Chapter 9: TCP/IP Applications

Question 1

Describe the TCP three-way handshake.

Answer 1

client -> synchronize -> server

client acknowledge -> server

Question 2

Describe how a TCP session closes.

Answer 2

client acknowledge>server
client ->finished acknowledge -> server
client<- server

Question 3

What ports does DHCP work on?

Answer 3

port 67 is used to send data to server

port 68 servers use to send data to DHCP clients

Question 4

What port does NTP/SNTP use?

Answer 4

port 123

Question 5

Describe TFTP.

Answer 5

uses UDP, no data proection

-uses port 69

Question 6

Describe ICMP.

Answer 6

Layer 3 to deliver connectionless packets

Question 7

Describe IGMP

Answer 7

Internet Group management protocol
used for multicasting
-particular multicast assigned to a 224.0.0.0/4
-hosts want to receive tell upstream router that they do.

Question 8

What is a port number?

Answer 8

• 16 bit value between 0 and 65535
• 0 to 1023 are well known port numbers and reserves
• 1024-49151: registered ports
• 49,152 -65635: dynamic or private port numbers

Question 9

What is a socket/endpoint?

Answer 9

session that is stored in RAM

-netstat -n shows you the endpoint

Question 10

what command shows all listening ports?

Answer 10

netstat -an

Question 11

What command shows the process id

Answer 11

netstat -ano

Question 12

what tels you the name of the running program

Answer 12

netstat -G

Question 13

What port does HTTPS use?

Answer 13

443

Question 14

What is TLS

Answer 14

Transport Layer Security

Question 15

What port does telnet use?

Answer 15

23, TCP

Question 16

Describe rlogin.

Answer 16

• can configure to login automatically interactively
• only connects to unix hosts
• port 513

Question 17

describe remote shell(RSH).

Answer 17

single commands to remote server

• easily integrated into a script
• port 514

Question 18

describe Remote Copy Protocol(RCP)

Answer 18

• copy files to and from remote server
• can be used in scripts
• port 514

Question 19

Describe SMTP.

Answer 19

• used to send email
• uses port 25
• used by clients to send messages

Question 20

Describe POP3

Answer 20

• receive email from SMTP servers

- port 110

Question 21

Describe IMAP4.

Answer 21

• Retrieves email from email server
• port 143
• can search through messages
• folders.

Question 22

Describe sendmail.

Answer 22

-used on Linux and UNIX and only uses SMTP

Question 23

Describe Microsoft Exchange Server.

Answer 23

• only runs on windows

- SMTP and POP3 in one package.

Question 24

Describe FTP.

Answer 24

uses ports 21 and 20

• not secure because data transfers aren’t encrypted
• passive FTP only uses port 21

Question 25

Describe active FTP

Answer 25

-doesn’t work if you use NAT

Question 26

Describe passive FTP

Answer 26

• server doesn’t use port 20.
• client sends request on port 21
• server sends back random port # tells client which port its listening to for data requests.
• client initiates all conversations, NAT router knows where to send the packet.
• client needs to expect this incoming data.

Question 27

What port does HTTP use?

Answer 27

-TCP, port 80

Question 28

What port does HTTPS use?

Answer 28

TCP, port 443,

Question 29

What port does telnet use?

Answer 29

TCP port 23

Question 30

What port does SSH use?

Answer 30

TCP, port 22

Question 31

What port does SMTP use?

Answer 31

TCP port 25

Question 32

What port does POP3 use?

Answer 32

TCP port 110

Question 33

What port does IMAP4 use?

Answer 33

TCP port 143

Question 34

What port does FTP use?

Answer 34

TCP port 20/21

Question 35

What port does TFTP use?

Answer 35

UDP port 69