Services 
 
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7.2  Firewall 
7.2.1  ALG 
Application Layer Gateway (ALG) is a software component that manages specific application 
protocols such as Session Initiation Protocol (SIP) and File Transfer Protocol (FTP). The ALG acts as 
an intermediary between the internet and an application server and allows or denies traffic of 
certain types to the application server. It does this by intercepting and analyzing the specified 
traffic, allocating resources, and defining dynamic policies to allow traffic to pass through. 
To access the configuration page, log in to the web UI of the ONT and choose Service > Firewall > 
Dynamic DNS. 
 
Parameter description 
The File Transfer Protocol (FTP) is a standard network protocol used for the transfer of 
computer files between a client and server on a computer network. 
The users on LAN can share resources on the FTP server on WAN only when it is selected. 
The Trivial File Transfer Protocol (TFTP) is a simple file transfer protocol that allows a client to 
get a file from or put a file onto a remote host. 
H.323 is a recommendation from the ITU Telecommunication Standardization Sector (ITU-T) 
that defines the protocols to provide audio-visual communication sessions on any packet 
network. The H.323 standard addresses call signaling and control, multimedia transport and 
control, and bandwidth control for point-to-point and multi-point conferences. 
The IP phone and network conference function can be used on the computers connected to 
the ONT only when this function is enabled. 
The Real Time Streaming Protocol (RTSP) is a network control protocol designed for use in 
entertainment and communications systems to control streaming media servers. The 
protocol is used for establishing and controlling media sessions between end points. 
The users on LAN can view videos on demand when this function is enabled.