Networking Flashcards
UDP Name
User Datagram Protocol
UDP Protocol
- Connectionless
- No formal open or close to the connection
- “Unreliable” delivery
- No error recovery
- No reordering of data or retransmissions
- No flow control
- Sender determines the amount of data transmitted
TCP & UDP
- Transported inside of IP
- Encapsulated by the IP protocol
- Two ways to move data from place to place
- Different features for different applications
- OSI Layer 4
- The transport layer
- Multiplexing
- Use many different applications at the same time
TCP Name
Transmission Control Protocol
TCP Protocol
- Connection-oriented
- A formal connection setup and close
- “Reliable” delivery
- Recovery from errors
- Can manage out-of-order messages or retransmissions
- Flow control
- The receiver can manage how much data is sent
IPv4 sockets
Server IP address, protocol,
server application port number
• Client IP address, protocol, client port number
Non-ephemeral ports
permanent port numbers
• Ports 0 through 1,023
Ephemeral ports
– temporary port numbers
• Ports 1,024 through 65,535
• Determined in real-time by the client
FTP Name
File Transfer Protocol
FTP Protocol
- tcp/20 (active mode data), tcp/21 (control)
- Transfers files between systems
- Authenticates with a username and password
- Some systems use a generic/anonymous login
- Full-featured functionality
- List, add, delete, etc.
SSH Name
Secure Shell
SSH Protocol
- Encrypted communication link - tcp/22
* Looks and acts the same as Telnet
Telnet
- Telnet – Telecommunication Network - tcp/23
- Login to devices remotely
- Console access
- In-the-clear communication
- Not the best choice for production systems
SMTP Name
Simple Mail Transfer Protocol
SMTP Protocol
• Server to server email transfer - tcp/25
• Also used to send mail from a device to a mail server
• Commonly configured on mobile devices
and email clients
DNS Name
Domain Name System
DNS Protocol
- Converts names to IP addresses - udp/53
- www.professormesser.com = 162.159.246.164
- These are very critical resources
- Usually multiple DNS servers are in production
HTTP & HTTPS
- Hypertext Transfer Protocol - tcp/80
- Communication in the browser
- And by other applications
- In the clear or encrypted - HTTPS - tcp/443
- Supported by nearly all web servers and clients
RDP Name
Remote Desktop Protocol
RDP Name
Remote Desktop Protocol
RDP Protocol
• Share a desktop from a remote location over tcp/3389
• Remote Desktop Services on many Windows versions
• Can connect to an entire desktop
or just an application
• Clients for Windows, macOS, Linux, Unix,
iPhone, Android, and others
SMB Name
Server Message Block
SMB Protocol
• Direct over tcp/445 (NetBIOS-less)
• Direct SMB communication over TCP
without the NetBIOS transport.
- Protocol used by Microsoft Windows
- File sharing, printer sharing
- Also called CIFS (Common Internet File System)
NetBIOS name services
udp/137 Register, remove, and find windows services by name.
NetBIOS Datagram service
udp/138 Windows connection-less data transfer
NetBIOS Session Service
tcp/139 Windows connection oriented data transfer.
AFP Name
Apple Filing Protocol
AFP Protocol
- File services in macOS
- tcp/548
- Works with SLP (Service Location Protocol)
- tcp/427 and udp/427
- Populates the list of available devices
- File management
- Copy, move, delete files
DHCP Name
- Dynamic Host Configuration Protocol
DHCP Protocol
• Automated configuration of IP address, subnet mask
and other options
• udp/67, udp/68
• Requires a DHCP server
• Server, appliance, integrated into a SOHO router, etc.
• Dynamic / pooled
• IP addresses are assigned in real-time from a pool
• Each system is given a lease and must renew
at set intervals
• DHCP reservation
• Addresses are assigned by MAC address
in the DHCP server
• Quickly manage addresses from one location
LDAP Name
(Lightweight Directory Access Protocol)
LDAP Protocol
tcp/389
• Store and retrieve information in a network directory
• Commonly used in Microsoft Active Directory
SNMP Name
Simple Network Management Protocol
SNMP Protocol
- Gather statistics/ metrics from network devices to manage devices.
- Queries: udp/161
- Traps: udp/162
- v1 – The original
- Structured tables, in-the-clear
- v2 – A good step ahead
- Data type enhancements
- Bulk transfers, still in-the-clear
- v3 – A secure standard
- Message integrity
- Authentication, encryption
ASIC
Application-specific integrated circuit
802.11a
5 Ghz 54megabits per second (Mbit/s) 1/3 range of 2.4 Ghz
802.11b
2.4 Ghz 11 megabits (Mbits/s)
Frequency conflict. 22 Mhz channel
802.11g
2.Ghz 54 megabits (Mbits/s)
Frequency conflict. 20 Mhz channel
802.11n
• Operates at 5 GHz and/or 2.4 GHz • 40 MHz channel widths • 600 megabits per second (Mbit/s) • 40 MHz mode and 4 antennas • 802.11n uses 4 MIMO • Multiple-input multiple-output • Multiple transmit and receive antennas 4MIMO 150Mbit/s 600 Mbit/s 20 or 40 Mhz (bonded)
802.11ac
• Operates in the 5 GHz band
• Less crowded, more frequencies
(up to 160 MHz channel bandwidth)
• Increased channel bonding - Larger bandwidth usage
• Denser signaling modulation - Faster data transfers
• 8 MU-MIMO streams
• Twice as many streams as 802.11n
8MU-MIMO 866.7Mbit/s ~6.8 Gbit/s
40Mhz for 802.11n stations
80 Mhz for 802.11ac stations
160 Mhz optional.
Zigbee
- Internet of Things networking
- Open standard - IEEE 802.15.4 PAN
- Alternative to WiFi and Bluetooth
- Longer distances than Bluetooth
- Less power consumption than WiFi
- Mesh network of all Zigbee devices in your home
- Light switch communicates to light bulbs
- Tell Amazon Echo to lock the door
- Uses the ISM band
- Industrial, Scientific, and Medical
- 900 MHz and 2.4 GHz frequencies in the US
Z-Wave
• Proprietary home automation networking • Internet of Things (IoT) • Control lights, locks, garage doors, etc. • Wireless mesh networking • Nodes can hop through other nodes on the way to the destination • Uses the ISM band • Industrial, Scientific, and Medical • 900 MHz frequencies in the US • No conflicts with 802.11
• The fundamental network device • Every device on the network has a NIC • Computers, servers, printers, routers, switches, phones, tablets, cameras, etc. • Specific to the network type • Ethernet, WAN, wireless, etc. • Often built-in to the motherboard • Or added as an expansion card • Many options • Single port, multi-port, copper, fiber
Network Interface Card (NIC)
Receive signal, regenerate, resend • No forwarding decisions to make • Common use • Boost copper or fiber connections • Convert one network media to another • Extend wireless network reach
Repeater
- “Multi-port repeater”
- Traffic going in one port is repeated to every other port
- Everything is half-duplex
- Becomes less efficient as network speeds increase
- 10 megabit / 100 megabit
- Difficult to find today
Hub
• Imagine a switch with two to four ports
• Makes forwarding decisions in software
• Connects different physical networks
• Can connect different topologies
• Gets around physical network size limitations /
collisions
• Distributes traffic based on MAC address
• A modern bridge is a wireless access point
• Bridges wired Ethernet to wireless
Bridge
- Bridging done in hardware
- Application-specific integrated circuit (ASIC)
- Forwards traffic based on data link address
- Many ports and features
- The core of an enterprise network
- May provide Power over Ethernet (PoE)
- Multilayer switch - Includes routing functionality
Switches
- Very few configuration options
- Plug and play
- Fixed configuration
- No VLANs
- Very little integration with other devices
- No management protocols
- Low price point
- Simple is less expensive
Unmanaged switches
- VLAN support
- Interconnect with other switches via 802.1Q
- Traffic prioritization
- Voice traffic gets a higher priority
- Redundancy support
- Spanning Tree Protocol (STP)
- External management
- Simple Network Management Protocol (SNMP)
- Port mirroring
- Capture packets
Managed Switches
• Routes traffic between IP subnets
• Makes forwarding decisions based on IP address
• Routers inside of switches sometimes called
“layer 3 switches”
• Often connects diverse network types
• LAN, WAN, copper, fiber
Routers
