??? Newer versions of perl(1) object to PATH environment variables that begin with
a dot (suchas .:/bin:/usr/bin). V8 clears the PATH variable before executing
programs in a user??™s ~/.forward file. Some shells put it back with the dot first.
Under such versions of the Bourne shell, execute perl(1) scripts like this:
|"PATH=/bin:/usr/bin /home/usr/bin/script.pl"
??? There is no check in the T command to determine that the names listed are the
names of real users. That is, if you mistakenly entered Tuupc when you really
meant Tuucp, pre-V8 sendmail remained silent and UUCP mail mysteriously
failed. V8.7 and above sendmail log warning messages.
This is the Title of the Book, eMatter Edition
Copyright ?© 2007 O??™Reilly & Associates, Inc. All rights reserved.
183
Chapter 5 CHAPTER 5
Authentication and Encryption
In this chapter, we cover two ways to protect your email server and the mail it
handles:*
??? SMTP AUTH prevents untrusted machines from using your mail server to send
undesirable mail. It also enables client sendmail machines to authenticate themselves
to a server for outbound relaying.
??? Public/Private Key Cryptography provides the underpinnings used by STARTTLS.
STARTTLS encrypts email content to prevent it from being snooped.
5.1 Support SMTP AUTH
Support for the SMTP extension AUTH, as defined by RFC2554, was first included in
sendmail beginning with V8.
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