Target Skills:
Ability to set up Client Access Controls. |
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Controlling Client Access
One important security setting is how to control client access to the various
messaging services on the server. Netscape Messaging Server controls
client access through a process commonly called "TCP Wrappers", which are
filters that run at the TCP/IP level for each service (SMTP, IMAP4, and
POP3).
Allow and Deny Filters
For each service, separate sets of Allow filters and Deny filters control
access. Allow filters explicitly grant access; Deny filters explicitly
forbid access.
The very simplest form of a filter is
service: hostSpec
where service is the name of the service (such as smtp, pop, or imap) and
hostSpec is the host name, IP address, or wildcard name or pattern that
represents the client requesting access. Here are two examples:
imap: roberts.newyork.airius.com
pop: ALL
If these are Allow filters, the first one grants the host roberts.newyork.airius.com
access to the IMAP service, and the second one grants all clients access
to the POP service. If they are Deny filters, they deny those clients access
to those services.
You will try these filters out in the exercise on the following pages.
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