Chapter 11 Network Address Translation (NAT)
VMG1312-B Series User’s Guide
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11.3.1 Add New Application
This screen let s you creat e new NAT applicat ion rules. Click Add n e w a pplica t ion in the
Applica t ions screen to open t he following scr een.
Figure 76 Applicat ions: Add
The following t able describes t he labels in t his screen.
11.4 The Port Triggering Screen
Som e ser vices use a dedicated range of port s on the client side and a dedicated range of ports on
the server side. Wit h regular port forwarding you set a forwarding port in NAT t o forward a service
( com ing in from t he server on the WAN) to t he I P address of a com puter on t he client side (LAN) .
The problem is that port forwarding only forwards a service to a single LAN I P address. I n order t o
use t he sam e service on a different LAN com puter, you have to m anually replace the LAN
com puter's I P address in the forwarding port with another LAN com put er's I P address.
Trigger port forwarding solves this problem by allowing com puters on t he LAN t o dynam ically take
turns using t he service. The Device records t he I P addr ess of a LAN com put er that sends traffic to
the WAN t o request a service wit h a specific por t num ber and protocol ( a "t rigger" port) . When t he
Device's WAN port receives a r esponse with a specific port num ber and prot ocol ( "open" port ) , t he
Device forwards t he t raffic to the LAN I P address of t he com puter that sent the request . Aft er t hat
com puter ’s connect ion for that service closes, anot her com put er on t he LAN can use t he service in
the sam e m anner. This way you do not need t o configure a new I P address each tim e you want a
different LAN com put er t o use the application.
Table 54 Applications: Add
LABEL DESCRIPTION
WAN I nt erface Select t he WAN int erface that you w ant t o apply this NAT rule to.
Server I P
Address
Enter the inside I P address of t he application here.
Application
Category
Select t he category of t he application from the drop- down list box.
Application
For w arded
Select a service from the dr op- down list box and the Device aut om atically configures t he
protocol, st art, end, and m ap port num ber t hat define t he ser vice.
View Rule Click t his to display t he configuration of the serv ice that you have chosen in Applicat ion
Fow a r ded.
OK Click OK t o save your changes.
Cancel Click Ca ncel to exit t his screen without saving.
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