Prestige 2602HW Series User’s Guide
Chapter 13 Firewalls
153
Figure 61
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 62
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
(ICMP) echo request packets (pings). Since the destination IP address of each packet is
the broadcast address of the network, the router will broadcast the ICMP echo request
packet to all hosts on the network. If there are numerous hosts, this will create a large
Содержание Prestige 2602HW Series
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Страница 40: ...Prestige 2602HW Series User s Guide 40 Introduction to DSL...
Страница 72: ...Prestige 2602HW Series User s Guide 72 Chapter 4 Password Setup...
Страница 102: ...Prestige 2602HW Series User s Guide 102 Chapter 6 Wireless LAN Setup...
Страница 112: ...Prestige 2602HW Series User s Guide 112 Chapter 7 WAN Setup...
Страница 124: ...Prestige 2602HW Series User s Guide 124 Chapter 8 Network Address Translation NAT Screens...
Страница 130: ...Prestige 2602HW Series User s Guide 130 Chapter 9 Introduction to VoIP...
Страница 142: ...Prestige 2602HW Series User s Guide 142 Chapter 10 Voice Screens...
Страница 148: ...Prestige 2602HW Series User s Guide 148 Chapter 12 Time and Date...
Страница 162: ...Prestige 2602HW Series User s Guide 162 Chapter 13 Firewalls...
Страница 192: ...Prestige 2602HW Series User s Guide 192 Chapter 16 Remote Management Configuration...
Страница 206: ...Prestige 2602HW Series User s Guide 206 Chapter 17 Universal Plug and Play UPnP...
Страница 212: ...Prestige 2602HW Series User s Guide 212 Chapter 18 Logs Screens...
Страница 214: ...Prestige 2602HW Series User s Guide 214 Chapter 19 Maintenance Figure 102 System Status...
Страница 224: ...Prestige 2602HW Series User s Guide 224 Chapter 19 Maintenance...
Страница 232: ...Prestige 2602HW Series User s Guide 232 Chapter 20 Introducing the SMT...
Страница 236: ...Prestige 2602HW Series User s Guide 236 Chapter 21 Menu 1 General Setup...
Страница 240: ...Prestige 2602HW Series User s Guide 240 Chapter 22 Menu 2 WAN Backup Setup...
Страница 244: ...Prestige 2602HW Series User s Guide 244 Chapter 23 Menu 3 LAN Setup...
Страница 248: ...Prestige 2602HW Series User s Guide 248 Chapter 24 Wireless LAN Setup...
Страница 254: ...Prestige 2602HW Series User s Guide 254 Chapter 25 Internet Access...
Страница 268: ...Prestige 2602HW Series User s Guide 268 Chapter 27 Static Route Setup...
Страница 272: ...Prestige 2602HW Series User s Guide 272 Chapter 28 Bridging Setup...
Страница 288: ...Prestige 2602HW Series User s Guide 288 Chapter 29 Network Address Translation NAT...
Страница 304: ...Prestige 2602HW Series User s Guide 304 Chapter 31 Filter Configuration...
Страница 324: ...Prestige 2602HW Series User s Guide 324 Chapter 34 System Information and Diagnosis...
Страница 340: ...Prestige 2602HW Series User s Guide 340 Chapter 35 Firmware and Configuration File Maintenance...
Страница 345: ...Prestige 2602HW Series User s Guide Chapter 36 System Maintenance 345 24 hour intervals after starting...
Страница 346: ...Prestige 2602HW Series User s Guide 346 Chapter 36 System Maintenance...
Страница 350: ...Prestige 2602HW Series User s Guide 350 Chapter 37 Remote Management...
Страница 362: ...Prestige 2602HW Series User s Guide 362 Chapter 39 Call Scheduling...
Страница 366: ...Prestige 2602HW Series User s Guide 366 Chapter 40 Internal SPTGEN...
Страница 372: ...Prestige 2602HW Series User s Guide 372 Chapter 41 Troubleshooting...
Страница 376: ...Prestige 2602HW Series User s Guide 376 Appendix A Hardware Specifications...
Страница 396: ...Prestige 2602HW Series User s Guide 396 Appendix C IP Subnetting...
Страница 402: ...Prestige 2602HW Series User s Guide 402 Appendix E Wireless LAN and IEEE 802 11...
Страница 409: ...Prestige 2602HW Series User s Guide Appendix H Triangle Route 409...
Страница 410: ...Prestige 2602HW Series User s Guide 410 Appendix H Triangle Route...
Страница 434: ...Prestige 2602HW Series User s Guide 434 Appendix J Command Interpreter...
Страница 436: ...Prestige 2602HW Series User s Guide 436 Appendix K Firewall Commands...