802.11g HomePlug AV ADSL2+ Gateway User's Guide
Table Of Contents
- User’s Guide
- Introduction
- Introducing the P-660HWP-Dx
- Introducing the Web Configurator
- 2.1 Web Configurator Overview
- 2.2 Accessing the Web Configurator
- 2.2.1 User Access
- 2.2.2 Administrator Access
- 2.3 Resetting the P-660HWP-Dx
- 2.3.1 Using the Reset Button
- 2.4 Navigating the Web Configurator
- 2.4.1 Navigation Panel
- 2.4.2 Status Screen
- 2.4.3 Status: Any IP Table
- 2.4.4 Status: WLAN Status
- 2.4.5 Status: Bandwidth Status
- 2.4.6 Status: Powerline Statistics
- 2.4.7 Status: Packet Statistics
- 2.4.8 Changing Login Password
- Wizards
- Network
- WAN Setup
- 5.1 WAN Overview
- 5.1.1 Encapsulation
- 5.1.2 Multiplexing
- 5.1.3 Encapsulation and Multiplexing Scenarios
- 5.1.4 VPI and VCI
- 5.1.5 IP Address Assignment
- 5.1.6 Nailed-Up Connection (PPP)
- 5.1.7 NAT
- 5.2 Metric
- 5.3 Traffic Shaping
- 5.3.1 ATM Traffic Classes
- 5.4 Zero Configuration Internet Access
- 5.5 Internet Connection
- 5.5.1 Configuring Advanced Internet Connection Setup
- 5.6 Configuring More Connections
- 5.6.1 More Connections Edit
- 5.6.2 Configuring More Connections Advanced Setup
- 5.7 Traffic Redirect
- 5.8 Configuring WAN Backup
- LAN Setup
- 6.1 LAN Overview
- 6.1.1 LANs, WANs and the P-660HWP-Dx
- 6.1.2 DHCP Setup
- 6.1.3 DNS Server Address
- 6.1.4 DNS Server Address Assignment
- 6.2 LAN TCP/IP
- 6.2.1 IP Address and Subnet Mask
- 6.2.2 RIP Setup
- 6.2.3 Multicast
- 6.2.4 Any IP
- 6.3 Configuring LAN IP
- 6.3.1 Configuring Advanced LAN Setup
- 6.4 DHCP Setup
- 6.5 LAN Client List
- 6.6 LAN IP Alias
- Wireless LAN
- 7.1 Wireless Network Overview
- 7.2 Wireless Network Setup
- 7.2.1 Requirements
- 7.2.2 Setup Information
- 7.3 Wireless Security Overview
- 7.3.1 SSID
- 7.3.2 MAC Address Filter
- 7.3.3 User Authentication
- 7.3.4 Encryption
- 7.3.5 One-Touch Intelligent Security Technology (OTIST)
- 7.4 General Wireless LAN Screen
- 7.4.1 No Security
- 7.4.2 WEP Encryption
- 7.4.3 WPA-PSK/WPA2-PSK
- 7.4.4 WPA/WPA2
- 7.4.5 Wireless LAN Advanced Setup
- 7.5 OTIST
- 7.5.1 Enabling OTIST
- 7.5.2 Starting OTIST
- 7.5.3 Notes on OTIST
- 7.6 MAC Filter
- 7.7 WMM QoS
- 7.7.1 WMM QoS Example
- 7.7.2 WMM QoS Priorities
- 7.7.3 Services
- 7.8 QoS Screen
- 7.8.1 ToS (Type of Service) and WMM QoS
- 7.8.2 Application Priority Configuration
- Powerline
- Network Address Translation (NAT)
- 9.1 NAT Overview
- 9.1.1 NAT Definitions
- 9.1.2 What NAT Does
- 9.1.3 How NAT Works
- 9.1.4 NAT Application
- 9.1.5 NAT Mapping Types
- 9.2 SUA (Single User Account) Versus NAT
- 9.3 SIP ALG
- 9.4 NAT General Setup
- 9.5 Port Forwarding
- 9.5.1 Default Server IP Address
- 9.5.2 Port Forwarding: Services and Port Numbers
- 9.5.3 Configuring Servers Behind Port Forwarding (Example)
- 9.6 Configuring Port Forwarding
- 9.6.1 Port Forwarding Rule Edit
- 9.7 Address Mapping
- 9.7.1 Address Mapping Rule Edit
- WAN Setup
- Security
- Firewalls
- 10.1 Firewall Overview
- 10.2 Types of Firewalls
- 10.2.1 Packet Filtering Firewalls
- 10.2.2 Application-level Firewalls
- 10.2.3 Stateful Inspection Firewalls
- 10.3 Introduction to ZyXEL’s Firewall
- 10.3.1 Denial of Service Attacks
- 10.4 Denial of Service
- 10.4.1 Basics
- 10.4.2 Types of DoS Attacks
- 10.5 Stateful Inspection
- 10.5.1 Stateful Inspection Process
- 10.5.2 Stateful Inspection and the P-660HWP-Dx
- 10.5.3 TCP Security
- 10.5.4 UDP/ICMP Security
- 10.5.5 Upper Layer Protocols
- 10.6 Guidelines for Enhancing Security with Your Firewall
- 10.6.1 Security In General
- 10.7 Packet Filtering Vs Firewall
- 10.7.1 Packet Filtering:
- 10.7.2 Firewall
- Firewall Configuration
- 11.1 Access Methods
- 11.2 Firewall Policies Overview
- 11.3 Rule Logic Overview
- 11.3.1 Rule Checklist
- 11.3.2 Security Ramifications
- 11.3.3 Key Fields For Configuring Rules
- 11.4 Connection Direction
- 11.4.1 LAN to WAN Rules
- 11.4.2 Alerts
- 11.5 General Firewall Policy
- 11.6 Firewall Rules Summary
- 11.6.1 Configuring Firewall Rules
- 11.6.2 Customized Services
- 11.6.3 Configuring a Customized Service
- 11.7 Example Firewall Rule
- 11.8 Predefined Services
- 11.9 Anti-Probing
- 11.10 DoS Thresholds
- 11.10.1 Threshold Values
- 11.10.2 Half-Open Sessions
- 11.10.3 Configuring Firewall Thresholds
- Content Filtering
- Certificates
- 13.1 Certificates Overview
- 13.1.1 Advantages of Certificates
- 13.2 Self-signed Certificates
- 13.3 Verifying a Certificate
- 13.3.1 Checking the Fingerprint of a Certificate on Your Computer
- 13.4 Configuration Summary
- 13.5 My Certificates
- 13.6 My Certificates > Details
- 13.7 My Certificates > Create
- 13.8 My Certificates > Import
- 13.8.1 Certificate File Formats
- 13.9 Trusted CAs
- 13.10 Trusted CA Details
- 13.11 Trusted CA > Import
- 13.12 Trusted Remote Hosts
- 13.13 Trusted Remote Hosts > Import
- 13.14 Trusted Remote Host Certificate Details
- 13.15 Directory Servers
- 13.16 Directory Server Add or Edit
- Firewalls
- Advanced
- Static Route
- Bandwidth Management
- 15.1 Bandwidth Management Overview
- 15.2 Application-based Bandwidth Management
- 15.3 Subnet-based Bandwidth Management
- 15.4 Application and Subnet-based Bandwidth Management
- 15.5 Scheduler
- 15.5.1 Priority-based Scheduler
- 15.5.2 Fairness-based Scheduler
- 15.6 Maximize Bandwidth Usage
- 15.6.1 Reserving Bandwidth for Non-Bandwidth Class Traffic
- 15.6.2 Maximize Bandwidth Usage Example
- 15.6.3 Bandwidth Management Priorities
- 15.7 Over Allotment of Bandwidth
- 15.8 Configuring Summary
- 15.9 Bandwidth Management Rule Setup
- 15.10 DiffServ
- 15.10.1 DSCP and Per-Hop Behavior
- 15.10.2 Rule Configuration
- 15.11 Bandwidth Monitor
- Dynamic DNS Setup
- Remote Management Configuration
- 17.1 Remote Management Overview
- 17.1.1 Remote Management Limitations
- 17.1.2 Remote Management and NAT
- 17.1.3 System Timeout
- 17.2 WWW
- 17.3 Telnet
- 17.4 Configuring Telnet
- 17.5 Configuring FTP
- 17.6 SNMP
- 17.6.1 Supported MIBs
- 17.6.2 SNMP Traps
- 17.6.3 Configuring SNMP
- 17.7 Configuring DNS
- 17.8 Configuring ICMP
- 17.9 TR-069
- Universal Plug-and-Play (UPnP)
- 18.1 Introducing Universal Plug and Play
- 18.1.1 How do I know if I'm using UPnP?
- 18.1.2 NAT Traversal
- 18.1.3 Cautions with UPnP
- 18.2 UPnP and ZyXEL
- 18.2.1 Configuring UPnP
- 18.3 Installing UPnP in Windows Example
- 18.3.1 Installing UPnP in Windows Me
- 18.3.2 Installing UPnP in Windows XP
- 18.4 Using UPnP in Windows XP Example
- 18.4.1 Auto-discover Your UPnP-enabled Network Device
- 18.4.2 Web Configurator Easy Access
- Maintenance and Troubleshooting
- Appendices and Index

Chapter 10 Firewalls
P-660HWP-Dx User’s Guide
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10.4.2 Types of DoS Attacks
There are four types of DoS attacks:
1 Those that exploit bugs in a TCP/IP implementation.
2 Those that exploit weaknesses in the TCP/IP specification.
3 Brute-force attacks that flood a network with useless data.
4 IP Spoofing.
5 "Ping of Death" and "Teardrop" attacks exploit bugs in the TCP/IP implementations of
various computer and host systems.
• Ping of Death uses a "ping" utility to create an IP packet that exceeds the maximum
65,536 bytes of data allowed by the IP specification. The oversize packet is then sent to an
unsuspecting system. Systems may crash, hang or reboot.
• Teardrop attack exploits weaknesses in the re-assembly of IP packet fragments. As data is
transmitted through a network, IP packets are often broken up into smaller chunks. Each
fragment looks like the original IP packet except that it contains an offset field that says,
for instance, "This fragment is carrying bytes 200 through 400 of the original (non
fragmented) IP packet." The Teardrop program creates a series of IP fragments with
overlapping offset fields. When these fragments are reassembled at the destination, some
systems will crash, hang, or reboot.
6 Weaknesses in the TCP/IP specification leave it open to "SYN Flood" and "LAND"
attacks. These attacks are executed during the handshake that initiates a communication
session between two applications.
Figure 93 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.