2.net [198.32.248.25]7 2 ms USC--ISI.POS.calren2.net [198.32.248.25]8 3 ms rtr43-c2-gw.usc.edu [128.125.251.66]8 3 ms rtr43-c2-gw.usc.edu [128.125.251.66]9 2 ms rtr-gw-1.usc.edu [128.125.254.1]9 2 ms rtr-gw-1.usc.edu [128.125.254.1]10 2 ms cwis.usc.edu [128.125.253.146]10 2 ms cwis.usc.edu [128.125.253.146]

Topology of the NetworkTopology of the Network

131.215.44.214

131.215.44.253

131.215.254.254

192.41.

208.49

198.32.

248.5198.32.

248.1198.32.

248.29

198.32.

248.25

128.125.251.66

128.125.253.146

128.125.254.1

Global Network (From Global Network (From Quest)Quest)

Get your “IDs” on-lineGet your “IDs” on-line

Example: (/sbin/ifconfig)Example: (/sbin/ifconfig)C:\>ipconfig –allC:\>ipconfig –allPhysical Address. . . . . . . . . : 00-10-A4-7Physical Address. . . . . . . . . : 00-10-A4-7

9-F0-329-F0-32IP Address. . . . . . . . . . . . : 131.215.44.214IP Address. . . . . . . . . . . . : 131.215.44.214Subnet Mask . . . . . . . . . . . : 255.255.255.Subnet Mask . . . . . . . . . . . : 255.255.255.

00

Use of the IDsUse of the IDs

ApplicationApplication

TCP/UDPTCP/UDP

IPIP

MACMAC

PhysicPhysic

Physical Address00-10-A4-79-F0-32

I P Address131.215.44.214

ARP

Port Number80 / 23 / ...

The Journey of a packet (1)The Journey of a packet (1)131.215.44.214131.215.44.214

ApplicatioApplicationn

131.215.44.214:131.215.44.214:

Send [MSG] to “128.125.253.146 Send [MSG] to “128.125.253.146 : 5001”: 5001”

UDPUDP

IPIP

MACMAC

PhysicPhysic

131.215.44.214

131.215.44.253

131.215.254.254



131.215.44.214:131.215.44.214:


UDPUDP UDP header + [MSG]UDP header + [MSG]

Send to 128.125.253.146Send to 128.125.253.146

IPIP

MACMAC

PhysicPhysic

131.215.44.214

131.215.44.253

131.215.254.254



131.215.44.214:131.215.44.214:



Send to 128.125.253.146Send to 128.125.253.146

IPIP IP header + UDP header + IP header + UDP header + [MSG][MSG]

Send to 131.215.44.253 (from Send to 131.215.44.253 (from routing table)routing table)

Send to 00:90:6D:E7:D4:00 Send to 00:90:6D:E7:D4:00 (from ARP)(from ARP)

MACMAC

PhysicPhysic

131.215.44.214

131.215.44.253

131.215.254.254



131.215.44.214:131.215.44.214:



Send to 128.125.253.146Send to 128.125.253.146




MACMAC MAC header + IP + UDP + MAC header + IP + UDP + [MSG][MSG]

PhysicPhysic

131.215.44.214

131.215.44.253

131.215.254.254



131.215.44.214:131.215.44.214:



Send to 128.125.253.146Send to 128.125.253.146




MACMAC MAC header + IP + UDP + MAC header + IP + UDP + [MSG][MSG]

PhysicPhysic Send to the EthernetSend to the Ethernet

131.215.44.214

131.215.44.253

131.215.254.254

The Journey of a packet (1)The Journey of a packet (1)131.215.44.214-131.215.44.214->131.215.44.253>131.215.44.253

131.215.44.214

131.215.44.253

131.215.254.254

192.41.

208.49

198.32.

248.5198.32.

248.1198.32.

248.29

198.32.

248.25

128.125.251.66

128.125.253.146

128.125.254.1


IPIP

MACMAC

PhysicPhysic Get a packet From EthernetGet a packet From Ethernet

It’s for 00:90:6D:E7:D4:00. It’s for 00:90:6D:E7:D4:00.

That’s me. I should accept it.That’s me. I should accept it.

131.215.44.214

131.215.44.253

131.215.254.254


IPIP

MACMAC ““OK, I am 00:90:6D:E7:D4:00”OK, I am 00:90:6D:E7:D4:00”

Pass the packet to IPPass the packet to IP

PhysicPhysic Get a packet from ethernet for : 00:Get a packet from ethernet for : 00:90:6D:E7:D4:0090:6D:E7:D4:00

131.215.44.214

131.215.44.253

131.215.254.254


IPIP [IP] Header: [IP] Header:

From 131.215.44.214 to From 131.215.44.214 to “128.125.253.146”“128.125.253.146”

““Should go to next router: Should go to next router: 131.215.254.254”131.215.254.254”

MACMAC ““OK, I am 00:90:6D:E7:D4:00”OK, I am 00:90:6D:E7:D4:00”

Pass the packet to IPPass the packet to IP

PhysicPhysic Get a packet from ethernet for: 00:Get a packet from ethernet for: 00:90:6D:E7:D4:0090:6D:E7:D4:00

131.215.44.214

131.215.44.253

131.215.254.254

The Journey of a packet (2)The Journey of a packet (2) 131.215.44.253 131.215.44.253

IPIP [IP] Header: [IP] Header: From 131.215.44.214 to “128.125.2From 131.215.44.214 to “128.125.2

53.146”53.146”““Should go to next router: 131.215.Should go to next router: 131.215.

254.254”254.254”Send to zz:zz:zz:zz:zz:zz (from ARSend to zz:zz:zz:zz:zz:zz (from AR

P)P)MACMAC

PhysicPhysic

131.215.44.214

131.215.44.253

131.215.254.254





P)P)MACMAC MAC header + IP + UDP + MAC header + IP + UDP +

[MSG][MSG]

PhysicPhysic

131.215.44.214

131.215.44.253

131.215.254.254





P)P)MACMAC MAC header + IP + UDP + MAC header + IP + UDP +

[MSG][MSG]

PhysicPhysic Send to zz:zz:zz:zz:zz:zzSend to zz:zz:zz:zz:zz:zz

131.215.44.214

131.215.44.253

131.215.254.254

The Journey of a packet (2)The Journey of a packet (2)131.215.44.253-131.215.44.253-

>131.215.254.254>131.215.254.254131.215.44.214

131.215.44.253

131.215.254.254

192.41.

208.49

198.32.

248.5198.32.

248.1198.32.

248.29

198.32.

248.25

128.125.251.66

128.125.253.146

128.125.254.1

The Journey of a packet (n) The Journey of a packet (n) 128.125.254.1-128.125.254.1-

>128.125.253.146>128.125.253.146131.215.44.214

131.215.44.253

131.215.254.254

192.41.

208.49

198.32.

248.5198.32.

248.1198.32.

248.29

198.32.

248.25

128.125.251.66

128.125.253.146

128.125.254.1

The Journey of a packet (n)The Journey of a packet (n) 128.125.253.146 128.125.253.146

ApplicatiApplicationon

““I want to receive something on port 5I want to receive something on port 5001”001”

UDPUDP Listening to the port 5001Listening to the port 5001

IPIP

MACMAC

PhysicPhysic



UDPUDP Listening to the Port 5001Listening to the Port 5001

IPIP

MACMAC

PhysicPhysic Get a packet from ethernetGet a packet from ethernetfor yy:yy:yy:yy:yy:yyfor yy:yy:yy:yy:yy:yy



UDPUDP Listening to the Port 5001Listening to the Port 5001

IPIP

MACMAC ““Yes, I am yy:yy:yy:yy:yy:yy”Yes, I am yy:yy:yy:yy:yy:yy”Pass the packet to IPPass the packet to IP

PhysicPhysic Get a packet From ethernet forGet a packet From ethernet foryy:yy:yy:yy:yy:yyyy:yy:yy:yy:yy:yy



UDPUDP Listening to port 5001Listening to port 5001

IPIP From 131.215.44.214 to From 131.215.44.214 to 128.125.253.146:5001128.125.253.146:5001

““Yes, I am 128.125.253.146. ”Yes, I am 128.125.253.146. ”

““Is there any program listening to Is there any program listening to this port?”this port?”

““Yes. One UDP is waiting. Pass it to Yes. One UDP is waiting. Pass it to UDP”UDP”


PhysicPhysic Get a packet From ethernet forGet a packet From ethernet foryy:yy:yy:yy:yy:yyyy:yy:yy:yy:yy:yy



Receive message from Receive message from 131.215.44.214131.215.44.214

UDPUDP Pass to ApplicationPass to Application

IPIP From 131.215.44.214 to From 131.215.44.214 to 128.125.253.146128.125.253.146

““Yes, I am 128.125.253.146. ”Yes, I am 128.125.253.146. ”

““Is there any program waiting for it?”Is there any program waiting for it?”

““Yes. One application is waiting. Pass Yes. One application is waiting. Pass it to UDP”it to UDP”


PhysicPhysic Get a packet From EthernetGet a packet From EthernetFor yy:yy:yy:yy:yy:yyFor yy:yy:yy:yy:yy:yy

OverviewOverview

DirectLink

NetCardDriver

TCP 1

I P

TCP 2 UDP 1 UDP 2

NetCardDriver

TCP 1

I P

UDP 1

Directlink

NetCardDriver

NetCardDriver

TCP 1

I P

TCP 2 UDP 1 UDP 2

Necessary Information Necessary Information (1)(1)

Where shall I pass the packet, for a given Where shall I pass the packet, for a given destination IP address? – Routing Tabledestination IP address? – Routing Table

Exmaple:Exmaple:[weixl@orchestra:~]> route[weixl@orchestra:~]> route

DestinatiDestinationon

GatewayGateway Gen-maskGen-mask FlaFlagsgs

InterfaInterfacece

131.215.131.215.44.044.0

** 255.255.2255.255.255.055.0

UU Eth0Eth0

127.0.0.0 127.0.0.0 ** 255.0.0.0255.0.0.0 UU lolo

default default 131.215.44131.215.44.254.254

0.0.0.00.0.0.0 UFUF Eth0Eth0

Necessary Information Necessary Information (2)(2)

Where shall I pass the packet, for a given Where shall I pass the packet, for a given destination IP address? -- Arpdestination IP address? -- Arp

Exmaple:Exmaple:[weixl@orchestra:~]> arp -a[weixl@orchestra:~]> arp -a131.215.44.227 at 00:06:5B:DE:C5:72 on eth0131.215.44.227 at 00:06:5B:DE:C5:72 on eth0131.215.44.142 at 00:60:B0:7C:E8:02 on eth0131.215.44.142 at 00:60:B0:7C:E8:02 on eth0131.215.44.113 at 00:A0:C9:5A:26:6D on eth0131.215.44.113 at 00:A0:C9:5A:26:6D on eth0131.215.44.80 at 00:E0:81:02:7F:7B on eth0131.215.44.80 at 00:E0:81:02:7F:7B on eth0131.215.44.254 at 00:00:0C:07:AC:01 on eth0131.215.44.254 at 00:00:0C:07:AC:01 on eth0131.215.44.253 at 00:90:6D:E7:D4:00 on eth0131.215.44.253 at 00:90:6D:E7:D4:00 on eth0131.215.44.12 at 00:20:78:1B:13:2C on eth0131.215.44.12 at 00:20:78:1B:13:2C on eth0131.215.44.14 at 00:A0:C9:06:2F:2A on eth0131.215.44.14 at 00:A0:C9:06:2F:2A on eth0

More Information More Information (Bonus)(Bonus)

Get your phone book (Domain Name ServicGet your phone book (Domain Name Service).e).

Example:Example:[weixl@orchestra:~]> ping login.cs.caltech.e[weixl@orchestra:~]> ping login.cs.caltech.e

duduPING orchestra.cs.caltech.edu (131.215.44.2PING orchestra.cs.caltech.edu (131.215.44.2

0) from 131.215.44.20 : 56(84) bytes of data.0) from 131.215.44.20 : 56(84) bytes of data.[weixl@orchestra:~]> freebsd-login.cs.caltec[weixl@orchestra:~]> freebsd-login.cs.caltec

h.edu (131.215.44.14)h.edu (131.215.44.14) API:API:gethostbyname()gethostbyname()

How does DNS work?How does DNS work?

www.mit.eduwww.mit.edu??

18.181.0.3118.181.0.31

131.215.44.214

www.mit.edu?

131.215.44.113

131.215.44.227

HigherDNS

Server

ConnectionConnection

Streamless ConnectionStreamless ConnectionApplicationApplication Socket_send/receiveSocket_send/receive

DNSDNSUDPUDP UDP send/receiveUDP send/receive

IPIP Routing (IP / ARP)Routing (IP / ARP)

MACMAC Ethernet or other Ethernet or other LANLAN

PhysicPhysic Electronic/Optical Electronic/Optical signalssignals

Stream ConnectionStream Connection

ApplicationApplication Socket_send/receiveSocket_send/receiveDNSDNS

TCPTCP How to How to establish/maintain a establish/maintain a

connection?connection?

IPIP Routing (IP / ARP)Routing (IP / ARP)

MACMAC Ethernet/Token RingEthernet/Token Ring or other direct linksor other direct links

PhysicPhysic Electronic/Optical Electronic/Optical signalssignals


An Example: At: 1-626-395-3555 An Example: At: 1-626-395-3555 Call: DMVCall: DMV

Prerequisite: Prerequisite: You know the number of DMV (1-You know the number of DMV (1-

800-777-0133)800-777-0133) The service is now open at DMV.The service is now open at DMV. There is a link between the two There is a link between the two

phones.phones.


Steps at your site:Steps at your site:• Establish the phoneEstablish the phone• Dial the numberDial the number• Select the serviceSelect the service• TalkTalk• Hang upHang up

Steps at DMV:Steps at DMV:• Establish the phone Establish the phone • Establish the service on Establish the service on

phonephone• Accept your requestAccept your request• TalkTalk• Hang UpHang Up

An Example: At: 1-626-395-3555 Call: DMVAn Example: At: 1-626-395-3555 Call: DMV


Steps at DMV:Steps at DMV:• Establish the phoneEstablish the phone• Establish the service on Establish the service on

phonephone• Accept your requestAccept your request• Talk to youTalk to you• Hang UpHang Up

Steps at your site:Steps at your site:• Establish the phoneEstablish the phone• Dial the numberDial the number• Select the serviceSelect the service• Talk to the Talk to the

representativerepresentative• Hang upHang up

Stream ConnectionStream ConnectionSteps at Steps at client’sclient’s site: site:• Establish the Establish the socketsocket• Dial the numberDial the number• Select the serviceSelect the service• Talk to the Talk to the


Steps at Steps at server’s server’s site:site:• Establish the Establish the socketsocket• Establish the serviceEstablish the service• Accept your requestAccept your request• Talk to youTalk to you• Hang UpHang Up

Steps at DMV:Steps at DMV:• Establish the phoneEstablish the phone• Establish the service on Establish the service on


Steps at your site:Steps at your site:• Establish the phoneEstablish the phone• Dial the numberDial the number• Select the serviceSelect the service• Talk to the Talk to the


Stream ConnectionStream ConnectionSteps at Steps at client’sclient’s site: site:• Establish the Establish the socketsocket• Dial the numberDial the number• Select the serviceSelect the service• Talk to the Talk to the


Steps at Steps at server’s server’s site:site:• Establish the Establish the socketsocket• BindBind socket to port socket to port & &

ListenListen• Accept your requestAccept your request• Talk to youTalk to you• Hang UpHang Up

Steps at Steps at client’sclient’s site: site:• Establish the Establish the socketsocket• Dial the numberDial the number• Select the serviceSelect the service• Talk to the Talk to the


Steps at Steps at server’s server’s site:site:• Establish the Establish the socketsocket• Establish the service on Establish the service on


Stream ConnectionStream ConnectionSteps at Steps at client’sclient’s site: site:• Establish the Establish the socketsocket• connectconnect the address ( the address ( IPIP

+ + port port ))• Talk to the Talk to the


Steps at Steps at server’s server’s site:site:• Establish the Establish the socketsocket• Bind socket to a Bind socket to a port & port &


Steps at Steps at client’sclient’s site: site:• Establish the Establish the socketsocket• Dial the numberDial the number• Select the serviceSelect the service• Talk to the Talk to the





+ + port port ))• TalkTalk• Hang upHang up


ListenListen• AcceptAccept the request from the request from

clientclient• Talk to youTalk to you• Hang UpHang Up

Steps at Steps at client’sclient’s site: site:• Establish the Establish the socketsocket• connectconnect the address ( the address ( IPIP

+ + port port ))• Talk to the Talk to the





+ + port port ))• Send/Receive DataSend/Receive Data• Hang upHang up



clientclient• Send/Receive DataSend/Receive Data• Hang UpHang Up


+ + port port ))• TalkTalk• Hang upHang up



clientclient• Talk to youTalk to you• Hang UpHang Up

InsightInsight (from

LinuxFo (from

LinuxForum

)rum

)

CS 145A Lab 1CS 145A Lab 1ConnectionConnection

Netlab.caltech.edu/courseNetlab.caltech.edu/course

How to establish a How to establish a connection?connection?

UDPUDPSteps at Steps at client’sclient’s site: site:• Establish the Establish the socketsocket• Send Data to Send Data to the the

address ( address ( IPIP

+ + port port ))• Close the socketClose the socket

Steps at Steps at server’s server’s site:site:• Establish the Establish the socketsocket• Bind socket to a Bind socket to a portport• Receive DataReceive Data• Close the socketClose the socket

How to establish a How to establish a connection?connection?

TCPTCPSteps at Steps at client’sclient’s site: site:• Establish the socketEstablish the socket• connect the address connect the address

( IP( IP

+ port )+ port )• Send/Receive DataSend/Receive Data• Close the socketClose the socket

Steps at Steps at server’s server’s site:site:• Establish the socketEstablish the socket• Bind socket to a port & Bind socket to a port &

ListenListen• Accept the request from Accept the request from

client and client and create a new create a new socket for socket for communicationcommunication

• Send/Receive Data Send/Receive Data on on the new socketthe new socket

• Close the socketClose the socket

Tasks for Lab 1Tasks for Lab 1

Be familiar with the basic commands tBe familiar with the basic commands that we talked about in class (see those hat we talked about in class (see those examples in the lecture).examples in the lecture).

Write a program (“server”) that can Write a program (“server”) that can act as a Serveract as a Server

Write a program (“udp client”) that cWrite a program (“udp client”) that can send UDP packetsan send UDP packets

Write a program (“tcp client”) that cWrite a program (“tcp client”) that can send TCP packetsan send TCP packets

ServerServer accept TCP connections in one portaccept TCP connections in one port The server should “talk” with the clients. The server should “talk” with the clients.

That is, the server return the same That is, the server return the same contents as the client sends to it. If the contents as the client sends to it. If the client does not send anything in 10 client does not send anything in 10 seconds, the server should actively seconds, the server should actively disconnect the connection. disconnect the connection.

The server is able to “talk” with 5 The server is able to “talk” with 5 different clients at the same time. The different clients at the same time. The server should not keep more than 5 server should not keep more than 5 clients at the same time.clients at the same time.

Server Server

accept UDP packets in one port (may accept UDP packets in one port (may be different from the TCP) be different from the TCP)

The server should talk to the clients.The server should talk to the clients.

The input format:The input format:Server <port 1> <port2>Server <port 1> <port2>(port 1 is for TCP, port2 is for UDP)(port 1 is for TCP, port2 is for UDP)

Tcp clientTcp client send a message to the server, wait for ssend a message to the server, wait for s

everal seconds, then disconnect.everal seconds, then disconnect.Input format:Input format:tcpclient <host> <port> <message> <timtcpclient <host> <port> <message> <tim

e>e><time> is a number indicating the <time> is a number indicating the

seconds the client should wait before dseconds the client should wait before disconnection.isconnection.

Udp clientUdp client send a message to the serversend a message to the server

Input format:Input format:udpclient <host> <port> <message>udpclient <host> <port> <message>

TipsTips For the unknown commands, use For the unknown commands, use

“man”/ “info”/Richard Stevens’ book“man”/ “info”/Richard Stevens’ book Testing: you can use “telnet” to test Testing: you can use “telnet” to test

the server, use the server to test the the server, use the server to test the clients. clients.

How to implement the “disconnection How to implement the “disconnection after 10-sec?”after 10-sec?”

1.1. Child-processChild-process2.2. ““select”select”3.3. ……

Submission (due Submission (due Oct Oct 1818thth))

Task 1: route.txt arp.txt ifconfig.txt traceroute.txtTask 1: route.txt arp.txt ifconfig.txt traceroute.txtTask 2: server.c; server.txtTask 2: server.c; server.txtTask 3: udpclient.c; udpclient.txtTask 3: udpclient.c; udpclient.txtTask 4: tcpclient.c; tcpclient.txtTask 4: tcpclient.c; tcpclient.txtMailto: Mailto: [email protected]@cs.caltech.edu (Do NOT send to (Do NOT send to [email protected]@cs.caltech.edu ) )Documents:Documents: How to use the program: compile, run… How to use the program: compile, run… Your design, your testing, the problems you mYour design, your testing, the problems you m

etet Any other commentsAny other comments

GradingGrading

Correctness (70%) Correctness (70%) Documentation and comments (20%)Documentation and comments (20%) Program style (10%)Program style (10%)

TA HoursTA Hours

Tue: 20:00 ~22:00 JRG 154 / 170Tue: 20:00 ~22:00 JRG 154 / 170 Thu: 20:00 ~22:00 JRG 154 / 170Thu: 20:00 ~22:00 JRG 154 / 170

cs 145a implementation issues

Documents

packet n

idsthe journey

given destination ip

sbintraceroute c

number of dmv

requesttalkhang upan

ipconfig allphysical

overviewnecessary information