December 2002
Intermediate to advanced
1232 pages
56h 38m
English
Content preview from Sendmail, 3rd Edition
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STARTTLS
Encryption can improve the security of sendmail. Ordinarily, mail is sent between two machines in the clear. That is, if you were to watch the transmission of bytes over the network[33] you would see what is actually being sent or received. This includes passwords, which are also sent in the clear.
To reduce the likelihood that someone watching the network will find something that can harm you, you can encrypt the stream of data. Three forms of encryption are available as of this writing:
- SSL
SSL is a method for encrypting a single connection over which network traffic can flow. One implementation of SSL is available from http://www.openssl.org/.
- TLS
Transport Layer Security, defined by RFC2246, is the successor to SSL that provides further means of connection encryption. It, too, is available from http://www.openssl.org.
- SMTP AUTH=
The DIGEST-MD5 and GSSAPI mechanisms, among others, for the AUTH= extension to SMTP, also provides stream encryption.
In this section we show you:
How to install the OpenSSL library
What digital certificates and their acronyms are
How to include support for STARTTLS in sendmail
How to set up the configuration file for use with STARTTLS
Which sendmail macros are relevant to STARTTLS
The SSL Library
An SSL library might already exist on your machine. If so, and if it is a secure version, you can skip this section.
The SSL library is available from the OpenSSL organization at the following sites:
| http://www.OpenSSL.org/source/ ← web download |
| ftp://ftp.openssl.org/source/ ... |
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.