.TH qmail-popup 8

.SH NAME

qmail-popup \- read a POP username and password

.SH SYNOPSIS

.B qmail-popup

.I hostname

.I subprogram

.SH DESCRIPTION

.B qmail-popup

reads a POP username and password from the network.

It then runs

.IR subprogram .

.B qmail-popup

is most commonly invoked from

.B inetd

as

.EX

   qmail-popup CHANGEME checkpassword qmail-pop3d Maildir

.EE

with

CHANGEME

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

.B 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

.IR 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

.IR hostname ,

and a final 0 byte.

.B qmail-popup

then waits for

.I subprogram

to finish.

It prints an error message if

.I subprogram

crashes or exits nonzero.

.B 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.

.B qmail-popup

has a 20-minute idle timeout.

.B qmail-popup

is based on a program contributed by Russ Nelson.

.SH "SEE ALSO"

maildir(5),

qmail-local(8),

qmail-pop3d(8)