Справочник Пользователя для Dynalink RTA1025W

Скачать
Страница из 159
ADSL Router User Manual 
 
96 
NAT ALG Configuration   
The need for IP address translation arises when a network's internal IP addresses 
cannot be used outside the network either for security reasons or because they are 
invalid for use outside the network. Use of NAT (Network Address Translation) 
devices allows local hosts on such private networks to transparently access the 
external global Internet and enables access to selective local hosts from the outside. 
ALG (Application Level Gateway) is a security component that augments a firewall or 
NAT employed in a computer network. ALG allows legitimate application data to pass 
through the security checks of the firewall that would have otherwise restricted the 
traffic for not meeting its filter criteria. ALG application specific translation agents 
allow an application on a host in one address realm to connect to its counterpart 
running on a host in different realm transparently. An ALG may interact with NAT to 
set up state, use NAT state information, modify application specific payload and 
perform whatever else is necessary to get the application running across disparate 
address realms.   
Enable VPN ALG: 
 
VPN ALG allows two or more 
simultaneous VPN connections 
through this router. The default setting 
for VPN ALG is enabled. 
Enable SIP ALG:   
SIP ALG allows two or more 
simultaneous VoIP phone calls made 
by VoIP clients through this router. The
default setting for SIP ALG is enabled.
Transparent use of SIP-based devices in a 
NAT scenario requires that modifications 
be made to the SIP messages. These 
modifications are performed by the ALG.   
SIP ALG provides functionality to allow 
VoIP traffic to pass both from the private to 
public and public to private side of the 
firewall when using Network Address 
Translation (NAT). The SIP-ALG inspects 
and modifies SIP traffic to allow SIP traffic 
to pass through the firewall so that 
person-to-person SIP sessions may be 
established. 
Click Apply to upload your setting.