802.11g Wireless 4-port Router User's Guide
Table Of Contents
- User’s Guide
- Copyright
- Federal Communications Commission (FCC) Interference Statement
- ZyXEL Limited Warranty
- Customer Support
- Table of Contents
- List of Figures
- List of Tables
- Preface
- Getting to Know Your ZyAIR
- 1.1 Introducing the ZyAIR
- 1.2 ZyAIR Features
- 1.2.1 Physical Features
- 1.2.2 Firmware Features
- 1.2.2.1 Internal RADIUS Server
- 1.2.2.2 Wi-Fi Protected Access
- 1.2.2.3 802.11b Wireless LAN Standard
- 1.2.2.4 802.11g Wireless LAN Standard
- 1.2.2.5 STP (Spanning Tree Protocol) / RSTP (Rapid STP)
- 1.2.2.6 Certificates
- 1.2.2.7 Limit the number of Client Connections
- 1.2.2.8 SSL Passthrough
- 1.2.2.9 Firewall
- 1.2.2.10 Brute-Force Password Guessing Protection
- 1.2.2.11 Wireless LAN MAC Address Filtering
- 1.2.2.12 WEP Encryption
- 1.2.2.13 IEEE 802.1X Network Security
- 1.2.2.14 Universal Plug and Play (UPnP)
- 1.2.2.15 Dynamic DNS Support
- 1.2.2.16 PPPoE Support (RFC2516)
- 1.2.2.17 PPTP Encapsulation
- 1.2.2.18 Network Address Translation (NAT)
- 1.2.2.19 Traffic Redirect
- 1.2.2.20 NAT for Single-IP-address Internet Access
- 1.2.2.21 DHCP (Dynamic Host Configuration Protocol)
- 1.2.2.22 Multicast
- 1.2.2.23 IP Alias
- 1.2.2.24 IP Policy Routing
- 1.2.2.25 SNMP
- 1.2.2.26 Full Network Management
- 1.2.2.27 Logging and Tracing
- 1.2.2.28 Diagnostics Capabilities
- 1.2.2.29 Embedded FTP and TFTP Servers
- 1.2.2.30 Wireless Association List
- 1.2.2.31 Wireless LAN Channel Usage
- 1.3 Applications for the ZyAIR
- Introducing the Web Configurator
- Wizard Setup
- System Screens
- LAN Screens
- Wireless Configuration and Roaming
- Wireless Security
- 7.1 Wireless Security Overview
- 7.2 Security Parameters Summary
- 7.3 WEP Overview
- 7.4 Configuring WEP Encryption
- 7.5 Introduction to WPA
- 7.6 Configuring WPA-PSK Authentication
- 7.7 Wireless Client WPA Supplicants
- 7.8 Configuring WPA Authentication
- 7.9 Introduction to RADIUS
- 7.10 Configuring RADIUS
- 7.11 802.1x Overview
- 7.12 Dynamic WEP Key Exchange
- 7.13 Configuring 802.1x and Dynamic WEP Key Exchange
- 7.14 Configuring 802.1x and Static WEP Key Exchange
- 7.15 Configuring 802.1x
- 7.16 MAC Filter
- Internal RADIUS Server
- WAN
- Single User Account (SUA) / Network Address Translation (NAT)
- Static Route Screens
- Remote Management Screens
- UPnP
- Firewalls
- Firewall Screens
- Content Filtering
- Certificates
- 17.1 Certificates Overview
- 17.2 Self-signed Certificates
- 17.3 Configuration Summary
- 17.4 My Certificates
- 17.5 Certificate File Formats
- 17.6 Importing a Certificate
- 17.7 Creating a Certificate
- 17.8 My Certificate Details
- 17.9 Trusted CAs
- 17.10 Importing a Trusted CA’s Certificate
- 17.11 Trusted CA Certificate Details
- Log Screens
- Maintenance
- Introducing the SMT
- General Setup
- Menu 2 WAN Setup
- LAN Setup
- Internet Access
- Remote Node Configuration
- Static Route Setup
- Dial-in User Setup
- Network Address Translation (NAT)
- Filter Configuration
- Enabling the Firewall
- SNMP Configuration
- System Security
- System Information and Diagnosis
- Firmware and Configuration File Maintenance
- System Maintenance and Information
- Remote Management
- Call Scheduling
- Appendix A
- Appendix B
- Appendix C
- Appendix D
- Appendix E
- Appendix F
- Appendix G
- Appendix H
- Appendix I
- Appendix J
- Appendix K
- Appendix L
- Index
ZyAIR G-2000 Plus User’s Guide
Chapter 14 Firewalls 188
14.5.5 Upper Layer Protocols
Some higher layer protocols (such as FTP and RealAudio) utilize multiple network
connections simultaneously. In general terms, they usually have a "control connection" which
is used for sending commands between endpoints, and then "data connections" which are used
for transmitting bulk information.
Consider the FTP protocol. A user on the LAN opens a control connection to a server on the
Internet and requests a file. At this point, the remote server will open a data connection from
the Internet. For FTP to work properly, this connection must be allowed to pass through even
though a connection from the Internet would normally be rejected.
In order to achieve this, the ZyAIR inspects the application-level FTP data. Specifically, it
searches for outgoing "PORT" commands, and when it sees these; it adds a cache entry for the
anticipated data connection. This can be done safely, since the PORT command contains
address and port information, which can be used to uniquely identify the connection.
Any protocol that operates in this way must be supported on a case-by-case basis. You can use
the web configurator’s Custom Services feature to do this.
14.6 Guidelines For Enhancing Security With Your Firewall
1 Change the default password via SMT or web configurator.
2 Think about access control before you connect a console port to the network in any way,
including attaching a modem to the port. Be aware that a break on the console port might
give unauthorized individuals total control of the firewall, even with access control
configured.
3 Limit who can telnet into your router.
4 Don't enable any local service (such as SNMP or NTP) that you don't use. Any enabled
service could present a potential security risk. A determined hacker might be able to find
creative ways to misuse the enabled services to access the firewall or the network.
5 For local services that are enabled, protect against misuse. Protect by configuring the
services to communicate only with specific peers, and protect by configuring rules to
block packets for the services at specific interfaces.
6 Protect against IP spoofing by making sure the firewall is active.
7 Keep the firewall in a secured (locked) room.
14.7 Packet Filtering Vs Firewall
Below are some comparisons between the ZyAIR’s filtering and firewall functions.