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Printable Version: RFC2196.PDF
RFC 2196 Site Security Handbook September 1997 4.5.4.7 Make Your Modem Programming as "Bullet-proof" as Possible Be sure modems can't be reprogrammed while they're in service. At a minimum, make sure that three plus signs won't put your dial-in modems into command mode! Program your modems to reset to your standard configuration at the start of each new call. Failing this, make them reset at the end of each call. This precaution will protect you against accidental reprogramming of your modems. Resetting at both the end and the beginning of each call will assure an even higher level of confidence that a new caller will not inherit a previous caller's session. Check that your modems terminate calls cleanly. When a user logs out from an access server, verify that the server hangs up the phone line properly. It is equally important that the server forces logouts from whatever sessions were active if the user hangs up unexpectedly. 4.6 Auditing This section covers the procedures for collecting data generated by network activity, which may be useful in analyzing the security of a network and responding to security incidents. 4.6.1 What to Collect Audit data should include any attempt to achieve a different security level by any person, process, or other entity in the network. This includes login and logout, super user access (or the non-UNIX equivalent), ticket generation (for Kerberos, for example), and any other change of access or status. It is especially important to note "anonymous" or "guest" access to public servers. The actual data to collect will differ for different sites and for different types of access changes within a site. In general, the information you want to collect includes: username and hostname, for login and logout; previous and new access rights, for a change of access rights; and a timestamp. Of course, there is much more information which might be gathered, depending on what the system makes available and how much space is available to store that information. One very important note: do not gather passwords. This creates an enormous potential security breach if the audit records should be improperly accessed. Do not gather incorrect passwords either, as they often differ from valid passwords by only a single character or transposition. Fraser, Ed. Informational [Page 34]