1101 Flashcards
• The power source when unplugged
– May be easily replaced or require a tear down
– Five minutes vs. one hour
• Lithium-Ion (Li-ion) and
– Lithium-Ion polymer (LiPo) are common
– No “memory effect”
– Charging the battery diminishes capacity
• Different form factor for each laptop
– Battery types and styles can vary
– Battery technology is changing constantly
Laptop batteries
• The most-used component of the laptop – Can be easy to replace – A few screws and a single ribbon cable – May not always be this simple • Or connect an external USB keyboard – Not very portable, but works in a pinch
Laptop keyboard
• Some repairs might require the removal or
replacement of a key cap
– This can be a delicate procedure
• Check with the manufacturer’s instructions
– It’s very easy to accidentally break the key cap
or the components underneath
Laptop keys
• Small Outline Dual In-line Memory Module (SO-DIMM)
• Memory used in laptops and mobile devices
– Often easy to install and replace
• Some laptop memory is soldered to the system board
– No upgrade available
– Requires a full system board replacement
Laptop memory
• Magnetic disk
– Traditional spinning drive platters
– 2.5 form factors (3.5 inch for desktops)
Laptop storage
– All memory, no moving parts
– Silent, fast access time, less latency
– 2.5 inch form factors
SSD (Solid-state drive)
– Smaller form factor
– No SATA data or power cables
– Easy to install and replace
M.2
• All internal – Open a cover on the back – Open the entire laptop • Can be very modular – Two screws and the drive slides out • M.2 drives are even easier – One screw - similar to RAM installation
Replacing laptop storage
• An impressive upgrade – Move from spinning mechanical drive to solid state memory – It’s almost like getting a new laptop • Install an OS on the SSD – Move user documents between drives – Install any required applications – Can be time consuming • Image/clone the HDD – No OS installation required – Move everything from one to the other • Imaging software needed – Sometimes included with the SSD – Many commercial and open source options • Create an image file - One drive at a time • Drive-to-drive image – Image directly from one drive to the other
Migrating from HDD to SSD
Wireless network connectivity – Connect without wires • 802.11 – Local area network (LAN) – High speed, Internet access • Bluetooth – Personal area network (PAN) - Short range – Connect peripherals and other nearby devices
802.11 wireless and Bluetooth
• Sign in or unlock your laptop with a
fingerprint reader or face recognition
– Something you are
• Requires additional configuration in the OS
– Hardware required for most options
• Relatively secure
– Faces and fingerprints are quite unique
Biometrics
• Short-distance networking
– 4 centimeters or less
– Data transfers or authentication
• Common on mobile phones and smart watches
– Payment method on your wrist
• Use it for authentication without typing a password
– Hospital workstations, warehouses, manufacturing
Near-field communication (NFC)
• Liquid crystal display – Light shines through liquid crystals • Advantages – Lightweight – Relatively low power – Relatively inexpensive • Disadvantages – Black levels are a challenge – Requires separate backlight – Florescent, LED, etc. – Lights are difficult to replace
Portable LCD
• TN (Twisted Nematic) LCD – The original LCD technology – Fast response times (gaming!) – Poor viewing angles - color shifts • IPS (In Plane Switching) LCD – Excellent color representation – More expensive to produce than TN • VA (Vertical Alignment) LCD – A good compromise between TN and IPS – Good color representation – Slower response times than TN
LCD technologies
• Organic Light Emitting Diode – Organic compound emits light when receiving an electric current • Thinner and lighter – Flexible and mobile - no glass needed • No backlight – The organic compound provides the light • Tablets, phones, smart watches – Very accurate color representation – A bit higher cost than LCD
OLED
• Multiple antennas
– WiFi main and aux / Bluetooth
• Antenna wires wrap around the laptop screen
– It’s up high!
Wi-Fi antennas
• Video capture - Built-in camera and microphone
• Usually includes both audio and video
– Specialized drivers and software
Webcam
• Built-in to the laptop display
– Useful for video calls
• Not good for non-casual use
– Analog or USB microphones can help
Microphone
– Backlight is LEDs instead of florescent
– LEDs around the edge of the screen
– An array of LEDs behind the screen
– The latest laptops are LED-backlit
LED backlighting
CCFL - Cold Cathode – Fluorescent Lamp – Higher voltage and power needed – Added thickness to the display – No longer a common backlight – Older laptops will use these
Fluorescent
LCD displays need a backlight
– Florescent lamp/LED to LCD display to your eyes
• Some laptops have inverters - Turn DC into AC
• Verify backlight
– Look closely and use a flashlight
• May need to replace the LCD inverter or display
– Choose carefully
Backlight and inverter
Use a pen-like device as input
– Stylus input - Useful for graphical input
• Used commonly on laptop / tablets
– Or hybrid devices
Digitizer
• Merge laptop and tablet input
– Digitizer responds to touch - No keyboard required
• But often still available
– Many options for input - Use the best one for the job
Touchscreen
• Universal Serial Bus – High-speed wired communication – Used for charging and data transfers • Micro-USB – A smaller USB connection – Common now worldwide • Older devices may use Mini-USB – Slightly larger
USB
• 24-pin double-sided USB connector – Used for both hosts and devices • Acts as a USB 2.0/3.0/3.1/4 connection – Different signals can use the same connector • Can transmit other signals – DisplayPort, HDMI, Thunderbolt
USB-C
• Apple proprietary – 8-pin digital signals – iPhone and iPad devices • Some advantages over Micro-USB – Higher power output for phones and tablets – Can be inserted either way – Simpler design
Lightning
• DB-9 - also called DE-9 • Commonly used for RS-232 signals – Recommended Standard 232 – An industry standard since 1969 • Serial communications standard – Traditionally used for modem connections • Now used as a configuration port – Switches, routers, firewalls, etc – Use a USB to DB-9 converter cable
Serial interfaces
– Send small amounts of data wirelessly over a limited area • Built into your phone – Payment systems, transportation,in-person information exchange • Access token, identity “card” – Short range with encryption support
NFC
• High speed communication over short distances – PAN (Personal Area Network) • Connects our mobile devices – Smartphones – Tethering – Headsets and headphones – Health monitors – Automobile and phone integration – Smartwatches – External speakers
Bluetooth
• Turn your phone into a WiFi hotspot – Your own personal wireless router – Extend the cellular data network to all of your devices • Dependent on phone type and provider – May require additional charges and data costs
Hotspot
• Touchscreen pen / touch screen stylus / capacitive stylus
– Activate the interface without actually touching it
• Handwriting
– Note taking, signatures
• Precise selection
– Easier to see the screen
Touch pens
• Digital stylus
– A more advanced writing tool
• The stylus communicates directly to the device
– Pressure sensitivity, programmable buttons, etc.
• Must be compatible with the tablet
– e.g., Apple iPad uses an Apple Pencil
Active stylus
• Use an active stylus with an external digitizer
– Very precise input
Drawing pad
Replace the mouse – Useful in tight working areas – Common on laptops • External options – Battery powered – Bluetooth connected • Drag and tap – Or use multiple finger input for right-clicking, zooming, and window control • Enable and disable – Avoid inadvertent mouse clicks and movements
Trackpad
• Hands-free audio - Earphones and microphone • Wired – USB connections are common on laptops – Connects to 3.5 mm TRRS (tip-ring-ring-sleeve) connector – Analog audio jack – iPhone can use Lightning port • Wireless - Bluetooth headsets
Headsets
- Mobile audio - Battery powered
- Wireless connection - Bluetooth link
- Stereo sound - Small package
Speakers
– Use external keyboard and mouse – Extend existing laptop interfaces – Add additional functionality – Desktop adapter cards – Avoid cable issues
Docking station
– Similar to a docking station
– Does not commonly have an expansion card option
– Usually connects using USB
Port replicator
Global System for Mobile Communications
– Mobile networking standard
1.4 - Cellular Standards
• 90% of the market
– Originally an EU standard
– Worldwide coverage
• Used by AT&T and T-Mobile in the United States
– Move your SIM card (Subscriber Identity Module) from
phone to phone
• Original GSM standard used multiplexing
– Everyone gets a little slice of time
GSM
• Code Division Multiple Access
– Everyone communicates at the same time
– Each call uses a different code
– The codes are used to filter each call on the receiving side
• Used by Verizon and Sprint
– Handsets are controlled by the network provider
– Not much adoption elsewhere
CDMA
• 3rd Generation – Introduced in 1998 • Upgraded data connectivity over 2G – Incremental 3G updates improved speeds – Usually several megabits per second • Bandwidth improvement allowed new functionality – GPS – Mobile television – Video on demand – Video conferencing
3G technology
• Long Term Evolution (LTE)
– A “4G” technology
– Converged standard (GSM and CDMA providers)
– Based on GSM and EDGE
(Enhanced Data Rates for GSM Evolution)
– Standard supports download rates of 150 Mbit/s
• LTE Advanced (LTE-A)
– Standard supports download rates of 300 Mbit/s
4G and LTE
• Fifth generation cellular networking – Launched worldwide in 2020 • Significant performance improvements – At higher frequencies – Eventually 10 gigabits per second – Slower speeds from 100-900 Mbit/s • Significant IoT impact – Bandwidth becomes less of a constraint – Larger data transfers – Faster monitoring and notification – Additional cloud processing
5G
• PRL (Preferred Roaming List) updates
– CDMA networks (i.e., Verizon, Sprint)
• Allows your phone to connect to the right tower
– Can be updated over the air (OTA)
Updates
• Turn your phone into a WiFi hotspot
– Your own personal wireless router
– Extend the cellular data network to all of your devices
• Dependent on phone type and provider
– May require additional charges and data costs
Hotspot
• Connect a Bluetooth device – Built-in security - Use or verify a PIN • Pair the devices one time – Future connections should be automatic • Check with the manufacturer – May prefer a specific sequence – Discoverable mode isn’t always obvious
Bluetooth pairing
• Enable Bluetooth on both devices – Android and iOS: Settings / Bluetooth • Set devices to discoverable mode – May require key sequence on Bluetooth device • Select discovered device – Many devices may appear! • Enter or confirm PIN – Should be the same on both devices • Test connectivity – Devices should now communicate
Bluetooth pairing process
Created by the U.S. Department of Defense
– Over 30 satellites currently in orbit
• Precise navigation - Need to see at least 4 satellites
• Determines location based on timing differences
– Longitude, latitude, altitude
• Mobile device location services and geotracking
– Maps, directions
– Determine physical location based on
GPS, WiFi, and cellular towers
GPS (Global Positioning System)
• Manage company-owned and user-owned mobile devices
– BYOD - Bring Your Own Device
• Centralized management of the mobile devices
– Specialized functionality
• Set policies on apps, data, camera, etc.
– Control the remote device
– The entire device or a “partition”
• Manage access control
– Force screen locks and PINs on these single user devices
MDM (Mobile Device Management)
• Corporate email configuration
– User does not need to configure anything
– The MDM makes the changes on the device
– Account details, server address, communication method
• Two-factor authentication
– Require specific authentication types
– Biometrics, pseudo-random authentication app
• Corporate applications
– Allow or restrict app installation
– Prevent unauthorized app usage
MDM configurations
• Many settings are preconfigured – Telephone / Text messaging • Email – Everyone handles email services differently – Corporate email configurations can vary • Data synchronization – Based on data rates and speeds – Important for backup and recovery
Configuring a mobile device
• Outlook, Exchange – Microsoft’s email service – Usually the same for Hotmail and Outlook.com • Authenticate to Microsoft 365 – Username, password • Select the items to synchronize – Changes in Outlook will appear on the mobile device • Same process for Google Workspace – Formerly known as G Suite
Microsoft 365
• Integrated into iOS and iPadOS
– Provide an iCloud username and password
• Select synchronization options
– Extensive customization
• Synchronize to macOS
– Use your desktop, laptop, or mobile device
iCloud
• Data types – Mail – Pictures, music, video – Calendar – Contacts • Data caps and transfer costs – Cellular vs 802.11 – Enable or disable network connections – Control the use of cellular downloads
Synchronizing data
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 and UDP
TCP and UDP
• 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
TCP – Transmission Control Protocol
• Connectionless - No formal open/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
UDP – User Datagram Protocol
• Real-time communication
– There’s no way to stop and resend the data
– Time doesn’t stop for your network
• Connectionless protocols
– DHCP (Dynamic Host Configuration Protocol)
– TFTP (Trivial File Transfer Protocol)
UDP
• Connection-oriented protocols prefer a “return receipt”
– HTTPS (Hypertext Transfer Protocol Secure)
– SSH (Secure Shell)
• The application doesn’t worry about out of order
frames or missing data
– TCP handles all of the communication overhead
– The application has one job
TCP
– Server IP address, protocol,
server application port number
– Client IP address, protocol, client port number
• IPv4 sockets
– Ports 0 through 1,023
– Usually on a server or service
Non-ephemeral ports – permanent port numbers
– temporary port numbers
– Ports 1,024 through 65,535
– Determined in real-time by the client
Ephemeral ports
• Well-known port number
– Client and server need to match
• Important for firewall rules - Port-based security
• A bit of rote memorization
– Becomes second nature after a while
• Make sure you know port number, protocol,
and how the protocol is used
Port numbers
• 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.
FTP - File Transfer Protocol
- Encrypted communication link - tcp/22
* Looks and acts the same as Telnet
SSH - Secure Shell
Telnet – Telecommunication Network - tcp/23
• Login to devices remotely
– Console access
• In-the-clear communication
– Not the best choice for production systems
Telnet
• SMTP - Simple Mail Transfer 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
• Other protocols are used for clients to receive email
– IMAP, POP3
SMTP - Simple Mail Transfer 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
DNS - Domain Name System
• 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
– Manage addresses from one location
DHCP - Dynamic Host Configuration Protocol
• Hypertext Transfer Protocol – Communication in the browser – And by other applications • In the clear or encrypted – Supported by nearly all web servers and clients
HTTP and HTTPS
• Receive emails from an email server – Authenticate and transfer • POP3 - Post office Protocol version 3 – tcp/110 – Basic mail transfer functionality • IMAP4 - Internet Message Access Protocol v4 – tcp/143 – Includes email inbox management from multiple clients
POP3 / IMAP
• Protocol used by Microsoft Windows
– File sharing, printer sharing
– Also called CIFS (Common Internet File System)
SMB - Server Message Block
udp/137 - NetBIOS name services (nbname)
tcp/139 - NetBIOS session service (nbsession)
Using NetBIOS over TCP/IP
Direct SMB communication over TCP without
the NetBIOS transport
Direct over tcp/445 (NetBIOS-less)
• Gather statistics from network 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
SNMP - Simple Network Management Protocol
• LDAP (Lightweight Directory Access Protocol) - tcp/389
• Store and retrieve information in a network directory
– Commonly used in Microsoft Active Directory
LDAP
• 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
RDP - Remote Desktop Protocol
tcp/20, tcp/21 Sends and receives files between systems
FTP
tcp/22 Encrypted console access
SSH
udp/137
NetBIOS
NetBIOS
tcp/139
SMB
tcp/445
tcp/443
HTTPS
tcp/389
LDAP
tcp/3389
RDP
• 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
• 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) • Port mirroring – Capture packets • External management – Simple Network Management Protocol (SNMP)
Managed switches
• Not a wireless router
– A wireless router is a router and an access point
in a single device
• An access point is a bridge
– Extends the wired network onto the wireless network
– Makes forwarding decisions based on MAC address
Access point
• Combination of punch-down blocks and
RJ-45 connectors
• Runs from desks are made once
– Permanently punched down to patch panel
• Patch panel to switch can be easily changed
– No special tools
– Use existing cables
Patch Panels
• Filters traffic by port number
– OSI layer 4 (TCP/UDP)
– Some firewalls can filter based on the application
• Can encrypt traffic into/out of the network
– Protect your traffic between sites
• Can proxy traffic
– A common security technique
• Most firewalls can be layer 3 devices (routers)
– Usually sits on the ingress/egress of the network
Firewalls
• Power provided on an Ethernet cable
– One wire for both network and electricity
– Phones, cameras, wireless access points
– Useful in difficult-to-power areas
• Power provided at the switch
– Built-in power - Endspans
– In-line power injector - Midspans
Power over Ethernet (PoE)
• Power over Ethernet
– Commonly marked on the switch or interfaces
PoE switch
• “Multi-port repeater”
– Traffic going in one port is repeated to
every other port
• Everything is half-duplex
• Becomes less efficient as network traffic increases
• 10 megabit / 100 megabit
• Difficult to find today
Hub
• Broadband – Transmission across multiple frequencies – Different traffic types • Data on the “cable” network – DOCSIS (Data Over Cable Service Interface Specification) • High-speed networking – Speeds up to 1 Gigabit/s are available • Multiple services – Data, voice, video
Cable modem
• ADSL (Asymmetric Digital Subscriber Line)
– Uses telephone lines
• Download speed is faster than the upload
speed (asymmetric)
– ~10,000 foot limitation from the central office (CO)
– 52 Mbit/s downstream / 16 Mbit/s upstream are
common
– Faster speeds may be possible if closer to the CO
DSL modem
• Optical network terminal
– Fiber to the premises
• Connect the ISP fiber network to the copper network
– Demarcation point (demarc) in the data center
– Terminal box on the side of the building
• Line of responsibility
– One side of the box is the ISP
– Other side of the box is your network
ONT
• 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)
• Networking devices have different functional planes of operation – Data, control, and management planes • Split the functions into separate logical units – Extend the functionality and management of a single device – Perfectly built for the cloud • Infrastructure layer / Data plane – Process the network frames and packets – Forwarding, trunking, encrypting, NAT • Control layer / Control plane – Manages the actions of the data plane – Routing tables, session tables, NAT tables – Dynamic routing protocol updates • Application layer / Management plane – Configure and manage the device – SSH, browser, API
SDN (Software Defined Networking)
• One of the original 802.11 wireless standards
– October 1999
• Operates in the 5 GHz range
– Or other frequencies with special licensing
• 54 megabits per second (Mbit/s)
• Smaller range than 802.11b
– Higher frequency is absorbed by objects in the way
• Not commonly seen today
802.11a
• Also an original 802.11 standard - October 1999 • Operates in the 2.4 GHz range • 11 megabits per second (Mbit/s) • Better range than 802.11a, less absorption problems • More frequency conflict – Baby monitors, cordless phones, microwave ovens, Bluetooth • Not commonly seen today
802.11b
- An “upgrade” to 802.11b - June 2003
- Operates in the 2.4 GHz range
- 54 megabits per second (Mbit/s) - Similar to 802.11a
- Backwards-compatible with 802.11b
- Same 2.4 GHz frequency conflict problems as 802.11b
802.11g
• The update to 802.11g, 802.11b, and 802.11a – October 2009 • 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 MIMO – Multiple-input multiple-output – Multiple transmit and receive antennas
802.11n (Wi-Fi 4)
• Approved in January 2014 – Significant improvements over 802.11n • 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 • Eight MU-MIMO downlink streams – Twice as many streams as 802.11n – Nearly 7 gigabits per second
802.11ac (Wi-Fi 5)
• Approved in February 2021
– The successor to 802.11ac/Wi-Fi 5
• Operates at 5 GHz and/or 2.4 GHz
– 20, 40, 80, and 160 MHz channel widths
• 1,201 megabits per second per channel
– A relatively small increase in throughput
– Eight bi-directional MU-MIMO streams
• Orthogonal frequency-division multiple access (OFDMA)
– Works similar to cellular communication
– Improves high-density installations
802.11ax (Wi-Fi 6)
• Wireless access point in a house with the stock antennas
– You might get a range of 40 to 50 meters
• Try connecting two buildings located miles from each other
– Fixed directional antennas and increased signal strength
• Outdoors
– Minimal signal absorption or bounce
• Directional antennas
– Focused, point-to-point connection
• Wireless regulations are complex
– Refer to your country’s regulatory agency
• Frequency use
– Unlicensed 2.4 GHz or 5 GHz frequencies
– Additional frequencies may be available
– Additional licensing may be required
• Signal strength
– Indoor and outdoor power is usually regulated
• Outdoor antenna installation is not trivial
– Get an expert, be safe
Long-range fixed wireless
• It’s everywhere – Access badges – Inventory/Assembly line tracking – Pet/Animal identification – Anything that needs to be tracked • Radar technology – Radio energy transmitted to the tag – RF powers the tag, ID is transmitted back – Bidirectional communication – Some tag formats can be active/powered
RFID (Radio-frequency identification)
• Two-way wireless communication – Builds on RFID, which is mostly one-way • Payment systems – Major credit cards, online wallets • Bootstrap for other wireless – NFC helps with Bluetooth pairing • Access token, identity “card” – Short range with encryption support
NFC (Near field communication)
• Frequency – 2.4 GHz or 5 GHz – And sometimes both • Channels – Groups of frequencies, numbered by the IEEE – Non-overlapping channels would be ideal • Regulations – Most countries have regulations to manage frequency use – Spectrum use, power output, interference requirements, etc.
802.11 technologies
• Remove the wires – Headsets, speakers, keyboards / mice • Uses the 2.4 GHz range – Unlicensed ISM (Industrial, Scientific and Medical) band – Same as 802.11 • Short-range – Most consumer devices operate to about 10 meters – Industrial Bluetooth devices can communicate over 100 meters
Bluetooth
• Domain Name System
– Convert names to IP addresses
– And vice versa
• Distributed naming system
– The load is balanced across many different servers
• Usually managed by the ISP or IT department
– A critical resource
DNS server
• Dynamic Host Configuration Protocol – Automatic IP address configuration • Very common service – Available on most home routers • Enterprise DHCP will be redundant – Usually running on central servers
DHCP server
• Centralized storage of documents,spreadsheets, videos, pictures, and any other files – A fileshare • Standard system of file management – SMB (Server Message Block), Apple Filing Protocol (AFP), etc. • The front-end hides the protocol – Copy, delete, rename, etc.
File server
• Connect a printer to the network
– Provide printing services for all network devices
• May be software in a computer
– Computer is connected to the printer
• May be built-in to the printer
– Network adapter and software
• Uses standard printing protocols
– SMB (Server Message Block), IPP (Internet
Printing Protocol), LPD (Line Printer Daemon)
Print server
• Store your incoming mail
– Send your outgoing mail
• Usually managed by the ISP or the IT department
– A complex set of requirements
• Usually one of the most important services
– 24 x 7 support
Mail server
• Standard for message logging – Diverse systems, consolidated log • Usually a central logging receiver – Integrated into the SIEM • You’re going to need a lot of disk space – No, more. More than that.
Syslog
• Respond to browser requests
– Using standard web browsing protocols - HTTP/HTTPS
– Pages are built with HTML, HTML5
• Web pages are stored on the server
– Downloaded to the browser
– Static pages or built dynamically in real-time
Web server
• Login authentication to resources – Centralized management • Almost always an enterprise service – Not required on a home network • Usually a set of redundant servers – Always available – Extremely important service
Authentication server
Unsolicited messages – Email, forums, etc. • Various content – Commercial advertising – Non-commercial proselytizing – Phishing attempts • Significant technology issue – Security concerns, resource utilization, storage costs, managing the spam
Spam
• Unsolicited email
– Stop it at the gateway before it reaches the user
– On-site or cloud-based
Spam gateways
• Next-generation firewall, Unified Threat Management (UTM) / Web security gateway • URL filter / Content inspection • Malware inspection • Spam filter • CSU/DSU • Router, Switch • Firewall • IDS/IPS • Bandwidth shaper • VPN endpoint
All-in-one security appliance
• Distribute the load – Multiple servers – Invisible to the end-user • Large-scale implementations – Web server farms, database farms • Fault tolerance – Server outages have no effect - Very fast convergence
Load balancers
- Configurable load - Manage across servers
- TCP offload - Protocol overhead
- SSL offload - Encryption/Decryption
- Caching - Fast response
- Prioritization - QoS
- Content switching - Application-centric balancing
Load balancer features
• An intermediate server
– Client makes the request to the proxy
– The proxy performs the actual request
– The proxy provides results back to the client
• Useful features
– Access control, caching, URL filtering, content scanning
Proxy server
• Supervisory Control and Data Acquisition System
– Large-scale, multi-site Industrial Control Systems (ICS)
• PC manages equipment
– Power generation, refining,
manufacturing equipment
– Facilities, industrial, energy, logistics
• Distributed control systems
– Real-time information
– System control
– Requires extensive segmentation
– No access from the outside
SCADA / ICS
• Legacy systems – Another expression for “really old” – May also be “really important” – Learning old things can be just as important as learning the new things • Embedded systems – Purpose-built device – Not usual to have direct access to the operating system – Alarm system, door security, time card system
Legacy and embedded systems
• Appliances – Refrigerators • Smart devices – Smart speakers respond to voice commands • Air control – Thermostats, temperature control • Access – Smart doorbells • May require a segmented network – Limit any security breaches
IoT (Internet of Things) devices
• Internet Protocol version 4
– OSI Layer 3 address
IPv4 addresses
• Internet Protocol v6 - 128-bit address
– 340,282,366,920,938,463,463,374,607,431,768,211,456
addresses (340 undecillion)
– 6.8 billion people could each have
5,000,000,000,000,000,000,000,000,000 addresses
IPv6 addresses
IP Address, e.g., 192.168.1.165
– Every device needs a unique IP address
• Subnet mask, e.g., 255.255.255.0
– Used by the local device to determine its subnet
– The subnet mask isn’t (usually) transmitted
across the network
• Default gateway, e.g., 192.168.1.1
– The router that allows you to communicate
outside of your local subnet
– The default gateway must be an IP address
on the local subnet
Networking with IPv4
• We remember names – professormesser.com, google.com, youtube.com • Internet routers don’t know names – Routers only know IP addresses • Something has to translate between names and IP addresses – Domain Name Services • You configure two DNS servers in your IP configuration – That’s how important it is
DNS servers
• Translates human-readable names into computer-readable IP addresses – You only need to remember www.ProfessorMesser.com • Hierarchical – Follow the path • Distributed database – Many DNS servers – 13 root server clusters (over 1,000 actual servers) – Hundreds of generic top-level domains (gTLDs) - .com, .org, .net, etc. – Over 275 country code top-level domains (ccTLDs) - .us, .ca, .uk, etc.
Domain Name System
• Resource Records (RR)
– The database records of domain name services
• Over 30 record types
– IP addresses, certificates, host alias names, etc.
• These are important and critical configurations
– Make sure to check your settings, backup, and test!
DNS records
• Defines the IP address of a host – This is the most popular query • A records are for IPv4 addresses – Modify the A record to change the host name to IP address resolution • AAAA records are for IPv6 addresses – The same DNS server, different records
Address records (A) (AAAA)
• Determines the host name for the mail server - this isn’t an IP address; it’s a name
Mail exchanger record (MX)
Human-readable text information – Useful public information – Was originally designed for informal information • Can be used for verification purposes – If you have access to the DNS, then you must be the administrator of the domain name • Commonly used for email security – External email servers validate information from your DNS
Text records (TXT)
• SPF protocol
– A list of all servers authorized to send emails
for this domain
– Prevent mail spoofing
– Mail servers perform a check to see if incoming mail
really did come from an authorized host
Sender Policy Framework (SPF)
• Digitally sign a domain’s outgoing mail
– Validated by mail servers, not usually
seen by the end user
– The public key is in the DKIM TXT record
Domain Keys Identified Mail (DKIM)
Domain-based Message Authentication, Reporting,
and Conformance (DMARC)
– Prevent unauthorized email use (spoofing)
– An extension of SPF and DKIM
• You decide what external email servers should do with
emails that don’t validate through SPF or DKIM
– That policy is written into a DMARC TXT record
– Accept all, send to spam, or reject the email
– Compliance reports can be sent to the email administrator
DMARC
• IP address range – And excluded addresses • Subnet mask • Lease durations • Other scope options – DNS server – Default gateway – VOIP servers
Scope properties
• Grouping of IP addresses – Each subnet has its own scope – 192.168.1.0/24 – 192.168.2.0/24 – 192.168.3.0/24 • A scope is generally a single contiguous pool of IP addresses – DHCP exceptions can be made inside of the scope
DHCP pools
• Dynamic assignment
– DHCP server has a big pool of addresses to give out
– Addresses are reclaimed after a lease period
• Automatic assignment
– Similar to dynamic allocation
– DHCP server keeps a list of past assignments
– You’ll always get the same IP address
DHCP address assignment
• Address reservation – Administratively configured • Table of MAC addresses – Each MAC address has a matching IP address • Other names – Static DHCP Assignment, Static DHCP, Static Assignment, IP Reservation
DHCP address allocation
Leasing your address – It’s only temporary – But it can seem permanent • Allocation – Assigned a lease time by the DHCP server – Administratively configured • Reallocation – Reboot your computer – Confirms the lease
DHCP leases
• T1 timer – Check in with the lending DHCP server to renew the IP address – 50% of the lease time (by default) • T2 timer – If the original DHCP server is down, try rebinding with any DHCP server – 87.5% of the lease time (7/8ths)
DHCP renewal
Local Area Networks
• A group of devices in the same broadcast domain
LANs
- Virtual Local Area Networks
- A group of devices in the same broadcast domain
- Separated logically instead of physically
Virtual LANs
• Virtual Local Area Networks
– A group of devices in
the same broadcast domain
Configuring VLANs
• Virtual Private Networks – Encrypted (private) data traversing a public network • Concentrator – Encryption/decryption access device – Often integrated into a firewall • Many deployment options – Specialized cryptographic hardware – Software-based options available
VPNs
• On-demand access from a remote device
– Software connects to a VPN concentrator
• Some software can be configured as always-on
Client-to-Site VPNs
• Communication to a satellite
– Non-terrestrial communication
• High cost relative to terrestrial networking
– 50 Mbit/s down, 3 Mbit/s up are common
– Remote sites, difficult-to-network sites
• High latency
– 250 ms up, 250 ms down
– Starlink advertises 40 ms and is working on 20 ms
• High frequencies - 2 GHz
– Line of sight, rain fade
Satellite networking
• High speed data communication – Frequencies of light • Higher installation cost than copper – Equipment is more costly – More difficult to repair – Communicate over long distances • Large installation in the WAN core – Supports very high data rates – SONET, wavelength division multiplexing • Fiber is slowly approaching the premises – Business and home use
Fiber
• Broadband
– Transmission across multiple frequencies
– Different traffic types
• Data on the “cable” network
– DOCSIS (Data Over Cable Service Interface
Specification)
• High-speed networking
– 50 Mbits/s through 1,000+ Mbit/s are common
• Multiple services
– Data, voice, video
Cable broadband
• ADSL (Asymmetric Digital Subscriber Line)
– Uses telephone lines
• Download speed is faster than the upload speed
(asymmetric)
– 200 Mbit/s downstream / 20 Mbit/s upstream
are common
– ~10,000 foot limitation from the central office (CO)
– Faster speeds may be possible if closer to the CO
DSL
• Mobile devices – “Cell” phones • Separate land into “cells” – Antenna coverages a cell with certain frequencies • Tethering – Turn your phone into a wireless router • Mobile hotspot – Standalone devices – Use your phone for other things
Cellular networks
• Wireless Internet Service Provider – Terrestrial internet access using wireless • Connect rural or remote locations – Internet access for everyone • Many different deployment technologies – Meshed 802.11 – 5G home internet – Proprietary wireless • Need an outdoor antenna – Speeds can range from ~ 10 to 1,000 megabits per second
WISP
• Local Area Network – Local is relative • A building or group of buildings – High-speed connectivity • Ethernet and 802.11 wireless – Any slower and it isn’t “local”
LAN
• Wide Area Network – Spanning the globe • Generally connects LANs across a distance – And generally much slower than the LAN • Many different WAN technologies – Point-to-point serial, MPLS, etc. – Terrestrial and non-terrestrial
WAN
• Personal Area Network – Your own private network – Bluetooth, IR, NFC • Automobile – Audio output – Integrate with phone • Mobile phone - Wireless headset • Health – Workout telemetry, daily reports
PAN
• Metropolitan Area Network – A network in your city – Larger than a LAN, often smaller than a WAN • Historically MAN-specific topologies – Metro Ethernet • Common to see government ownership – They “own” the right-of-way
MAN
• Storage Area Network (SAN)
– Looks and feels like a local storage device
– Block-level access
– Very efficient reading and writing
• Requires a lot of bandwidth
– May use an isolated network and high-speed
network technologies
SAN
• Wireless LAN – 802.11 technologies • Mobility – Within a building – In a limited geographical area • Expand coverage with additional access points – Downtown area – Large campus
WLAN
• “Pinch” the connector onto a wire – Coaxial, twisted pair, fiber • Connect the modular connector to the Ethernet cable – The final step of the process • Metal prongs are pushed through the insulation – The plug is also permanently pressed onto the cable sheath
Cable crimper
• Wireless networks are incredibly easy to monitor – Everyone “hears” everything • Purpose-built hardware or mobile device add-on – Specializes in 802.11 analysis • Identify errors and interference – Validate antenna location and installation
WiFi analyzer
• Where does that wire go? – Follow the tone • Tone generator – Puts an analog sound on the wire • Inductive probe – Doesn’t need to touch the copper – Hear through a small speaker
Tone generator
