Common Ports

Question 1

FTP

Answer 1

File Transfer Protocol

20 / 21

Question 2

SSH

SCP

Answer 2

Secure Shell

Secure Copy

22

Question 3

Telnet

Answer 3

23
TCP

Question 4

SMTP

Answer 4

Simple Mail Transfer Protocol

25

TCP

Question 5

TACACS

Answer 5

Terminal Access Controller Access-Control System

49

TCP & UDP

Question 6

DNS

Answer 6

Domain Name Service

53

TCP & UDP

Question 7

DHCP

Answer 7

Dynamic Host Configuration Protocol

67 / 68
UDP

Question 8

TFTP

Answer 8

Trivial File Transfer Protocol

69 UDP

Question 9

HTTP
Hper Text Transfer Protocol

Answer 9

80 TCP

Question 10

Kerberos

Answer 10

88 TCP

Question 11

POP3
Post Office Protocol V

Answer 11

110 TCP

Question 12

NNTP
Network News Transfer Protocol

Answer 12

119 TCP

Question 13

NTP
Network Time Protocol

Answer 13

123 UDP

Question 14

NetBIOS
Network Basic Input/Output System

Answer 14

135 TCP
137 TCP & UDP
139 TCP

Question 15

IMAP4
Internet Message Access Protocol

Answer 15

143 TCP & UDP

Question 16

SNMP
Simple Network Management Protocol

Answer 16

161
162
TCP & UDP

Question 17

LDAP
Lightweight Directory Access Protocol

Answer 17

389 TCP & UDP

Question 18

HTTPS
HTTP with secure socket layer (SSL/TLS)

Answer 18

443 TCP & UDP

Question 19

CIFS / SMB
Common Internet File System /
Server Message Block

Answer 19

445 TCP

Question 20

IKE
Internet Key Exchange
*Used with IPSec

Answer 20

500 UDP

Question 21

LDAPS
Lightweight Directory Access Protocol over SSL / TLS

Answer 21

636 TCP & UDP

Question 22

FTPS
File Transfer Protocol Secure
* Over SSL/TLS

Answer 22

989
990
TCP & UDP

Question 23

L2TP
Layer 2 Tunneling Protocol

Answer 23

1701 UDP

Question 24

PPTP
Point to Point Tunneling Protocol

Answer 24

1723 TCP & UDP

Question 25

RADIUS
Remote Authentication Dial In User Service

Answer 25

1812
1813
TCP & UDP

Question 26

RDP
Remote Desktop Protocol

Answer 26

3389 TCP

Question 27

Netstat -a

Answer 27

Command to see all open ports