Sun Java System Messaging Server 6.3 Administration Guide Client User-Name Specification

For client host machines that support the identd service as described in RFC 1413, you can further identify the specific client requesting service by including the client’s user name in the clientSpec entry in a filter. In that case the entry has the form:


where user is the user name as returned by the client’s identd service (or a wildcard name).

Specifying client user names in a filter can be useful, but keep these caveats in mind:

The user-name lookup capability can in some cases help you guard against attack from unauthorized users on the client’s host. It is possible in some TCP/IP implementations, for example, for intruders to use rsh (remote shell service) to impersonate trusted client hosts. If the client host supports the ident service, you can use user-name lookups to detect such attacks.