Install and set the SENDMAIL mail server

Article Title: Install and set the SENDMAIL mail server. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.

Sendmail is often a "Forbidden Zone" for general system administrators, because most system users have high requirements and dependencies on E-Mail, it can be said that the system manager should be prepared to accept the protests and complaints like snow! The "internal mail" of Sendmail seems to be a bit difficult to understand: the sendmail related to the settings. cf files, if not for a long time, read it as if reading tianshu, only know that it contains English text and numbers! So the average person can always do nothing, as long as they can use it. However, unfortunately, sendmail, which comes with the machine, always has an astonishing "additional function 」, there are often bugs or backdoors that can make boring people intrude into the path. Some bugs also allow the intruder to get the highest root permission through Sendmail! Once the root permission is taken away, the machine can be slaughtered at will, which is the worst and may damage the system!

Sun is widely used in China, and I am a little familiar with Sun. However, Sun's Sendmail is not flattering. It can be said that as long as Sun's Sendmail is still in use and there is no "regular" patch, there is no need to talk about system security, it is also a white talk. If Sun's Sendmail is still in use, it may be detonated if the system is holding an indefinite time bomb and does not pay attention to it at any time :(. In this regard, you can refer to CERT or 8lgm for a look. Almost as long as there is a sendmail problem, Sun mostly runs ..... Don't laugh at Sendmail from other systems. Although the attendance rate is not as high as Sun, it is also a problem. On the other hand, Sendmail 8.6.9 and earlier versions have just released an ident Bug. If this is convenient, you must change to the latest version. If it is inconvenient
In v8.6.5 and later versions, there is a way to remedy the issue, that is, add such a line to sendmail. cf:

Orident = 0

Indicates that no ident check is performed.
Before v8.6.5, you must replace it with the latest version.

This software has the highest rating in terms of system security. Currently, all known bugs have been modified. The main reason is, of course, thanks to Eric Allman, WHO (or they) when a major Bug (such as system installation) is detected, a new version is immediately released. This software is a public domain, and its source code can be found on various ftp servers on the network. The developer of the Software Automates some necessary setup steps. Therefore, installing the software is not as difficult as you think. If the compile time is reached, the installation will be completed in less than half an hour!

3.1 download the latest Sendmail version

The latest Sendmail version can be obtained from the ftp://ftp.sendmail.org/pub/sendmail!
For example, sendmail.8.9.3.tar.gz is the latest version released as of the end of the article. size: 1068290 byte

For release of the latest version, browse the Sendmail home http://www.sendmail.org

3.2 install Sendmail

Remove the tar.gz package from tar fvxz sendmail.8.9.3.tar.gz and use make-f to compile the package.

After compilation, the system will generate a system setting file, that is, sendmail. cf (this file is usually stored in/etc)

Next, follow these steps to continue the installation: (Note :~ /Sendmail is the unlocked sendmail directory)

1. Switch to the config file directory ~ Under/sendmail/cf. Find an appropriate XXXX. mc file for your system. I generally use tcpproto. mc

This file does not use uucp. If you use the tcpproto. mc file, I tried it in solaris 2.3. Remember to add a line in the file:

OSTYPE (solaris2)

Sun 4.1.3. In the directory ~ There are several ostype () files available under/sendmail/cf/OSTYPE,

OSTYPE () is only available in this directory (). Also, if it is system V's/bin/mail, it seems that you have to add OSTYPE ().

For more information, see DOCUMENT :~ /Sendmail/cf/README. I hope some experienced friends can add :)

What if I accidentally forget to add OSTYPE? There will be an "unknow mailer error" error, and the message will not be received.

One thing to remind everyone is: In ~ The. mc files of various systems seen by/sendmail/cf are all the authors of Sendmail 8.6.x.

Eric Allman's "Demo" is shown to you. Therefore, we can see that there is a "cs" in all the file names. If these files are not modified, then errors will occur. There are a lot of changes to be made, so, for example, the lazy person, using tcpproto. mc is still relatively simple and will not make mistakes :)