ZyWALL ATP Series User’s Guide
346
C
HAPTER
14
ALG
14.1 ALG Overview
Application Layer Gateway (ALG) allows the following applications to operate properly through the
Zyxel Device’s NAT.
• SIP - Session Initiation Protocol (SIP) - An application-layer protocol that can be used to create voice
and multimedia sessions over Internet.
• H.323 - A teleconferencing protocol suite that provides audio, data and video conferencing.
• FTP - File Transfer Protocol - an Internet file transfer service.
The following example shows SIP signaling (
1
) and audio (
2
) sessions between SIP clients
A
and
B
and the
SIP server.
Figure 236
SIP ALG Example
The ALG feature is only needed for traffic that goes through the Zyxel Device’s NAT.
14.1.1 What You Need to Know
Application Layer Gateway (ALG), NAT and Security Policy
The Zyxel Device can function as an Application Layer Gateway (ALG) to allow certain NAT un-friendly
applications (such as SIP) to operate properly through the Zyxel Device’s NAT and security policy. The
Zyxel Device dynamically creates an implicit NAT session and security policy session for the application’s
traffic from the WAN to the LAN. The ALG on the Zyxel Device supports all of the Zyxel Device’s NAT
mapping types.
Содержание ATP200
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Страница 113: ...113 PART II Technical Reference ...
Страница 216: ...Chapter 9 Interfaces ZyWALL ATP Series User s Guide 216 Configuration Network Interface Ethernet Edit External Type ...
Страница 218: ...Chapter 9 Interfaces ZyWALL ATP Series User s Guide 218 Figure 170 Configuration Network Interface Ethernet Edit OPT ...
Страница 236: ...Chapter 9 Interfaces ZyWALL ATP Series User s Guide 236 Figure 179 Configuration Network Interface PPP Add ...
Страница 244: ...Chapter 9 Interfaces ZyWALL ATP Series User s Guide 244 Figure 181 Configuration Network Interface Cellular Add Edit ...
Страница 259: ...Chapter 9 Interfaces ZyWALL ATP Series User s Guide 259 Figure 191 Configuration Network Interface VLAN Add Edit ...
Страница 260: ...Chapter 9 Interfaces ZyWALL ATP Series User s Guide 260 ...
Страница 273: ...Chapter 9 Interfaces ZyWALL ATP Series User s Guide 273 Figure 193 Configuration Network Interface Bridge Add Edit ...
Страница 361: ...Chapter 15 UPnP ZyWALL ATP Series User s Guide 361 Figure 250 Network Connections My Network Places Properties Example ...
Страница 387: ...Chapter 20 IPSec VPN ZyWALL ATP Series User s Guide 387 Figure 271 Configuration VPN IPSec VPN VPN Connection Add Edit ...
Страница 395: ...Chapter 20 IPSec VPN ZyWALL ATP Series User s Guide 395 Figure 273 Configuration VPN IPSec VPN VPN Gateway Add Edit ...
Страница 478: ...Chapter 25 Security Policy ZyWALL ATP Series User s Guide 478 Figure 328 Configuration Security Policy Policy Control ...
Страница 712: ...Chapter 37 System ZyWALL ATP Series User s Guide 712 Figure 470 Configuration System WWW Login Page Desktop View ...