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Printable Version: RFC2196.PDF
RFC 2196 Site Security Handbook September 1997 IP address spoofing, packet sniffing, etc. Users and site management must appreciate the risks involved. If you decide to provide walk-up connections, plan the service carefully and define precisely where you will provide it so that you can ensure the necessary physical access security. A walk-up host should be authenticated before its user is permitted to access resources on your network. As an alternative, it may be possible to control physical access. For example, if the service is to be used by students, you might only provide walk-up connection sockets in student laboratories. If you are providing walk-up access for visitors to connect back to their home networks (e.g., to read e-mail, etc.) in your facility, consider using a separate subnet that has no connectivity to the internal network. Keep an eye on any area that contains unmonitored access to the network, such as vacant offices. It may be sensible to disconnect such areas at the wiring closet, and consider using secure hubs and monitoring attempts to connect unauthorized hosts. 4.5.3 Other Network Technologies Technologies considered here include X.25, ISDN, SMDS, DDS and Frame Relay. All are provided via physical links which go through telephone exchanges, providing the potential for them to be diverted. Crackers are certainly interested in telephone switches as well as in data networks! With switched technologies, use Permanent Virtual Circuits or Closed User Groups whenever this is possible. Technologies which provide authentication and/or encryption (such as IPv6) are evolving rapidly; consider using them on links where security is important. 4.5.4 Modems 4.5.4.1 Modem Lines Must Be Managed Although they provide convenient access to a site for its users, they can also provide an effective detour around the site's firewalls. For this reason it is essential to maintain proper control of modems. Don't allow users to install a modem line without proper authorization. This includes temporary installations (e.g., plugging a modem into a facsimile or telephone line overnight). Fraser, Ed. Informational [Page 31]