ARRIS 2247-N8-10NA (v9.1.x) Admin Handbook - Manual (Page 50)

Administrator’s Handbook
50
set ip ntp alt-server-address alt_server_address
Specify the NTP server(s) to use for time updates. The NTP server-address and alt-server-address can be
entered as DNS names as well as IP addresses.
set ip ntp update-period minutes
update-period specifies how often, in minutes, the gateway should update the clock. Default is 60 .
Application Layer Gateway (ALG) commands
These commands allow you to enable or disable the router’s support for a variety of Application Layer Gate-
ways (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 proto-
col-specific 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 deciding 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 .