Operation Manual

Access Protection and Security Mechanisms
NT/MPRI – 3 Configuration and Operation of the NT/MPRI: The Basics 50
cate charge information, you should select a charge profile for estimat-
ing charges. Then the charges incurred are estimated based on connec-
tion time. This estimate is compared with the configured limit.
New charge profiles can be created and added using the “Special /
Charge Profiles” command.
To re-enable outgoing connections after a global or call destination lim-
it has been reached, increase the configured limit.
Access Protection and Security Mechanisms
The NT/MPRI provides a multi-stage security concept which reliably
prevents unauthorized access to the local network.
The security functions can be configured at various levels:
l globally for the entire router (CLI number check, global IP filters)
l individually for specific call destinations (authentication, destina-
tion-specific IP filters, IP masquerading/NAT)
Comprehensive information about global and destination-specific IP
filters is presented in the section “IP Filters (Firewall)” on page 53.
The various functions and concepts are presented below along with
tips for configuration.
CLI Number Check
To protect the network against unauthorized access, the NT/MPRI of-
fers the option of checking the CLI number (transmitted on the D chan-
nel) against the list of numbers authorized to dial in.
To use this feature, select the menu command “Configuration / Securi-
ty / CLI Number Check” and set the option at the line “Activate CLI
Number Check” to “Yes”. Then enter for each call destination the CLI
number transmitted on the D channel. If CLI numbers already were de-
fined during configuration of the call destinations, these numbers are
listed here.
If a remote router has a B channel pool and dials in from various num-
bers, you must enter all the CLI numbers of the pool.
The CLI number of each incoming call is checked against the numbers
defined in the CLI number database. If the number is listed the incom-
ing call is provisionally accepted, subject to further security mecha-
nisms.
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