ZyXEL Communications VMG1312-B Series, User Manual

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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 t he
Applica t ion s screen t o open t he following screen.
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 services use a dedicat ed range of port s on t he client side and a dedicat ed range of port s on
t he 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 t he WAN) t o t he I P address of a com put er on t he client side ( LAN) .
The problem is t hat port forwarding only forwards a service t o a single LAN I P address. I n order t o
use t he sam e service on a different LAN com put er, you have t o m anually replace t he LAN
com put er's I P address in t he forwarding port wit h anot her LAN com put er's I P address.
Trigger port forwarding solves t his problem by allowing com put ers on t he LAN t o dynam ically t ake
t urns using t he service. The Device records t he I P address of a LAN com put er t hat sends t raffic t o
t he WAN t o request a service wit h a specific port num ber and prot ocol ( a " t rigger" port ) . When t he
Device's WAN port receives a response wit h a specific port num ber and prot ocol ( " open" port ) , t he
Device forwards t he t raffic t o t he LAN I P address of t he com put er t hat sent t he request . Aft er t hat
com put er ’s connect ion for t hat service closes, anot her com put er on t he LAN can use t he service in
t he sam e m anner. This way you do not need t o configure a new I P address each t im e you want a
different LAN com put er t o use t he applicat ion.
Table 54 Applicat ions: Add
LABEL DESCRIPTION
WAN I nt erface Select t he WAN int erface t hat you want t o apply t his NAT rule t o.
Server I P
Address Ent er t he inside I P address of t he applicat ion here.
Applicat ion
Cat egory Select t he cat egory of t he applicat ion from t he dr op- dow n list box.
Applicat ion
Forwarded Select a service from t he drop- dow n list box and t he Device aut om at ically configures t he
prot ocol, st art , end, and m ap port num ber t hat define t he service.
View Rule Click t his t o display t he configurat ion of t he service t hat you have chosen in Applica t ion
Fow a r de d .
OK Click OK t o save your changes.
Cancel Click Ca n ce l t o exit t his scr een w it hout saving.