COURSE 3 - Connect and Protect: Networks and Network Security Flashcards
A _______ is a network device that broadcasts information to every device on the network. Think of a hub like a radio tower that broadcasts a signal to any radio tuned to the correct frequency.
hub
A _________ makes connections between specific devices on a network by sending and receiving data between them. A _________ is more intelligent than a hub. It only passes data to the intended destination. This makes _________es more secure than hubs, and enables them to control the flow of traffic and improve network performance.
switch
A ___________ is a network device that connects multiple networks together.
For example, if a computer in one network wants to send information to a tablet on another network, then the information will be transferred as follows: First, the information travels from the computer to the _________. Then, the _________ reads the destination address, and forwards the data to the intended network’s _________. Finally, the receiving router directs that information to the tablet.
router
A ____________ is a device that connects your router to the internet, and brings internet access to the LAN.
For example, if a computer from one network wants to send information to a device on a network in a different geographic location, it would be transferred as follows: The computer would send information to the router, and the router would then transfer the information through the ___________ to the internet. The intended recipient’s ___________ receives the information, and transfers it to the router. Finally, the recipient’s router forwards that information to the destination device.
modem
A _____________ is a basic unit of information that travels from one device to another within a network.
data packet
____________ refers to the amount of data a device receives every second. You can calculate __________ by dividing the quantity of data by the time in seconds. Speed refers to the rate at which data packets are received or downloaded. Security personnel are interested in network bandwidth and speed because if either are irregular, it could be an indication of an attack. Packet sniffing is the practice of capturing and inspecting data packets across the network.
Bandwidth
What is in the header of a data packet?
A data packet is very similar to a physical letter. It contains a header that includes the internet protocol address, the IP address, and the media access control, or MAC, address of the destination device. It also includes a protocol number that tells the receiving device what to do with the information in the packet.
TCP/IP stands for Transmission Control Protocol and Internet Protocol.
TCP/IP is the standard model used for network communication.
______, or ______________, is an internet communication protocol that allows two devices to form a connection and stream data. The protocol includes a set of instructions to organize data, so it can be sent across a network. It also establishes a connection between two devices and makes sure that packets reach their appropriate destination.
TCP - Transmission Control Protocol
__ stands for __________. has a set of standards used for routing and addressing data packets as they travel between devices on a network. Included in the _____________ is the IP address that functions as an address for each private network. You’ll learn more about IP addresses a bit later.
IP Internet Protocol
Within the operating system of a network device, a _____ is a software-based location that organizes the sending and receiving of data between devices on a network. ______(s) divide network traffic into segments based on the service they will perform between two devices. The computers sending and receiving these data segments know how to prioritize and process these segments based on their _____ number.
Port
Some common port numbers are:
port 25, which is used for e-mail
port 443, which is used for secure internet communication
port 20, for large file transfers
The TCP/IP model is a framework that is used to visualize how data is organized and transmitted across the network. The TCP/IP model has four layers. The four layers are:
the network access layer
The network access layer deals with creation of data packets and their transmission across a network. This includes hardware devices connected to physical cables and switches that direct data to its destination.
the internet layer
The internet layer is where IP addresses are attached to data packets to indicate the location of the sender and receiver. The internet layer also focuses on how networks connect to each other. For example, data packets containing information that determine whether they will stay on the LAN or will be sent to a remote network, like the internet.
the transport layer
The transport layer includes protocols to control the flow of traffic across a network. These protocols permit or deny communication with other devices and include information about the status of the connection. Activities of this layer include error control, which ensures data is flowing smoothly across the network.
the application layer.
Finally, at the application layer, protocols determine how the data packets will interact with receiving devices. Functions that are organized at application layer include file transfers and email services.
_______________. The ________ shares error information and status updates of data packets. This is useful for detecting and troubleshooting network errors. The ______ reports information about packets that were dropped or that disappeared in transit, issues with network connectivity, and packets redirected to other routers.
Internet Control Message Protocol (ICMP)
The _____________ is responsible for delivering data between two systems or networks and includes protocols to control the flow of traffic across a network. TCP and UDP are the two transport protocols that occur at this layer.
transport layer
The __________________ is an internet communication protocol that allows two devices to form a connection and stream data. It ensures that data is reliably transmitted to the destination service. ______ contains the port number of the intended destination service, which resides in the TCP header of a TCP/IP packet.
Transmission Control Protocol (TCP)
The _________________ is a connectionless protocol that does not establish a connection between devices before transmissions. It is used by applications that are not concerned with the reliability of the transmission. Data sent over UDP is not tracked as extensively as data sent using TCP. Because UDP does not establish network connections, it is used mostly for performance sensitive applications that operate in real time, such as video streaming.
User Datagram Protocol (UDP)
The __________ in the TCP/IP model is similar to the application, presentation, and session layers of the OSI model. The ___________ is responsible for making network requests or responding to requests. This layer defines which internet services and applications any user can access. Protocols in the application layer determine how the data packets will interact with receiving devices. Some common protocols used on this layer are:
Hypertext transfer protocol (HTTP)
Simple mail transfer protocol (SMTP)
Secure shell (SSH)
File transfer protocol (FTP)
Domain name system (DNS)
Application layer protocols rely on underlying layers to transfer the data across the network.
application layer
An ______________, or _________ is a unique string of characters that identifies a location of a device on the internet. Each device on the internet has a unique ___________, just like every house on a street has its own mailing address.
internet protocol address IP address
A __________ is a unique alphanumeric identifier that is assigned to each physical device on a network. When a switch receives a data packet, it reads the MAC address of the destination device and maps it to a port. It then keeps this information in a MAC address table. Think of the MAC address table like an address book that the switch uses to direct data packets to the appropriate device.
MAC address
The maximum data transmission capacity over a network, measured by bits per second
Bandwidth:
The practice of using remote servers, application, and network services that are hosted on the internet instead of on local physical devices
Cloud computing:
A collection of servers or computers that stores resources and data in remote data centers that can be accessed via the internet
Cloud network:
A basic unit of information that travels from one device to another within a network
Data packet:
A network device that broadcasts information to every device on the network
Hub:
A set of standards used for routing and addressing data packets as they travel between devices on a network
Internet Protocol (IP):
A unique string of characters that identifies the location of a device on the internet
Internet Protocol (IP) address:
A network that spans small areas like an office building, a school, or a home
Local Area Network (LAN):
A unique alphanumeric identifier that is assigned to each physical device on a network
Media Access Control (MAC) address:
A device that connects your router to the internet and brings internet access to the LAN
Modem:
Network: A group of connected devices
Network:
A standardized concept that describes the seven layers computers use to communicate and send data over the network
Open systems interconnection (OSI) model:
The practice of capturing and inspecting data packets across a network
Packet sniffing:
A software-based location that organizes the sending and receiving of data between devices on a network
Port:
A network device that connects multiple networks together
Router:
A device that makes connections between specific devices on a network by sending and receiving data between them
Switch:
A framework used to visualize how data is organized and transmitted across a network
TCP/IP model:
An internet communication protocol that allows two devices to form a connection and stream data
Transmission Control Protocol (TCP):
A connectionless protocol that does not establish a connection between devices before transmissions
User Datagram Protocol (UDP):
A network that spans a large geographic area like a city, state, or country
Wide Area Network (WAN):
Communication protocols
Communication protocols govern the exchange of information in network transmission. They dictate how the data is transmitted between devices and the timing of the communication. They also include methods to recover data lost in transit. Here are a few of them.
- Transmission Control Protocol (TCP)
- User Datagram Protocol (UDP)
- Hypertext Transfer Protocol (HTTP)
- Domain Name System (DNS)
___________________ is an internet communication protocol that allows two devices to form a connection and stream data. ____ uses a three-way handshake process. First, the device sends a synchronize (SYN) request to a server. Then the server responds with a SYN/ACK packet to acknowledge receipt of the device’s request. Once the server receives the final ACK packet from the device, a _____ connection is established. In the TCP/IP model, ______ occurs at the transport layer.
Transmission Control Protocol (TCP)
___________________ is a connectionless protocol that does not establish a connection between devices before a transmission. This makes it less reliable than TCP. But it also means that it works well for transmissions that need to get to their destination quickly. For example, one use of ____ is for internet gaming transmissions. In the TCP/IP model, ______ occurs at the transport layer.
User Datagram Protocol (UDP)
__________________ is an application layer protocol that provides a method of communication between clients and website servers. _______ uses port 80. _____ is considered insecure, so it is being replaced on most websites by a secure version, called ____(s) However, there are still many websites that use the insecure _____ protocol. In the TCP/IP model, _____ occurs at the application layer.
Hypertext Transfer Protocol (HTTP)
__________________ is a protocol that translates internet domain names into IP addresses. When a client computer wishes to access a website domain using their internet browser, a query is sent to a dedicated _____ server. The ______ server then looks up the IP address that corresponds to the website domain. _____ normally uses UDP on port 53. However, if the _____ reply to a request is large, it will switch to using the TCP protocol. In the TCP/IP model, _____ occurs at the application layer.
Domain Name System (DNS)
Management Protocols
The next category of network protocols is management protocols. Management protocols are used for monitoring and managing activity on a network. They include protocols for error reporting and optimizing performance on the network.
- Simple Network Management Protocol (SNMP)
- Internet Control Message Protocol (ICMP)
__________________ is a network protocol used for monitoring and managing devices on a network. SNMP can reset a password on a network device or change its baseline configuration. It can also send requests to network devices for a report on how much of the network’s bandwidth is being used up. In the TCP/IP model, SNMP occurs at the application layer.
Simple Network Management Protocol (SNMP)
________________________ is an internet protocol used by devices to tell each other about data transmission errors across the network. ICMP is used by a receiving device to send a report to the sending device about the data transmission. ICMP is commonly used as a quick way to troubleshoot network connectivity and latency by issuing the “ping” command on a Linux operating system. In the TCP/IP model, ICMP occurs at the internet layer.
Internet Control Message Protocol (ICMP)
Security Protocols
Security protocols are network protocols that ensure that data is sent and received securely across a network. Security protocols use encryption algorithms to protect data in transit. Below are some common security protocols.
- Hypertext Transfer Protocol Secure (HTTPS)
- Secure File Transfer Protocol (SFTP)
____________________is in the management family of network protocols. DHCP is an application layer protocol used on a network to configure devices. It assigns a unique IP address and provides the addresses of the appropriate DNS server and default gateway for each device. DHCP servers operate on UDP port 67 while DHCP clients operate on UDP port 68.
Dynamic Host Configuration Protocol (DHCP)
The devices on your local home or office network each have a private IP address that they use to communicate directly with each other. In order for the devices with private IP addresses to communicate with the public internet, they need to have a public IP address. Otherwise, responses will not be routed correctly. Instead of having a dedicated public IP address for each of the devices on the local network, the router can replace a private source IP address with its public IP address and perform the reverse operation for responses. This process is known as Network Address Translation (NAT) and it generally requires a router or firewall to be specifically configured to perform NAT. NAT is a part of layer 2 (internet layer) and layer 3 (transport layer) of the TCP/IP model.
Network Address Translation
By now, you are familiar with IP and MAC addresses. You’ve learned that each device on a network has both an IP address that identifies it on the network and a MAC address that is unique to that network interface. A device’s IP address may change over time, but its MAC address is permanent. _________________ (ARP) is mainly a network access layer protocol in the TCP/IP model used to translate the IP addresses that are found in data packets into the MAC address of the hardware device.
Each device on the network performs ARP and keeps track of matching IP and MAC addresses in an ARP cache. ARP does not have a specific port number.
Address Resolution Protocol
__________ is an application layer protocol that allows a device to communicate with another device or server. _______ sends all information in clear text. It uses command line prompts to control another device similar to secure shell (SSH), but ________ is not as secure as SSH. Telnet can be used to connect to local or remote devices and uses TCP port 23.
Telnet