ultrix man page for qmail-popup

qmail-popup(8)                                                System Manager's Manual                                               qmail-popup(8)

NAME
       qmail-popup - read a POP username and password

SYNOPSIS
       qmail-popup hostname subprogram

DESCRIPTION
       qmail-popup reads a POP username and password from the network.  It then runs subprogram.

       qmail-popup is most commonly invoked from inetd as

          qmail-popup CHANGEME checkpassword qmail-pop3d Maildir

       with CHANGEME replaced by the fully qualified domain name of the local host.

       qmail-popup  expects descriptor 0 to read from the network and descriptor 1 to write to the network.  It reads a username and password from
       descriptor 0 in POP's USER-PASS style or APOP style.  It invokes subprogram, with the same descriptors 0 and 1; descriptor 2 writing to the
       network;  and  descriptor  3  reading  the username, a 0 byte, the password, another 0 byte, an APOP timestamp derived from hostname, and a
       final 0 byte.  qmail-popup then waits for subprogram to finish.  It prints an error message if subprogram crashes or exits nonzero.

       qmail-popup should be used only within a secure network.  Otherwise an eavesdropper can steal passwords.  Even if you use APOP,  an  active
       attacker can still take over the connection and wreak havoc.

       qmail-popup has a 20-minute idle timeout.

       qmail-popup is based on a program contributed by Russ Nelson.

SEE ALSO
       maildir(5), qmail-local(8), qmail-pop3d(8)

                                                                                                                                    qmail-popup(8)