Port Trigger Screen - ZyXEL Communications ARMOR G1 User Manual

The following table describes the labels in this screen.
Table 27 Settings > Internet > Passthrough
LABEL
ALG Setup
FTP
H.323
SIP
SNMP
RTSP
IRC
VPN Passthrough
PPTP
L2TP
IPSEC
Apply
Cancel

9.7 Port Trigger Screen

Some services use a dedicated range of ports on the client side and a dedicated range of ports on the
server side. With regular port forwarding, you set a forwarding port in NAT to forward a service (coming
in from the server on the WAN) to the IP address of a computer on the client side (LAN). The problem is
that port forwarding only forwards a service to a single LAN IP address. In order to use the same service
on a different LAN computer, you have to manually replace the LAN computer's IP address in the
forwarding port with another LAN computer's IP address.
Trigger port forwarding addresses this problem. Trigger port forwarding allows computers on the LAN to
dynamically take turns using the service. The Zyxel Device records the IP address of a LAN computer that
sends traffic to the WAN to request a service with a specific port number and protocol (a "trigger" port).
When the Zyxel Device's WAN port receives a response with a specific port number and protocol
("open" port), the Zyxel Device forwards the traffic to the LAN IP address of the computer that sent the
request. After that computer's connection for that service closes, another computer on the LAN can use
the service in the same manner. This way you do not need to configure a new IP address each time you
want a different LAN computer to use the application.
Chapter 9 WAN
DESCRIPTION
Select Enable to allow TCP packets with a specified port destination to pass through.
Select Enable to allow peer-to-peer H.323 calls.
Select Enable to make sure SIP (VoIP) works correctly with port-forwarding and address-
mapping rules.
Select Enable to allow a manager station to manage and monitor the NBG6818 through the
network via SNMP.
Select Enable to have the NBG6818 detect RTSP traffic and help build RTSP sessions through
its NAT.
Select Enable to allow clients to have real-time communications with others on the Internet.
Select Enable to allow VPN clients to make outbound PPTP connections. It is required in order
to connect to a PPTP VPN account. If PPTP is disabled, then when a client sends a request to
a VPN server, the server will reply to the NBG6818 and the NBG6818 will drop the request.
When PPTP is enabled, the NBG6818 will forward the reply from the VPN server to the client
that initiated the request, and the connection will establish successfully.
Select Enable to allow VPN clients to make outbound L2TP connections. It is required in order
to connect to a L2TP VPN account. If L2TP is disabled, then when a client sends a request to a
VPN server, the server will reply to the NBG6818 and the NBG6818 will drop the request. When
L2TP is enabled, the NBG6818 will forward the reply from the VPN server to the client that
initiated the request, and the connection will establish successfully.
Select Enable to allow VPN clients to make outbound IPSec connections. It is required in
order to connect to a IPSec VPN account. If IPSEC is disabled, then when a client sends a
request to a VPN server, the server will reply to the NBG6818 and the NBG6818 will drop the
request. When IPSEC is enabled, the NBG6818 will forward the reply from the VPN server to
the client that initiated the request, and the connection will establish successfully.
Click Apply to save your changes back to the NBG6818.
Click Cancel to begin configuring this screen afresh.
NBG6818 User's Guide
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