Alg - ZyXEL Communications VMG Series User Manual

Figure 168 Network Setting > NAT > DMZ
The following table describes the fields in this screen.
Table 90 Network Setting > NAT > DMZ
LABEL
Default Server
Address
Apply
Cancel

13.5 ALG

Application Layer Gateway (ALG) allows customized NAT traversal filters to support address and port
translation for certain applications such as File Transfer Protocol (FTP), Session Initiation Protocol (SIP), or
file transfer in Instant Messaging (IM) applications. It allows SIP calls to pass through the Zyxel Device.
When the Zyxel Device registers with the SIP register server, the SIP ALG translates the Zyxel Device's
private IP address inside the SIP data stream to a public IP address. You do not need to use STUN or an
outbound proxy if your Zyxel Device is behind a SIP ALG.
Click Network Setting > NAT > ALG to open the ALG screen. Use this screen to enable and disable the
NAT Application Layer Gateway (ALG) in the Zyxel Device.
Application Layer Gateway (ALG) allows certain applications such as File Transfer Protocol (FTP), Session
Initiation Protocol (SIP), or file transfer in Instant Messaging (IM) applications to pass through the Zyxel
Device.
Chapter 13 Network Address Translation (NAT)
DESCRIPTION
Enter the IP address of the default server which receives packets from ports that are not
specified in the Port Forwarding screen.
Note: If you do not assign a default server, the Zyxel Device discards all packets
received for ports not specified in the virtual server configuration.
Click this to save your changes back to the Zyxel Device.
Click Cancel to restore your previously saved settings.
VMG/EMG/AM/DM/GM Series User's Guide
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