
Prestige 661H/HW Series User’s Guide
Chapter 11 Firewalls
134
Figure 58
Three-Way Handshake
Under normal circumstances, the application that initiates a session sends a SYN
(synchronize) packet to the receiving server. The receiver sends back an ACK
(acknowledgment) packet and its own SYN, and then the initiator responds with an ACK
(acknowledgment). After this handshake, a connection is established.
•
SYN Attack
floods a targeted system with a series of SYN packets. Each packet causes
the targeted system to issue a SYN-ACK response. While the targeted system waits for
the ACK that follows the SYN-ACK, it queues up all outstanding SYN-ACK responses
on what is known as a backlog queue. SYN-ACKs are moved off the queue only when an
ACK comes back or when an internal timer (which is set at relatively long intervals)
terminates the three-way handshake. Once the queue is full, the system will ignore all
incoming SYN requests, making the system unavailable for legitimate users.
Figure 59
SYN Flood
• In a
LAND Attack
, hackers flood SYN packets into the network with a spoofed source
IP address of the targeted system. This makes it appear as if the host computer sent the
packets to itself, making the system unavailable while the target system tries to respond
to itself.
7
A
brute-force
attack, such as a "Smurf" attack, targets a feature in the IP specification
known as directed or subnet broadcasting, to quickly flood the target network with
useless data. A Smurf hacker floods a router with Internet Control Message Protocol
Содержание Prestige 661H Series
Страница 37: ...Prestige 661H HW Series User s Guide 37 List of Tables...
Страница 41: ...Prestige 661H HW Series User s Guide 41 Introduction to DSL...
Страница 51: ...Prestige 661H HW Series User s Guide 51 Chapter 1 Getting To Know Your Prestige...
Страница 67: ...Prestige 661H HW Series User s Guide 67 Chapter 3 Wizard Setup for Internet Access...
Страница 81: ...Prestige 661H HW Series User s Guide 81 Chapter 5 LAN Setup...
Страница 125: ...Prestige 661H HW Series User s Guide 125 Chapter 8 Network Address Translation NAT Screens...
Страница 143: ...Prestige 661H HW Series User s Guide 143 Chapter 11 Firewalls...
Страница 151: ...Prestige 661H HW Series User s Guide 151 Chapter 12 Firewall Configuration Figure 64 Firewall Edit Rule...
Страница 165: ...Prestige 661H HW Series User s Guide 165 Chapter 12 Firewall Configuration...
Страница 169: ...Prestige 661H HW Series User s Guide 169 Chapter 13 Content Filtering...
Страница 175: ...Prestige 661H HW Series User s Guide 175 Chapter 14 Introduction to IPSec...
Страница 203: ...Prestige 661H HW Series User s Guide 203 Chapter 15 VPN Screens...
Страница 207: ...Prestige 661H HW Series User s Guide 207 Chapter 16 Remote Management Configuration...
Страница 221: ...Prestige 661H HW Series User s Guide 221 Chapter 17 Universal Plug and Play UPnP...
Страница 227: ...Prestige 661H HW Series User s Guide 227 Chapter 18 Logs Screens...
Страница 241: ...Prestige 661H HW Series User s Guide 241 Chapter 19 Media Bandwidth Management Advanced Setup...
Страница 265: ...Prestige 661H HW Series User s Guide 265 Chapter 21 Maintenance...
Страница 275: ...Prestige 661H HW Series User s Guide 275 Chapter 23 Menu 1 General Setup...
Страница 279: ...Prestige 661H HW Series User s Guide 279 Chapter 24 Menu 2 WAN Backup Setup...
Страница 283: ...Prestige 661H HW Series User s Guide 283 Chapter 25 Menu 3 LAN Setup...
Страница 287: ...Prestige 661H HW Series User s Guide 287 Chapter 26 Wireless LAN Setup...
Страница 293: ...Prestige 661H HW Series User s Guide 293 Chapter 27 Internet Access...
Страница 307: ...Prestige 661H HW Series User s Guide 307 Chapter 29 Static Route Setup...
Страница 311: ...Prestige 661H HW Series User s Guide 311 Chapter 30 Bridging Setup...
Страница 327: ...Prestige 661H HW Series User s Guide 327 Chapter 31 Network Address Translation NAT...
Страница 343: ...Prestige 661H HW Series User s Guide 343 Chapter 33 Filter Configuration...
Страница 363: ...Prestige 661H HW Series User s Guide 363 Chapter 36 System Information and Diagnosis...
Страница 375: ...Prestige 661H HW Series User s Guide 375 Chapter 37 Firmware and Configuration File Maintenance...
Страница 381: ...Prestige 661H HW Series User s Guide 381 Chapter 38 System Maintenance...
Страница 385: ...Prestige 661H HW Series User s Guide 385 Chapter 39 Remote Management...
Страница 395: ...Prestige 661H HW Series User s Guide 395 Chapter 40 IP Policy Routing...
Страница 399: ...Prestige 661H HW Series User s Guide 399 Chapter 41 Call Scheduling...
Страница 411: ...Prestige 661H HW Series User s Guide 411 Chapter 42 VPN IPSec Setup...
Страница 415: ...Prestige 661H HW Series User s Guide 415 Chapter 43 SA Monitor...
Страница 427: ...Prestige 661H HW Series User s Guide 427 Chapter 44 Troubleshooting Figure 275 Security Setting ActiveX Controls...
Страница 431: ...Prestige 661H HW Series User s Guide 431 Appendix A...
Страница 451: ...Prestige 661H HW Series User s Guide 451 Appendix C IP Subnetting...
Страница 455: ...Prestige 661H HW Series User s Guide 455 Appendix E Command Interpreter...
Страница 461: ...Prestige 661H HW Series User s Guide 461 Appendix F Firewall Commands...
Страница 464: ...Prestige 661H HW Series User s Guide Appendix G NetBIOS Filter Commands 464...
Страница 465: ...Prestige 661H HW Series User s Guide 465 Appendix G NetBIOS Filter Commands...
Страница 478: ...Prestige 661H HW Series User s Guide Appendix H VPN Setup 478 ftp 5631148 bytes sent in 614 8Seconds 9 17Kbytes sec...
Страница 479: ...Prestige 661H HW Series User s Guide 479 Appendix H VPN Setup...
Страница 482: ...Prestige 661H HW Series User s Guide Appendix I Splitters and Microfilters 482...
Страница 483: ...Prestige 661H HW Series User s Guide 483 Appendix I Splitters and Microfilters...
Страница 537: ...Prestige 661H HW Series User s Guide 537 Appendix M Internal SPTGEN...