1 .TH qmail-popup 8

     2 .SH NAME

     3 qmail-popup \- read a POP username and password

     4 .SH SYNOPSIS

     5 .B qmail-popup

     6 .I hostname

     7 .I subprogram

     8 .SH DESCRIPTION

     9 .B qmail-popup

    10 reads a POP username and password from the network.

    11 It then runs

    12 .IR subprogram .

    13 

    14 .B qmail-popup

    15 is most commonly invoked from

    16 .B inetd

    17 as

    18 

    19 .EX

    20    qmail-popup CHANGEME checkpassword qmail-pop3d Maildir

    21 .EE

    22 

    23 with

    24 CHANGEME

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

    26 

    27 .B qmail-popup

    28 expects descriptor 0 to read from the network

    29 and descriptor 1 to write to the network.

    30 It reads a username and password from descriptor 0

    31 in POP's USER-PASS style or APOP style.

    32 It invokes

    33 .IR subprogram ,

    34 with the same descriptors 0 and 1;

    35 descriptor 2 writing to the network;

    36 and descriptor 3 reading the username, a 0 byte, the password,

    37 another 0 byte, 

    38 an APOP timestamp derived from

    39 .IR hostname ,

    40 and a final 0 byte.

    41 .B qmail-popup

    42 then waits for

    43 .I subprogram

    44 to finish.

    45 It prints an error message if

    46 .I subprogram

    47 crashes or exits nonzero.

    48 

    49 .B qmail-popup

    50 should be used only within

    51 a secure network.

    52 Otherwise an eavesdropper can steal passwords.

    53 Even if you use APOP,

    54 an active attacker can still take over the connection

    55 and wreak havoc.

    56 

    57 .B qmail-popup

    58 has a 20-minute idle timeout.

    59 

    60 .B qmail-popup

    61 is based on a program contributed by Russ Nelson.

    62 .SH "SEE ALSO"

    63 maildir(5),

    64 qmail-local(8),

    65 qmail-pop3d(8)