Application Layer Gateway (Alg) Commands; Dynamic Dns Commands - Motorola NVG510 Administrator's Handbook

Administrator's Handbook

Application Layer Gateway (ALG) commands

These commands allow you to enable or disable the router's support for a variety of Application Layer Gateways
(ALGs). An application layer gateway (ALG) is a NAT component that helps certain application sessions to pass
cleanly through NAT. Each ALG has a slightly different function based on the particular application's protocol-spe-
cific requirements.
An internal client first establishes a connection with the ALG. The ALG determines if the connection should be
allowed or not and then establishes a connection with the destination computer. All communications go through
two connections – client to ALG and ALG to destination. The ALG monitors all traffic against its rules before decid-
ing whether or not to forward it. The ALG is the only address seen by the public Internet so the internal network is
concealed. In some situations, it may be desirable to disable some of the ALGs.
set ip alg esp-enable [ on | off ]
Turns the ESP (Encapsulated Security Payload) ALG for file transfers on or off. Default is on.
set ip alg esp-setup-timeout value
Specifies the timeout value for the ESP ALG setup. Default is 180.
set ip alg esp-stream-timeout value
Specifies the timeout value for the ESP ALG streaming. Default is 300.
set ip alg ftp-enable [ on | off ]
Turns the FTP (File Transfer Protocol) ALG for file transfers on or off. Default is on.
set ip alg h323-enable [ on | off ]
Turns the H323 ALG for audio, video, and data communications across IP-based networks on or off. Default is
on.
set ip alg pptp-enable [ on | off ]
Turns the PPTP (Point-to-Point Transfer Protocol) ALG for authentication on or off. Default is on.
set ip alg sip-enable [ on | off ]
Turns the SIP (Session Initiation Protocol) ALG for voice communication initiation on or off. Default is on.
set ip alg tftp-enable [ on | off ]
Turns the TFTP (Trivial File Transfer Protocol) ALG for simple file transfers and firmware updates on or off.
Default is on.

Dynamic DNS Commands

set ip dynamic-dns enable [ off | on ]
Enables or disables Dynamic DNS. Dynamic DNS support allows you to use the free services of www.dyndns.org.
Dynamic DNS automatically directs any public Internet request for your computer's name to your current dynami-
cally-assigned IP address. This allows you to get to the IP address assigned to your Gateway, even though your
actual IP address may change as a result of a PPPoE connection to the Internet.
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