![background image](http://html1.mh-extra.com/html/zyxel-communications/unified-security-gateway-zywall-300/unified-security-gateway-zywall-300_user-manual_943725439.webp)
Chapter 21 ALG
ZyWALL USG 300 User’s Guide
439
21.3 ALG Technical Reference
Here is more detailed information about the Application Layer Gateway.
ALG
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 examines and uses IP address and port number information embedded in
the VoIP traffic’s data stream. When a device behind the ZyWALL uses an
application for which the ZyWALL has VoIP pass through enabled, the ZyWALL
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.
ALG and Trunks
If you send your ALG-managed traffic through an interface trunk and all of the
interfaces are set to active, you can configure routing policies to specify which
interface the ALG-managed traffic uses.
You could also have a trunk with one interface set to active and a second interface
set to passive. The ZyWALL does not automatically change ALG-managed
Enable FTP ALG
Turn on the FTP ALG to detect FTP (File Transfer Program) traffic and
help build FTP sessions through the ZyWALL’s NAT. Enabling the FTP
ALG also allows you to use the application patrol to detect FTP traffic
and manage the FTP traffic’s bandwidth (see
Enable FTP
Transformations
Select this option to have the ZyWALL modify IP addresses and port
numbers embedded in the FTP data payload to match the ZyWALL’s
NAT environment.
Clear this option if you have an FTP device or server that will modify IP
addresses and port numbers embedded in the FTP data payload to
match the ZyWALL’s NAT environment.
FTP Signaling
Port
If you are using a custom TCP port number (not 21) for FTP traffic,
enter it here.
Additional FTP
Signaling Port
for
Transformations
If you are also using FTP on an additional TCP port number, enter it
here.
Apply
Click
Apply
to
save your changes back to the ZyWALL.
Reset
Click
Reset
to return the screen to its last-saved settings.
Table 111
Configuration > Network > ALG (continued)
LABEL
DESCRIPTION
Summary of Contents for Unified Security Gateway ZyWALL 300
Page 2: ......
Page 30: ...Table of Contents ZyWALL USG 300 User s Guide 30 ...
Page 31: ...31 PART I User s Guide ...
Page 32: ...32 ...
Page 38: ...Chapter 1 Introducing the ZyWALL ZyWALL USG 300 User s Guide 38 ...
Page 46: ...Chapter 2 Features and Applications ZyWALL USG 300 User s Guide 46 ...
Page 64: ...Chapter 3 Web Configurator ZyWALL USG 300 User s Guide 64 ...
Page 74: ...Chapter 4 Installation Setup Wizard ZyWALL USG 300 User s Guide 74 ...
Page 116: ...Chapter 6 Configuration Basics ZyWALL USG 300 User s Guide 116 ...
Page 184: ...Chapter 7 Tutorials ZyWALL USG 300 User s Guide 184 ...
Page 221: ...221 PART II Technical Reference ...
Page 222: ...222 ...
Page 288: ...Chapter 11 Registration ZyWALL USG 300 User s Guide 288 ...
Page 378: ...Chapter 14 Trunks ZyWALL USG 300 User s Guide 378 ...
Page 394: ...Chapter 15 Policy and Static Routes ZyWALL USG 300 User s Guide 394 ...
Page 408: ...Chapter 16 Routing Protocols ZyWALL USG 300 User s Guide 408 ...
Page 428: ...Chapter 19 NAT ZyWALL USG 300 User s Guide 428 ...
Page 454: ...Chapter 23 Authentication Policy ZyWALL USG 300 User s Guide 454 ...
Page 472: ...Chapter 24 Firewall ZyWALL USG 300 User s Guide 472 ...
Page 534: ...Chapter 27 SSL User Screens ZyWALL USG 300 User s Guide 534 ...
Page 536: ...Chapter 28 SSL User Application Screens ZyWALL USG 300 User s Guide 536 ...
Page 544: ...Chapter 29 SSL User File Sharing ZyWALL USG 300 User s Guide 544 ...
Page 638: ...Chapter 35 ADP ZyWALL USG 300 User s Guide 638 Figure 448 Profiles Protocol Anomaly ...
Page 682: ...Chapter 37 Content Filter Reports ZyWALL USG 300 User s Guide 682 ...
Page 700: ...Chapter 38 Anti Spam ZyWALL USG 300 User s Guide 700 ...
Page 722: ...Chapter 39 Device HA ZyWALL USG 300 User s Guide 722 ...
Page 738: ...Chapter 40 User Group ZyWALL USG 300 User s Guide 738 ...
Page 744: ...Chapter 41 Addresses ZyWALL USG 300 User s Guide 744 ...
Page 756: ...Chapter 43 Schedules ZyWALL USG 300 User s Guide 756 ...
Page 772: ...Chapter 45 Authentication Method ZyWALL USG 300 User s Guide 772 ...
Page 794: ...Chapter 46 Certificates ZyWALL USG 300 User s Guide 794 ...
Page 806: ...Chapter 48 SSL Application ZyWALL USG 300 User s Guide 806 ...
Page 811: ...Chapter 49 Endpoint Security ZyWALL USG 300 User s Guide 811 ...
Page 866: ...Chapter 50 System ZyWALL USG 300 User s Guide 866 ...
Page 873: ...Chapter 51 Log and Report ZyWALL USG 300 User s Guide 873 ...
Page 886: ...Chapter 51 Log and Report ZyWALL USG 300 User s Guide 886 ...
Page 916: ...Chapter 54 Packet Flow Explore ZyWALL USG 300 User s Guide 916 ...
Page 918: ...Chapter 55 Reboot ZyWALL USG 300 User s Guide 918 ...
Page 920: ...Chapter 56 Shutdown ZyWALL USG 300 User s Guide 920 ...
Page 948: ...Chapter 58 Product Specifications ZyWALL USG 300 User s Guide 948 ...
Page 1014: ...Appendix A Log Descriptions ZyWALL USG 300 User s Guide 1014 ...
Page 1124: ...Appendix F Open Software Announcements ZyWALL USG 300 User s Guide 1124 ...