Incoming data calls – Eicon Networks DIVA LAN ISDN User Manual

Page 83

Chapter Six: Security

Incoming data calls

Incoming data calls

By default, the DIVA LAN ISDN Modem refuses all incoming ISDN data calls. This effectively shuts the door
on unauthorized systems dialing-in. (Voice calls are not blocked by this setting.)

When support for incoming data calls is activated and an incoming call is received, the DIVA LAN ISDN
Modem compares the user name and password supplied by the remote site against the remote user name and
remote password configured for each connection profile. If a match is found, the call is accepted. Otherwise,
the call is rejected. Therefore, to accept incoming data calls you must define call authentication settings for the
appropriate profile (as explained in the steps below).

Note

Since the DIVA LAN ISDN Modem checks the ISP profile first, if both profiles have the same remote user

name, the incoming call will always connect with the ISP profile.

Incoming data calls can only be received if there is an available B-channel. To keep a free channel, you must
use PPP (or V.120) for your existing connection. If you are using MLPPP, you will only be able to receive
incoming voice calls if no data call is active. See “Choose a connection protocol” on page 20 for more
information.

Note

When you enable callback support (page 88) using the web configuration interface, the DIVA LAN ISDN

Modem automatically enables support for incoming data calls.

Incoming calls and IP addressing

For an incoming call to successfully connect, you must define a proper IP addressing scheme for the profile
that will handle the connection. This means setting the following three parameters: IP address, Subnet mask,
and Remote IP address.

Generally, when you configure the DIVA LAN ISDN Modem to connect to the Internet, you set the IP address
parameter to 0.0.0.0, which means that the address will be dynamically assigned by the ISP when the profile
connects. When you receive an incoming call however, it may be the responsibility of the DIVA LAN ISDN
Modem to assign an IP address to the caller. In this case, the static address you set for Remote IP address
would be adopted by the caller.

The following diagram illustrates the effects of potential addressing schemes. (The subnet mask is omitted
from this discussion, but should be set to match the IP address. See“About IP addresses” on page 120 for more
information on masks.)

DIVA LAN ISDN Modem

Remote Computer

No assignments

Fails

IP address:
Remote IP address:

static

IP address:
Remote IP address: dynamic

static

IP address: dynamic
Remote IP address: dynamic

IP address:
Remote IP address:

static

IP address:
Remote IP address: dynamic

static

Assigned to

Addresses must match

IP address: dynamic
Remote IP address: dynamic

IP address: static
Remote IP address: dynamic

IP address: dynamic
Remote IP address: dynamic

IP address:
Remote IP address:

static

IP address:
Remote IP address:

static

IP address:
Remote IP address: dynamic

static