Linux Server Security, Second Edition

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

Postfix

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After configuring the chroot jail and editing master.cf, all you need to do is start Post-

fix the way you normally would:

postfix start.

Postfix Aliases, Revealed

You probably don’t want your users connecting to and storing mail on a publicly

accessible server. The greater the separation between public servers and private serv-

ers, the better. (Don’t forget, POP3 passwords are transmitted in cleartext by default.)

Therefore, your SMTP relay should be configured to forward incoming mail to some

other server or servers on your internal network.

As alluded to in the quick-and-dirty procedure, aliases are useful for mapping email

addresses for users who don’t actually have accounts on the SMTP gateway. This

practice has two main benefits: first, most users tend to prefer meaningful email

names and short host-domain names—e.g., [e-mail] rather than

[e-mail].

Still another use of aliases is the maintenance of mailing lists. If an alias points to a

comma-separated list of addresses rather than a single address, mail sent to that alias

will be copied and sent to all specified addresses—i.e., to the mailing list.

The addresses that a mailing list comprises can also be stored in a separate file (each

address on its own line). To specify an entry