Podcast
Questions and Answers
Which of the following scenarios would MOST likely result in a computer being assigned a dynamic port number?
Which of the following scenarios would MOST likely result in a computer being assigned a dynamic port number?
- A user opens their email client to check for new messages. (correct)
- An administrator manually configures a static IP address for a network printer.
- A system process requires a persistent, well-known communication channel.
- A web server is configured to listen for incoming HTTP requests.
A network administrator is troubleshooting a connection issue to a remote server. They successfully ping the server's IP address, but cannot establish a connection to the application running on port 8080. What is the MOST probable cause of this issue?
A network administrator is troubleshooting a connection issue to a remote server. They successfully ping the server's IP address, but cannot establish a connection to the application running on port 8080. What is the MOST probable cause of this issue?
- There is an issue with DNS resolution, preventing the client from resolving the server's hostname to its IP address correctly.
- The server's firewall is blocking ICMP traffic, but allowing traffic on port 8080.
- The client's operating system has not assigned a dynamic port number to the connection attempt.
- The application on the server is not listening on port 8080, or a firewall is blocking traffic to that port. (correct)
A security analyst observes multiple connections to a server on ports 49152 and above. What type of activity might this indicate?
A security analyst observes multiple connections to a server on ports 49152 and above. What type of activity might this indicate?
- A misconfigured DNS server directing traffic to incorrect destinations.
- Legitimate client applications establishing connections to server applications. (correct)
- An attempt to exploit well-known vulnerabilities in common network services.
- A server hosting legacy applications that rely on older protocols like Telnet and FTP.
What is the fundamental difference between TCP and ICMP in the context of network communication?
What is the fundamental difference between TCP and ICMP in the context of network communication?
If the TCP header's port field is 16 bits long, why are there only 65,536 (2^16) available port numbers instead of more?
If the TCP header's port field is 16 bits long, why are there only 65,536 (2^16) available port numbers instead of more?
A system administrator needs to identify the specific process using port 49155. Which netstat command option would give them the necessary information?
A system administrator needs to identify the specific process using port 49155. Which netstat command option would give them the necessary information?
An organization is implementing a new web application that requires secure communication. Which port should be configured for HTTPS, and why is this important?
An organization is implementing a new web application that requires secure communication. Which port should be configured for HTTPS, and why is this important?
How does the concept of a 'socket' facilitate network communication between two applications?
How does the concept of a 'socket' facilitate network communication between two applications?
Why is it important for operating systems to assign dynamic port numbers randomly within the range of 49152-65535?
Why is it important for operating systems to assign dynamic port numbers randomly within the range of 49152-65535?
Which of the following services is MOST likely to be listening on a port within the Well Known port range (0-1023)?
Which of the following services is MOST likely to be listening on a port within the Well Known port range (0-1023)?
Flashcards
IP Address
IP Address
A unique numerical identifier assigned to a device connected to a network, either manually (static) or automatically (DHCP).
PING Command
PING Command
Command used to test network connectivity. It sends a request to another computer and waits for a reply.
Port Number
Port Number
A numerical identifier assigned to applications/programs by the TCP/IP service, managed by the Internet Assigned Numbers Authority (IANA).
Port 80
Port 80
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Port 443
Port 443
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Socket
Socket
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Well-Known Ports
Well-Known Ports
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Registered Ports
Registered Ports
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Dynamic Ports
Dynamic Ports
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Netstat
Netstat
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Study Notes
- A computer receives an IP address when it connects to a network.
- IP addresses can be assigned manually (static) or automatically via DHCP.
- Connectivity to a computer can be tested using the PING command.
- An active path to another computer exists when a reply is received from a ping.
- Ping is one command that is part of the Internet Control Messaging Protocol (ICMP).
- IP addressing is examined in the INFO1220 Networking course.
- Programs running on a computer are assigned a port number via the TCP/IP service.
- Port numbers are assigned to programs by the Internet Assigned Numbers Authority (IANA).
- Port 80 is the HTTP protocol, used by web servers.
- Port 443 is the HTTPS protocol, used for encrypted packets to web servers.
- Port 23 is the Telnet protocol, for terminal console connections.
- Port 21 is the File Transfer Protocol (FTP).
- The TCP/IP service will be studied in-depth in this and other courses in the CYB program.
- A computer with a single IP address may run several applications, each with different TCP port numbers, allowing multitasking.
- Connections to services on other computers involve sending packets to the computer's IP address and the program's port number.
- To connect to a web server, an IP packet is sent to port 80.
- An IP address and port combination is a socket, e.g., 192.168.1.16:80.
- The command http:\192.168.1.16 assumes destination port 80 because it is assigned to the HTTP protocol.
- There are 65536 available port numbers, each port field in a TCP header is 16 bits long.
- Port numbers are arranged into three ranges.
- Ports 0-1023 are Well Known ports, used by original TCP/IP applications like FTP.
- Ports 1024-49151 are Registered Ports, assigned to newer applications.
- Ports 49152-65535 are Dynamic ports assigned by the operating system when a program such as Chrome is started.
- The operating system assigns port numbers to applications without well-known port numbers
- Port 80 is reserved for web servers.
- When a browser opens, a port number in the range 49152-65535 (the ephemeral range) is assigned.
- If a browser opens a second time, a different port number is assigned.
- A computer may have several TCP/IP connections established at the same time on a single IP address.
- The netstat command views current connections, it also has options for listing connection information details.
- Windows has well-known services listening in the upper range of port numbers, by default.
- Examples include wininit.exe: 49152, event log service: 49153, schedule service: 49154, services.exe: 49155, lsass.exe: 49156.
- The netstat command with the -abn option displays the service running the listening port.
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