E-Mail; Nat - DETEWE OpenCom 130 Mounting And Commissioning Manual

It is possible to call up Web
■
pages simultaneously from sev-
eral workstations.
The OpenCom 130 can block ac-
■
cess to certain Web pages by
means of filter lists.

E-mail

One of the most important services
in the Internet is e-mail. E-mails are
buffered in individual e-mail ac-
counts on a mail server. Mail servers
are operated by ISPs for example.
With the OpenCom 130 you can set
up one or more e-mail accounts for
every user account configured on
the OpenCom 130. These e-mail
accounts are then checked at regular
intervals.
If there are new e-mails in an e-mail
account, and the OpenCom 130 has
been configured for this function,
the user specified in the
OpenCom 130 user account is noti-
fied of the new e-mail on his system
terminal. System telephones from
the OpenPhone 6x and 2x product
range can also display information
such as the sender or the subject of
the e-mail.
Configuration Examples

NAT

Network address translation (NAT) is
activated on accessing the Internet
(ISP). You require this feature in or-
der to translate internal IP addresses
to valid external IP addresses. This
has three important consequences
for Internet access:
Several workstations can share a
■
single Internet access. You do
not require a LAN access, only a
single account with the Internet
service provider.
The IP addresses used in the LAN
■
are translated into IP addresses
valid worldwide. So you require
no such addresses for your LAN.
Only TCP/IP connections trig-
■
gered from a workstation can be
established. Consequently, while
you can call up Web pages from
a workstation, you cannot install
a Web server visible in the Inter-
net on a workstation.
Certain protocols cannot be used
when NAT is being used. This affects
protocols with the following proper-
ties:
TCP/IP addresses are trans-
■
ported in the useful load, e.g.
NetBIOS over TCP/IP.
The protocol requires an active,
■
inward-directed connection es-
tablishment, e.g. ICQ.
Useful Information on Internet Access
73