CompTIA Security+ 学习指南
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2020-01-24
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Professor Messer’s
CompTIA Security+
SY0-401 Study Guide
hp://www.ProfessorMesser.com
Network Devices
© 2014 Messer Studios, LLC
hp://www.ProfessorMesser.com
Professor Messer’s CompTIA SY0-401 Security+ Study Guide - Page 1
Switch
• An OSI layer 2 device
• Hardware bridging ASICs (very fast!)
• Forwards trac based on MAC address
• The core of an enterprise network
• High bandwidth - Many simultaneous packets
Router
• An OSI layer 3 device
• Routes trac between IP subnets
• Routers inside of switches are somemes
called “layer 3 switches”
• Layer 2 = Switch, Layer 3 = Router
• Oen connects diverse network types -
LAN, WAN, copper, ber
Firewall
• OSI layer 4 (TCP/UDP), some rewalls lter
through OSI layer 7
• Filters trac by port number
• Can encrypt trac into/out of the network
and between sites
• Can proxy trac - A common security technique
• Most rewalls can be layer 3 devices (routers)
Load balancer
• Distributes the load over many physical servers
• Very common in large environments
Proxy
• Sits between the users and the external network
• Receives the user requests and sends
the request on their behalf (the proxy)
• Applicaons may need to know how to
use the proxy (explicit)
• Some proxies are invisible (transparent)
All-in-one security appliance
• Unied Threat Management (UTM) /
Web security gateway
• URL lter / Content inspecon, malware
inspecon, spam lter, CSU/DSU, router, switch,
rewall, IDS/IPS, bandwidth shaper, VPN endpoint
VPN concentrator
• The connecon point
for remote users
• Trac is encrypted across the
Internet and decrypted on the
internal private network
Intrusion detecon/prevenon system
• Protects against OS and applicaon exploits
• Detecon
• Alerts but does not stop the aack
• Prevenon
• Blocks the aack
Protocol analyzer
• Captures network packets
• Decodes each part of the communicaon
• Sees all of the network conversaon
Spam Filters
• Stop unsolicited email at the gateway
• Whitelist
• Only receive email from trusted senders
• SMTP standards checking
• Block anything that doesn’t follow RFC standards
• rDNS - Reverse DNS
• Block email where the sender’s domain doesn’t match
the IP address
• Tarping
• Intenonally slow down the server conversaon
• Recipient ltering
• Block all email not addressed to a valid
recipient email address
Web Applicaon Firewall
• Applies rules to HTTP conversaons
• Allow or deny based on expected input
• Protects against exploits like SQL injecons
and buer overows
• Focus of Payment Card Industry Data
Security Standard (PCI DSS)
Applicaon-aware Security Devices
• Network-based Firewalls
• Control trac ows based on the applicaon
• Microso SQL Server, Twier, YouTube
• Intrusion Prevenon Systems
• Idenfy the applicaon
• Apply applicaon-specic vulnerability signatures
to the trac
• Host-based rewalls
• Work with the OS to determine the applicaon
Version 0x04
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