CS70 Networking Theory and Essentials

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Homework -
read - link entitled "Playing client with telnet and netcat" and links it contains
do - related assignment at link entitled "Assgt 9 false telnet". due 5/10 on sputnik
read - textbook chapters 35,36 about web service, and 31 about name service. (5/4)

Ports - what normally uses port 25? what normally uses port 110? (5/4)

Slides posted - from last week's discussion, at links entitled "netstat" and "nmap." (5/3)

Test - April 26. Please bring a scantron. (4/18)

TCP Ports you should know
Q: where do the "well-known port" numbers come from?
A: IANA (Internet Assigned Numbers Authority)

Q: what are the well-known port assignments?
A: the list is long (cf., /etc/services on any linux box)

Q: which ones should we know for this class?
A: 21, 23, 25, 53, 80, 110, 137-39 (look up what service each belongs to, above)
(4/18)

Various services and the server programs and protocols they use.

Service	Server	Linux executable	Protocol used
name	BIND	/usr/sbin/named	dns
web	APACHE	/usr/sbin/httpd	http
MS sharing	SAMBA	/usr/sbin/smbd	smb
address	DHCP	/usr/sbin/dhcpd	dhcp
socket demo	CHOMPER	/opt/socketdemo/byteme	none
letter upgrade	letter upgrade	server3	none, really

(4/18)

Student internship - at Sun Microsystems El Segundo. (4/16)

Spring break April 12 - no class that day. (3/28)

Homework -
do - assignment 7.5. due 3/29
do - assignment 7.7. I will talk a little further about it 3/29. due 4/5

Homework -
anticipate - in-class internetworking lab/demo we will collectively perform
- read chapters 17 (internetworking) and 20 (datagram forwarding)
- read page at link entitled "Masks, routing, subnets" at left
- print out worksheet at link entitled "internetworking" at right. Bring to class.
read - the other chapters dealing with the topics we've been discussing. They haven't been explicitly assigned on an individual basis so far, only in the reading list below. You'll be responsible for them come test time soon. They are all the chapters up through 16. Read only those portions indicated in the reading list below, as your schedule allows, by test time. (3/18)

Slides we viewed recently were the ones at the link entitled "Interfaces and routes" and portions of "IP network addresses" in the lefthand column. We also looked at the Forte Systems presentation featuring Sally and Harry (golden rules: "if local ARP it, if remote ARP the gateway instead"), found at the link entitled "IP packet delivery" at left. (3/18)

Routing
Three kinds of routes can appear in a routing table: host route for a specified individual machine, network route for a specified grouping of them, default route as catch-all for everything (unspecified) else. Here are the four key linux command formulations by which you add such routes to a routing table. Though there are 3 kinds of routes, note that 4 command formulations appear. We mentioned the concept of gateways (machines other than the destination, to which you would send the destination's packets for forwarding). That accounts for there being 2 network route formulations below.

Add route to a machine (host route):
route add –host 192.168.4.2 eth0
Add route to a group of machines (network route - local)
route add –net 192.168.4.0 netmask 255.255.255.0 eth0
Add route to a group of machines (network route - gatewayed)
route add –net 192.168.5.0 netmask 255.255.255.0 gw 192.168.4.1
Add route to “any and all” (default route)
route add default gw 192.168.4.1

You will employ these commands in the future. Study them intently and try to grasp the semantic meaning they embody. (3/18)

Network size for common netmasks:

Netmask:	# of zero bits:	Implied network size:
255.255.255.128	7	128 (126)
255.255.255.192	6	64 (62)
255.255.255.224	5	32 (31)
255.255.255.240	4	16 (14)
255.255.255.248	3	8 (6)
255.255.255.252	2	4 (2)

Request - please don't change the root account passwords on the lab computers, as 3 different classes use them. (3/2)

Accounts on sputnik.smc.edu were created today - see "Remote Unix system" paragraph below. (2/24)

Slides we view initially are the ones at the links entitled "Concepts, " "Design," "Media," and "NICs" in the lower section of the lefthand column headed "Slide presentations". Source code for the textbook's Chapter 3 demo programs "echoserver.c" and "echoclient.c" are at the links of the same name (as well as in Chapter 3). (2/15)

Homework -
read - textbook Chapters 1-3. I will demonstrate the client and server programs featured in chapter 3.
print out - the document at the link entitled "TCP/IP Pocket Reference Guide"
print out - the document at the link entitled "TCP/IP - Intro to the IP Protocols"
the links are all in the column at left; bring both printouts to the next class. (2/15)

Remote Unix system
Your username - your last name as it appears on my class list, all lowercase.
Your password - is 5 digits extracted from your phone number. If your phone number is 123-456-9876, then your password will be 56987 (final 2 digits from the 3-digit exchange, plus first 3 digits of the 4-digit number).
The target computer - is sputnik.smc.edu
Log in method - the assignment asks you to "log in." Translation: use telnet as discussed in class and described in the "Remote Unix access with Telnet" link at left. (2/15)

Reading	portions of textbook for you to read
Part I	Introductory
Chapters 1-3		all
Part II	Data Transmission
Chapter 4	media	all
Chapter 5	signaling	5.1-5.3
Chapter 6	modulation/multiplexing	6.1-6.5
Part III	Packet Transmission
Chapter 7	packets	7.1-7.4
Chapter 8	topologies	8.1-8.9
Chapter 9	hardware/ethernet addressing	9.1-9.5, 9.8-9.10, 9.12
Chapter 10	wiring	all
Chapter 12	dsl/cable	12.13, 12.15-12.18
Chapter 13	switching/routing	13.1-13.12
Chapter 16	protocol layering	16.1-16.9
Part IV	Internetworking
Chapter 17	internetworking concepts	all
Chapter 18	ip	all
Chapter 19	arp	all except 19.6
Chapter 20	ip forwarding/routing	all
Chapter 23	icmp	all
Chapter 24	udp	all
Chapter 25	tcp	all
Chapter 26	network address translation	all
Part V	Network Applications
Chapter 28	client-server model	all
Chapter 29	socket interface	29.1-29.9
Chapter 31	name service (dns)	31.1, 31.6-31.11
Chapter 35	web service (http)	35.12-35.14
Chapter 36	dynamic web (cgi, php...)	36.4-36.7
Chapter 40	network security	40,10-40.12
Chapter 41	address service (dhcp)	all

TCP/IP and tcpdump Pocket Reference Guide - from SANS Institute. Please print it out 2-sided, fold it in 3 panels triptych style, and carry it with your materials for this class. The link to it is at left; it is an Adobe Acrobat .pdf file. (2/15)

"Live linux" CDs - here's a list of various self-contained bootable linux CDs. They typically convert memory into a RAM-disk, populate it with foundation files for the operating system, and proceed to boot linux. They do not molest your hard disk. The best known is probably knoppix (remarkable). FYI. (2/15)

Wireshark - is an excellent free packet capture utility. What is a packet, and why caputre it? We'll talk about that later. I will ask you to install and use Wireshark later in the semester, assuming you have a linux or windows computer available on which to do so. Please visit http://www.wireshark.org/. (2/15)