Provided by: qmail_1.06-4_amd64 bug


       qmail-popup - read a POP username and password


       qmail-popup hostname subprogram


       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.


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