1.5 Explain common ports and protocols, their application, and encrypted alternatives.

Question 1

File Transfer Protocol (FTP)

Answer 1

20/21
Provides insecure file transfers

Question 2

Secure Shell (SSH)

Answer 2

22
provides secure remote control of another machine using a text-based environment

Question 3

Secure File Transfer Protocol (SFTP)

Answer 3

22
provides secure file transfers

Question 4

Telnet

Answer 4

23
provides insecure remote control of another machine using a text-based environment

Question 5

Simple Mail Transfer Protocol (SMTP)

Answer 5

25
provides the ability to send emails over the network

Question 6

Domain Name System (DNS)

Answer 6

53
converts domain names to IP addresses, and IP addresses to domain names

Question 7

Dynamic Host Configuration Protocol (DHCP)

Answer 7

67 & 68
automatically provides network parameters to your clients, such as their assigned IP address, subnet mask, default gateway, and the DNS server they should use

Question 8

Trivial File Transfer Protocol (TFTP)

Answer 8

69
used as a lightweight file transfer method for sending configuration files or network booting of an operating system

Question 9

Hypertext Transfer Protocol (HTTP)

Answer 9

80
used for insecure web browsing

Question 10

Post Office Protocol v3 (POP3)

Answer 10

110
used for receiving incoming emails

Question 11

Network Time Protocol (NTP)

Answer 11

123
used to keep accurate time for clients on a network

Question 12

Internet Message Access Protocol (IMAP)

Answer 12

143
a newer method of retrieving incoming emails which improves upon the older POP3

Question 13

Simple Network Management Protocol (SNMP)

Answer 13

161 & 162
used to collect data about network devices and monitor their status

Question 14

Lightweight Directory Access Protocol (LDAP)

Answer 14

389
used to provide directory services to your network

Question 15

Hypertext Transfer Protocol Secure (HTTPS) [Secure Sockets Layer (SSL)]

Answer 15

443
used as a secure and encrypted version of web browsing

Question 16

HTTPS [Transport Layer Security (TLS)]

Answer 16

443
used as a secure and encrypted version of web browsing

Question 17

Server Message Block (SMB)

Answer 17

445
used for windows file and printer sharing services

Question 18

Syslog (System Logging Protocol)

Answer 18

514
used to send logging data back to a centralized server

Question 19

SMTP TLS

Answer 19

587
secure and encrypted way to send emails

Question 20

Lightweight Directory Access Protocol (over SSL) (LDAPS)

Answer 20

636
provides secure directory services

Question 21

IMAP over SSL

Answer 21

993
secure and encrypted way to receive emails

Question 22

POP3 over SSL

Answer 22

995
secure and encrypted way to receive emails

Question 23

Microsoft (SQL) Server

Answer 23

1433
used for communication from a client to the database engine

Question 24

SQLnet

Answer 24

1521
used for communication from a client to an Oracle database

Question 25

MySQL

Answer 25

3306
used for communication from a client to the MySQL database engine

Question 26

Remote Desktop Protocol (RDP)

Answer 26

3389
provides graphical remote control of another client/server (it is encrypted/secure)

Question 27

Session Initiation Protocol (SIP)

Answer 27

5060 & 5061
used to initiate VoIP and video calls

Question 28

Corporate hired a penetration testing expert to test their internal security. The final report given to the executives shows that the way the expert circumvented their security was by using port 1521 from a remote location. The expert suggested enabling access control lists on that service. What protocol did the expert use to infiltrate the network?

Syslog

SQLnet

Telnet

MySQL

Answer 28

Oracle’s remote data access protocol SQL*Net uses TCP/1521. Access lists should secure these ports to provide security.

Syslog is an example of a protocol and supporting software that facilitates log collection. It has become a de facto standard for logging events from distributed systems on port 514.

Telnet is both a protocol and a terminal emulation software tool that transmits shell commands and output between a client and the remote host on port 23.

The open-source MySQL platform uses TCP/3306. The MariaDB platform forked from MySQL uses the same port.

Question 29

A network administrator is monitoring network traffic and notices a severe spike on port 993. Which protocol is causing the spike in network traffic?

SMTP

IMAP over SSL

IMAP

POP3 over SSL

Answer 29

A client connects to an IMAP server over port 143 and establishes connection security using a TLS. The default port for IMAPS (IMAP over SSL) is TCP/993.

A client establishes a connection to the POP server on TCP port 110. Using TLS encryption can secure POP. The default TCP port for secure POP (POP3S) is port 995.

A client connects to an IMAP server over TCP port 143. Like POP, IMAP is a mail retrieval protocol, but with mailbox management features lacking in POP.

SMTP is useful only to deliver mail to permanently available hosts. When an SMTP server receives a message, it delivers the message to a mailbox server using port 25.

Question 30

A client is attempting to connect to a network, but is unable to successfully connect. They decide to open Wireshark to see if they can troubleshoot but want to filter based on the DHCP port. What should they filter on?

TCP 67

TCP 80

UDP 123

TCP 139

Answer 30

Information can be viewed from Dynamic Host Configuration Protocol (DHCP) traffic by filtering on TCP 67 and 68. DHCP dynamically assigns IP addresses to network hosts.

Server Message Block (SMB) provides File/Print Sharing Service and operates on TCP 139 and 445. SMB allows a machine to share its files and printers to make them available.

Hypertext Transfer Protocol (HTTP) operates over TCP 80 and enables clients to request resources from a HTTP server.

The Network Time Protocol (NTP) enables the synchronization of time-dependent applications. A server or host that is configured with the incorrect time may not be able to access network services. Authentication, and other security mechanisms will often fail if the time is not synchronized on both communicating devices. Errors are likely to be generic failed or invalid token messages.

Question 31

Which port will a Domain Name Server (DNS) use for record transfers over 512 bytes?

Transmission Control Protocol (TCP) port 23

User Datagram Protocol (UDP) 69

Transmission Control Protocol (TCP) port 53

User Datagram Protocol (UDP) port 53

Answer 31

A Domain Name Server (DNS) server that needs to allow large record transfers over 512 bytes will be configured to allow connections over Transmission Control Protocol (TCP) port 53.

A DNS server is usually configured to listen for queries on User Datagram Protocol (UDP) port 53. Larger transfers (over 512 bytes) require use of TCP port 53.

Telnet uses TCP port 23 by default. Telnet is terminal emulation software to support a remote connection to another computer.

Trivial File Transfer Protocol (TFTP) is a connectionless protocol running over User Datagram Port 69.

Question 32

A router downloads configuration files over User Datagram Protocol (UDP) port 69. The router does not have access to browse the directory or to delete files. Analyze File Transfer Protocols (FTPs) and determine what protocol the router is using.

Active File Transfer Protocol (FTP)

Trivial File Transfer Protocol (TFTP)

File Transfer Protocol over Secure Sockets Layer (SSL)

Secure File Transfer Protocol (SFTP)

Answer 32

The Trivial File Transfer Protocol (TFTP) is a connectionless protocol that runs over User Datagram Port (UDP) port 69. TFTP supports reading and writing files, not directory browsing or file deletion.

Secure FTP (SFTP) runs over Transmission Control Protocol (TCP) port 22. SFTP addresses the privacy and integrity issues of FTP by encrypting the authentication and data transfer.

FTP connects to TCP port 21 on an FTP server and opens a chosen dynamic client port number (N). In active mode, the client sends a PORT command specifying the chosen data connection port number (typically N+1).

FTP over Secure Sockets Layer (SSL) uses either Explicit Transport Layer Security (FTPES) or Implicit Transport Layer Security (FTPS) for secure communication.

Question 33

A new system administrator configures a shared repository for access to files through a web-based interface. What port must the administrator enable on the repository?

21

445

22

80

Answer 33

The Hypertext Transfer Protocol (HTTP) enables clients to request resources from an HTTP server. HTTP uses port 80.

Secure Shell (SSH) is the principal means of obtaining secure remote access to a UNIX or Linux server. SSH uses port 22.

The Server Message Block (SMB) protocol provides File/Print Sharing Service. SMB allows a machine to share its files and printers to make them available. SMB uses port 445.

File Transfer Protocol (FTP) connects to Transmission Control Protocol (TCP) port 21 on an FTP server and opens a chosen dynamic client port number for communications and transfers.