The Dmz Screen; The Alg Screen - ZyXEL Communications VMG Series User Manual

11.4 The DMZ Screen

A LAN client in the Demilitarized Zone (DMZ) is no longer behind the Zyxel Device and therefore can run
any Internet applications such as video conferencing and Internet gaming without restrictions. This,
however, poses security threats to the Zyxel Device.
Note: Use an IPv4 address for the DMZ server.
Figure 107 Network Setting > NAT > DMZ
The following table describes the fields in this screen.
Table 75 Network Setting > NAT > DMZ
LABEL
Default Server
Address
Cancel
Apply

11.5 The ALG Screen

Some NAT routers may include a SIP Application Layer Gateway (ALG). A SIP ALG allows customized
NAT traversal filters to support address and port translation for certain applications such as FTP, SIP, or file
transfer in IM applications. It allows SIP calls to pass through NAT by examining and translating IP
addresses embedded in the data stream. 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.
Use this screen to enable and disable the NAT and SIP (VoIP) ALG in the Zyxel Device. To access this
screen, click Network Setting > NAT > ALG.
Chapter 11 Network Address Translation (NAT)
DESCRIPTION
Enter the IP address of the default server which receives packets from ports that are not
specified in the NAT Port Forwarding screen.
Note: If you do not assign a Default Server Address, the Zyxel Device discards all
packets received for ports that are not specified in the NAT Port Forwarding
screen.
Click Cancel to restore your previously saved settings.
Click Apply to save your changes.
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