Important Ports - By Name

Question 1

File Transfer Protocol (FTP)

Answer 1

20/21 - TCP - Port 21 is the control port while port 20 is used to transfer files.

Question 2

Secure Shell (SSH)

Answer 2

22 - TCP - Designed to transmit data through a remote connection.

Question 3

SSH File Transfer Protocol

Answer 3

22 - TCP - A completely separate protocol from FTP (it is not compliant with FTP servers) that uses SSH to encrypt file transfers.

Question 4

Simple Mail Transfer Protocol (SMTP)

Answer 4

587 - TCP - Internet mail protocol used to send outgoing mail from email clients to mail servers. old port used was 25.

Question 5

TACACS+

Answer 5

49 - TCP - Cisco proprietary protocol used for authentication, authorization, and accounting (AAA) services.

Question 6

Domain Name System (DNS)

Answer 6

53 - UDP - Used to associate IP addresses with domain names

Question 7

Dynamic Host Configuration Protocol (DHCP)

Answer 7

67/68 - UDP - This network management protocol is used to assign multiple local private IP addresses from one public IPv4 address.

Question 8

Hypertext Transfer Protocol (HTTP)

Answer 8

80 - TCP - Protocol used for websites and most internet traffic.

Question 9

Kerberos

Answer 9

88 - TCP/UDP - Network authentication protocol that allows for communication over a non-secure network. Primarily uses UDP but can use TCP.

Question 10

Post Office Protocol (POP)

Answer 10

110 - TCP - E-mail protocol that allows e-mail clients to communicate with e-mail servers. POP provides only one-way communication.

Question 11

Network Time Protocol

Answer 11

123 - UDP - Low latency protocol used to synchronize timekeeping across a network.

Question 12

Server Message Block (SMB)

Answer 12

445 - UDP - Windows proprietary protocol built on NetBIOS. Allows users to remotely access servers. Originally used port 139.

Question 13

Internet Message Access Protocol (IMAP)

Answer 13

143, 993 - TCP - E-mail protocol used by e-mail clients to communicate with e-mail servers. Provides two way communication unlike POP.

Question 14

Simple Network Management Protocol (SNMP)

Answer 14

161/ 162 - UDP - Protocol used to monitor and manage network devices on IP networks.

Question 15

Lightweight Directory Access Protocol (LDAP)

Answer 15

389 - UDP - Used to manage and communicate with directories.

Question 16

Hypertext Transfer Protocol Secure (HTTPS)

Answer 16

443 - TCP - Secure version of HTTP that used TLS for encryption. Most websites use HTTPS instead of HTTP.

Question 17

Secure Socket Tunneling Protocol (SSTP)

Answer 17

443 - TCP - Microsoft developed SSTP technology to replace the more insecure PPTP or L2TP/IPSec options available in Windows. SSTP uses TLS.

Question 18

Server Message Block (SMB)

Answer 18

445 - TCP - Windows proprietary protocol built on NetBIOS. Allows users to remotely access servers.

Question 19

Internet Protocol Security (IPSec) using ISAKMP

Answer 19

500 - UDP - Internet Protocol security achieved through the use of ISAKMP Internet Security Association and Key Management Protocol.

Question 20

Simple Mail Transfer Protocol Secure (SMTPS)

Answer 20

587 - TCP - The secure version of SMTP. Uses TLS for encryption.

Question 21

Lightweight Directory Access Protocol Secure (LDAPS)

Answer 21

636 - TCP - Secure version of LDAP that uses TLS for encryption.

Question 22

File Transfer Protocol Secure (FTPS)

Answer 22

989/ 990 - TCP - Uses TLS for encryption. It can run on ports 20/21

Question 23

Internet Message Access Protocol Secure (IMAPS)

Answer 23

993 - TCP - Secure version of IMAP that uses TLS for encryption.

Question 24

Post Office Protocol 3 Secure (POP3S)

Answer 24

995 - TCP - Secure version of POP that uses TLS for encryption.

Question 25

Remote Authentication Dial-In User Service (RADIUS)

Answer 25

1812, 1813 - UDP - Used to provide AAA for network services.

Question 26

Remote Desktop Protocol (RDP)

Answer 26

3389 - TCP - This Windows proprietary protocol that enables remote connections to other computers.

Question 27

Diameter

Answer 27

3868 - TCP - Developed as an upgrade to Radius.

Question 28

Secure Real Time Protocol (SRTP)

Answer 28

5004 - UDP - SRTP replaced RTP and is a protocol used to stream audio and video communication using UDP.�

Question 29

Transmission Control Protocol (TCP)

Answer 29

N/A - One of two main protocols of the Internet Protocol (IP) suite used to transmit data over an IP network.� TCP provides error checking to ensure packets are not lost in transit. - Layer 4 (Transport Layer)

Question 30

User Datagram Protocol (UDP)

Answer 30

N/A - The second main protocol in the IP suite that transmits datagrams in a best effort method.� UDP does not include error checking. - Layer 4 (Transport Layer)

Question 31

Point to Point Tunneling Protocol (PPTP)

Answer 31

1723 - Layer 4 (Transport Layer) - TCP - Based on PPP. Deprecated protocol for VPNs.

Question 32

Layer 2 Tunneling Protocol (L2TP)

Answer 32

1701 - layer 2 (Data Link Layer) - UDP - Used to create point to point connections, like VPNs over a UDP connection. Needs IPSec for encryption. Designed as an extension to PPTP.� Operates at the data link layer but encapsulates packets at the session layer.

Question 33

Point to Point Tunneling Protocol (PPTP)

Answer 33

1723 - layer 2 (Data Link Layer) - UDP - Based on PPP. Deprecated protocol for VPNs.