Technical White Paper

Dial-UP Out of Band Network Management Over PSTN


When in-band network management paths are unable to provide network administrators with the necessary means to manage remote network hardware, a dial-up out-of-band management strategy is a valuable addition to the arsenal of any network administrator who has elements distributed across wide area networks.

Implementation of out-of-band management allows a network administrator to have full control over all the elements in the wide area network, even when in-band and IP based management strategies fail. Console servers with internal dial-up modems provide a comprehensive strategy for out-of-band management. This can be a powerful tool in the arsenal of any administrator who desires a robust remote management strategy. The following are some specific considerations to note when selecting a console server for connection via dial-up over the public PSTN.

Security Considerations For Modem-Based Out Of Band Management

Allowing a serial console server to be accessed through a modem connection over the public PSTN presents some important security considerations. Many console servers include integrated modems for dial-up management connections. Third party authentication protocols (Radius, LDAP) can be implemented through the console server to ensure authentication of any dial-up user. A full featured console server will also incorporate dial-back security features and audit trail logging of all dial-up connections. Invalid attempt lock-down with notification is another useful feature to help ensure the dial-up connection remains secure. Local authentication can also be incorporated in the serial console server for dial-up authentication during network outages which may affect the in-band ability to authenticate users.

Modem Availability For Dial-Up Out Of Band Management

Another important consideration when choosing a remote console server with an internal modem is the level of availability for in-bound connections. A full featured console server will have multiple means of ensuring the internal modem is available for incoming management sessions. Modem availability features should include watch dog timers and periodic modem initialization.

Summary

An appropriate serial console server used for dial-up connections to remote sites should include several in-band and out-of-band security authentication methods. The availability of the modem is paramount, so multiple modem reset and initialization schemes must be employed by the console server firmware to ensure modem availabity. Audit trail and logging are helpful for administrators who grant dial-up access to multiple management groups.

 

About WTI

WTI is a California based company which designs and manufactures serial console servers and power control units. WTI has over 20 years experience in the out-of-band management market. WTI units are deployed in wide area networks in several industry sectors and serve multiple out-of-band management approaches. WTI is committed to the continual technological evolution of out-of-band management tools to help the network administrator save time and increase visibility and control of the proliferating number of elements in the modern data center.




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