Telindus 1031, User And Reference Manual

Page: 134 / 394

Telindus 1031 Router Chapter 7
User manual Configuring the router
124
7.4.7 Configuring NAT
Despite the workarounds offered by the previous two PAT configuration attributes to overcome the lim-
itations of PAT, there are situations where PAT is inadequate. For example, it is not possible to have
several web servers on your local network. It is also impossible to run an application with fixed source
port numbers on several local devices that are connected simultaneously to a single Internet device. This
can only be solved by using several official IP addresses: Network Address Translation.
Use the following to configure NAT:
• Use the addresses attribute to enter all the official IP addresses that have to be used for Network
Address Translation. Refer to telindus1031/router/defaultNat/addresses on page 216 .
• Use the gateway attribute to define the gateway addresses from routes on which NAT or PAT should
be applied. Refer to telindus1031/router/defaultNat/gateway on page 216 .
Important remark - using NAT on the LAN interface
Consider the following configuration:
• telindus1031/lanInterface/ip/address = 172.31.74.1
• telindus1031/router/defaultNat/addresses
=
{ officialAddress = 172.31.74.1; privateAddress = <opt> }
•
telindus1031/wanInterface/ppp/ip/address
=
2.2.2.2
The above means that NAT is used on the LAN interface and the router uses the address 172.31.74.1
as official IP address.
The problem that arises here is that the router can no longer be managed via the LAN interface using
the management tool (TMA, Telnet, etc.). This because the NAT route has priority over the LAN route
and, because it is a NAT address, the router does not accept incoming traffic on the address
172.31.74.1.
The solution is to add the WAN IP address to the
addresses
table as private address:
telindus1031/router/addresses = { officialAddress
=
172.31.74.1; privateAddress
=
2.2.2.2 }
. In that case, the manage-
ment tool “service” runs on the WAN IP address. This means however, that the WAN has to be up.