Chapter Six: Security | Incoming data calls 83 |
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Incoming data calls
By default, the DIVA LAN ISDN Modem refuses all incoming ISDN data calls. This effectively shuts the door on unauthorized systems
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
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 |
1 | IP address: static |
Remote IP address: static | |
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Assigned | to |
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Remote Computer
IP address: dynamic
Remote IP address: dynamic
2 | IP address: static | |
Remote IP address: dynamic | ||
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3 | IP address: static | |
| Remote IP address: static | |
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4 | IP address: dynamic | |
Remote IP address: dynamic | ||
| IP address: static | |
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5 | ||
Remote IP address: dynamic | ||
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6 | IP address: dynamic | |
Remote IP address: dynamic | ||
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7 | IP address: dynamic | |
Remote IP address: dynamic | ||
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No assignments
Addresses must match
Assigned to
Fails
Fails
Fails
IP address: static
Remote IP address: dynamic
IP address: static
Remote IP address: static
IP address: static
Remote IP address: static
IP address: dynamic
Remote IP address: dynamic
IP address: static
Remote IP address: dynamic
IP address: dynamic
Remote IP address: dynamic
