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Application Level Gateway (ALG) Configurations
Here you can enable or disable ALGs. Some protocols and applications require special
handling of the IP payload to make them work with network address translation (NAT). Each
ALG provides special handling for a specific protocol or application. A number of ALGs for
common applications are enabled by default.
PPTP
Allows multiple machines on the LAN to connect to their corporate network using PPTP
protocol.
IPSec VPN
Allows multiple VPN clients to connect to their corporate network using IPSec. Some VPN
clients support traversal of IPSec through NAT. This ALG may interfere with the operation of
such VPN clients. If you are having trouble connecting with your corporate network, try turning
this ALG off.
Please check with the system adminstrator of your corporate network whether your VPN client
supports NAT traversal.
RTSP
Allows applications that use Real Time Streaming Protocol to receive streaming media from the
internet. QuickTime and Real Player are some of the common applications using this protocol.
Windows Messenger
Supports use of Microsoft Windows Messenger (the Internet messaging client that ships with
Microsoft Windows) on LAN computers. The SIP ALG must also be enabled when the
Windows Messenger ALG is enabled.
FTP
Allows FTP clients and servers to transfer data across NAT. Refer to the
Advanced -> Virtual Server
page if you want to host an FTP server.
NetMeeting
Allows Microsoft NetMeeting clients to communicate across NAT. Note that if you want your
buddies to call you, you should also set up a virtual server for NetMeeting. Refer to the
Advanced -> Virtual Server
page for information on how to set up a virtual server.
SIP
Allows devices and applications using VoIP (Voice over IP) to communicate across NAT. Some
VoIP applications and devices have the ability to discover NAT devices and work around them.
This ALG may interfere with the operation of such devices. If you are having trouble making
VoIP calls, try turning this ALG off.
Wake-On-LAN
This feature enables forwarding of "magic packets" (that is, specially formatted wake-up
packets) from the WAN to a LAN computer or other device that is "Wake on LAN" (WOL)
capable. The WOL device must be defined as such on the
Advanced -> Virtual Server
page.
The LAN IP address for the virtual server is typically set to the broadcast address
