ZyWALL / USG (ZLD) CLI Reference Guide
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ALG
This chapter covers how to use the ZyWALL / USG’s ALG feature to allow certain applications to
pass through the ZyWALL / USG.
21.1 ALG Introduction
The ZyWALL / USG can function as an Application Layer Gateway (ALG) to allow certain NAT un-
friendly applications (such as SIP) to operate properly through the ZyWALL / USG’s NAT.
Some applications cannot operate through NAT (are NAT un-friendly) because they embed IP
addresses and port numbers in their packets’ data payload. The ZyWALL / USG examines and uses
IP address and port number information embedded in the VoIP traffic’s data stream. When a device
behind the ZyWALL / USG uses an application for which the ZyWALL / USG has VoIP pass through
enabled, the ZyWALL / USG translates the device’s private IP address inside the data stream to a
public IP address. It also records session port numbers and allows the related sessions to go
through the firewall so the application’s traffic can come in from the WAN to the LAN.
The ZyWALL / USG only needs to use the ALG feature for traffic that goes through the ZyWALL /
USG’s NAT. The firewall allows related sessions for VoIP applications that register with a server. The
firewall allows or blocks peer to peer VoIP traffic based on the firewall rules.
You do not need to use a TURN (Traversal Using Relay NAT) server for VoIP devices behind the
ZyWALL / USG when you enable the SIP ALG.
Содержание ZyWALL USG Series
Страница 19: ...19 PART I Introduction ...
Страница 20: ...20 ...
Страница 38: ...Chapter 2 User and Privilege Modes ZyWALL USG ZLD CLI Reference Guide 38 ...
Страница 39: ...39 PART II Reference ...
Страница 40: ...40 ...
Страница 48: ...Chapter 4 Status ZyWALL USG ZLD CLI Reference Guide 48 ...
Страница 52: ...Chapter 5 Registration ZyWALL USG ZLD CLI Reference Guide 52 ...
Страница 128: ...Chapter 15 Route ZyWALL USG ZLD CLI Reference Guide 128 ...
Страница 136: ...Chapter 17 Zones ZyWALL USG ZLD CLI Reference Guide 136 ...
Страница 140: ...Chapter 18 DDNS ZyWALL USG ZLD CLI Reference Guide 140 ...
Страница 148: ...Chapter 20 HTTP Redirect ZyWALL USG ZLD CLI Reference Guide 148 ...
Страница 152: ...Chapter 21 ALG ZyWALL USG ZLD CLI Reference Guide 152 ...
Страница 156: ...Chapter 22 UPnP ZyWALL USG ZLD CLI Reference Guide 156 ...
Страница 159: ...Chapter 23 IP MAC Binding ZyWALL USG ZLD CLI Reference Guide 159 ...
Страница 178: ...Chapter 25 Secure Policy ZyWALL USG ZLD CLI Reference Guide 178 ...
Страница 218: ...Chapter 32 Application Patrol ZyWALL USG ZLD CLI Reference Guide 218 ...
Страница 236: ...Chapter 34 IDP Commands ZyWALL USG ZLD CLI Reference Guide 236 ...
Страница 246: ...Chapter 35 Content Filtering ZyWALL USG ZLD CLI Reference Guide 246 ...
Страница 256: ...Chapter 36 Anti Spam ZyWALL USG ZLD CLI Reference Guide 256 ...
Страница 262: ...Chapter 37 SSL Inspection ZyWALL USG ZLD CLI Reference Guide 262 ...
Страница 268: ...Chapter 38 Device HA ZyWALL USG ZLD CLI Reference Guide 268 ...
Страница 284: ...Chapter 41 Addresses ZyWALL USG ZLD CLI Reference Guide 284 ...
Страница 288: ...Chapter 42 Services ZyWALL USG ZLD CLI Reference Guide 288 ...
Страница 302: ...Chapter 46 Authentication Server ZyWALL USG ZLD CLI Reference Guide 302 ...
Страница 338: ...Chapter 52 System Remote Management ZyWALL USG ZLD CLI Reference Guide 338 ...
Страница 358: ...Chapter 53 File Manager ZyWALL USG ZLD CLI Reference Guide 358 ...
Страница 372: ...Chapter 56 Session Timeout ZyWALL USG ZLD CLI Reference Guide 372 ...
Страница 374: ...Chapter 57 Diagnostics ZyWALL USG ZLD CLI Reference Guide 374 ...
Страница 384: ...Chapter 59 Maintenance Tools ZyWALL USG ZLD CLI Reference Guide 384 ...
Страница 426: ...List of Commands Alphabetical ZyWALL USG ZLD CLI Reference Guide 426 ...