Common Network Ports

Question 1

What is FTP?

Answer 1

File Transfer Protocol, a protocol that transfers files from one device to another.

Question 2

What port numbers does FTP use?

Answer 2

FTP uses two port numbers, once is TCP port 20 (for data transfers) and TCP port 21 (for data transfer control)

Question 3

What is SSH?

Answer 3

Secure Shell, a way to connect a remote device through a terminal or command line.

Question 4

What port number does SSH use?

Answer 4

TCP port 22

Question 5

What is Telnet?

Answer 5

Telecommunications Network Protocol, another way to remotely connect to a device. However unlike SSH it is not secure.

Question 6

What port does Telnet use?

Answer 6

TCP port 23

Question 7

What is SMTP?

Answer 7

Simple Mail Transfer Protocol. The protocol that is responsible for sending mail.

Question 8

What port does SMTP use?

Answer 8

TCP port 25

Question 9

What is DNS?

Answer 9

Domain Name System, translates hostnames to IP addresses

Question 10

What port does DNS use?

Answer 10

UDP port 53

Question 11

What is DHCP?

Answer 11

Dynamic Host Configuration Protocol. A protocol that automatically assigns IP addresses. It is automated IP configuration, subnet mask etc.

Question 12

What port does DHCP use?

Answer 12

UDP port 67 and UDP 68

Question 13

How does a DHCP server work?

Answer 13

The server has a large pool of IP addresses to choose from. The IPs are assigned in real time. It uses a leasing system and after use the IP is returned to the pool for others to use.

Question 14

What port does HTTP use?

Answer 14

TCP port 80

Question 15

What port does HTTPS use?

Answer 15

TCP port 443

Question 16

What is POP3?

Answer 16

Post Office Protocol version 3. A protocol designed to receive email messages to an email client. Not for multiple clients.

Question 17

What port does POP3 use?

Answer 17

TCP port 110

Question 18

What is IMAP4?

Answer 18

Internet Message Access Protocol. An email receiving protocol that is able to synchronize across multiple devices.

Question 19

What port does IMAP4 use?

Answer 19

TCP port 143

Question 20

What is SMB?

Answer 20

Server Message Block. A communication protocol that transfer files and information between devices, commonly used by Wndows.

Question 21

What is NetBios?

Answer 21

Network Basic Input/Output. a protocol used by older Windows Machines, used by SMB.

Question 22

What protocol does NetBios use?

Answer 22

UDP port 137 as a name service function, and TCP port 139 to set up a session and transfer data between devices.

Question 23

On modern machines with a direct SDB connection, what ports are used?

Answer 23

TCP port 445

Question 24

What is SNMP?

Answer 24

Simple Network Management Protocol. It allows a network management device to query these infrastructure devices for performance details and receive those metrics in return.

Question 25

What port does SNMP use?

Answer 25

UDP port 161 for the queries. For the alerts or “traps” when notifying of exceeded metrics, it uses UDP port 162.

Question 26

How many versions of SNMP exist?

Answer 26

V1 (unecrypted), V2 (allowed for bulk transfers but still unencrypted), V3 (the version with additional security)

Question 27

What is LDAP?

Answer 27

Lightweight Directory Access Protocol, an example of LDAP is microsofts Active Directory

Question 28

What port does LDAP use?

Answer 28

TCP port 389

Question 29

What is RDP?

Answer 29

Remote Desktop Protocol, a way to share remote desktop. The standard protocol used for windows sharing. RDP can be used to run an entire system or just take over a single application.