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
maildir(5), qmail-local(8), qmail-pop3d(8)
Man(1) output converted with