Before you begin the process of building sendmail you should consider obtaining and installing several important support packages. These packages are not needed to install sendmail, but they will make your system more convenient and safer. Typically, each takes 20 minutes to an hour to install, so you really are not facing a serious time commitment.
The packages we will discuss in this section are outlined in Table 3-1 and discussed in the sections that follow.
Support for the tcpwrappers package is still included in V8.12 sendmail, but its functionality has been replaced by the access database (Section 7.5), introduced in V8.9. The current access database has completely replaced the need for this tcpwrappers package.
With this package you can monitor and filter incoming requests for the sendmail daemon. Specifically, you can restrict the systems that can connect to sendmail by editing and adding lines to a simple access list file, typically /etc/hosts.deny.
The important components from the tcpwrappers distribution that you will need to include are the tcpd.h file and the libwrap.a library. The first is typically installed in /usr/local/include ...