popa3d(8) [debian man page]
POPA3D(8) System Administration POPA3D(8) NAME
popa3d - Post Office Protocol (POP3) server SYNOPSIS
popa3d [-D] [-V] DESCRIPTION
popa3d is a Post Office Protocol version 3 (POP3) server. A POP3 server operates on local mailboxes on behalf of its remote users. Users can connect at any time to check their mailbox and fetch the mail that has accumulated. The advantage of this "pull" approach is that any user with a simple POP3-capable mail reader program can receive mail, eschewing the need for a full-fledged Mail Transfer Agent (MTA) and a permanent network connection. Note that POP3 can only be used to retrieve mail, not to send it. To send mail, the SMTP protocol is commonly used. For access to a mailbox through POP3, the username must be in the password database. Additionally, popa3d does not permit null passwords and will refuse to serve mail for root (UID 0) users. OPTIONS
-D Standalone server mode. In this mode, popa3d will become a daemon, accepting connections on the pop3 port (110/tcp) and forking child processes to handle them. This has lower overhead than starting popa3d from an inetd equivalent (which popa3d assumes by default) and is thus useful on busy servers to reduce load. In this mode popa3d also does quite a few checks to significantly reduce the impact of connection flood attacks. -V Print version information and exit. COMMANDS
A normal POP3 session progresses through three states: AUTHORIZATION, TRANSACTION, and UPDATE. After the TCP connection opens, the client must authenticate itself to the server during the AUTHORIZATION state. The following commands are supported in the AUTHORIZATION state (all command names are case-insensitive). USER name Authenticate as user name. PASS string Authenticate using password string. QUIT Quit; do not enter UPDATE state. When authorization is successful, the server enters the TRANSACTION state. The client can now list and retrieve messages or mark messages for deletion. The following commands are supported in the TRANSACTION state. DELE msg Mark message for deletion. LAST Show highest message number accessed (obsolete). LIST [msg] List message number and size. NOOP Do nothing. QUIT Quit; enter UPDATE state. RETR msg Retrieve message. RSET Clear deletion marks. STAT Return total number of messages and total size. TOP msg n Show top n lines of message body. UIDL [msg] List message number and digest. When the client issues the QUIT command in the TRANSACTION state, the server enters the UPDATE state. All messages that were marked for deletion are now removed. The server then closes the connection. BUGS
POP3 transmits passwords in plaintext and thus, if you care about the security of your individual user accounts, should only be used either in trusted networks or tunneled over encrypted channels. There exist extensions to the protocol that are supposed to fix this problem. popa3d does not support them yet, partly because this isn't going to fully fix the problem. In fact, APOP and the weaker defined SASL mechanisms such as CRAM-MD5 may potentially be even less secure than transmission of plaintext passwords because of the requirement that plaintext equivalents be stored on the server. AUTHORS
Solar Designer <solar at openwall.com> This manual page is based heavily on the one Camiel Dobbelaar wrote for OpenBSD. SEE ALSO
Official Internet Protocol Standard STD 53, also known as RFC 1939. http://www.openwall.com/popa3d/ Openwall Project 2 March 2003 POPA3D(8)
Check Out this Related Man Page
Net::POP3(3pm) Perl Programmers Reference Guide Net::POP3(3pm) NAME
Net::POP3 - Post Office Protocol 3 Client class (RFC1939) SYNOPSIS
use Net::POP3; # Constructors $pop = Net::POP3->new('pop3host'); $pop = Net::POP3->new('pop3host', Timeout => 60); if ($pop->login($username, $password) > 0) { my $msgnums = $pop->list; # hashref of msgnum => size foreach my $msgnum (keys %$msgnums) { my $msg = $pop->get($msgnum); print @$msg; $pop->delete($msgnum); } } $pop->quit; DESCRIPTION
This module implements a client interface to the POP3 protocol, enabling a perl5 application to talk to POP3 servers. This documentation assumes that you are familiar with the POP3 protocol described in RFC1939. A new Net::POP3 object must be created with the new method. Once this has been done, all POP3 commands are accessed via method calls on the object. CONSTRUCTOR
new ( [ HOST ] [, OPTIONS ] 0 This is the constructor for a new Net::POP3 object. "HOST" is the name of the remote host to which an POP3 connection is required. "HOST" is optional. If "HOST" is not given then it may instead be passed as the "Host" option described below. If neither is given then the "POP3_Hosts" specified in "Net::Config" will be used. "OPTIONS" are passed in a hash like fashion, using key and value pairs. Possible options are: Host - POP3 host to connect to. It may be a single scalar, as defined for the "PeerAddr" option in IO::Socket::INET, or a reference to an array with hosts to try in turn. The "host" method will return the value which was used to connect to the host. ResvPort - If given then the socket for the "Net::POP3" object will be bound to the local port given using "bind" when the socket is created. Timeout - Maximum time, in seconds, to wait for a response from the POP3 server (default: 120) Debug - Enable debugging information METHODS
Unless otherwise stated all methods return either a true or false value, with true meaning that the operation was a success. When a method states that it returns a value, failure will be returned as undef or an empty list. auth ( USERNAME, PASSWORD ) Attempt SASL authentication. user ( USER ) Send the USER command. pass ( PASS ) Send the PASS command. Returns the number of messages in the mailbox. login ( [ USER [, PASS ]] ) Send both the USER and PASS commands. If "PASS" is not given the "Net::POP3" uses "Net::Netrc" to lookup the password using the host and username. If the username is not specified then the current user name will be used. Returns the number of messages in the mailbox. However if there are no messages on the server the string "0E0" will be returned. This is will give a true value in a boolean context, but zero in a numeric context. If there was an error authenticating the user then undef will be returned. apop ( [ USER [, PASS ]] ) Authenticate with the server identifying as "USER" with password "PASS". Similar to "login", but the password is not sent in clear text. To use this method you must have the Digest::MD5 or the MD5 module installed, otherwise this method will return undef. banner () Return the sever's connection banner capa () Return a reference to a hash of the capabilities of the server. APOP is added as a pseudo capability. Note that I've been unable to find a list of the standard capability values, and some appear to be multi-word and some are not. We make an attempt at intelligently parsing them, but it may not be correct. capabilities () Just like capa, but only uses a cache from the last time we asked the server, so as to avoid asking more than once. top ( MSGNUM [, NUMLINES ] ) Get the header and the first "NUMLINES" of the body for the message "MSGNUM". Returns a reference to an array which contains the lines of text read from the server. list ( [ MSGNUM ] ) If called with an argument the "list" returns the size of the message in octets. If called without arguments a reference to a hash is returned. The keys will be the "MSGNUM"'s of all undeleted messages and the values will be their size in octets. get ( MSGNUM [, FH ] ) Get the message "MSGNUM" from the remote mailbox. If "FH" is not given then get returns a reference to an array which contains the lines of text read from the server. If "FH" is given then the lines returned from the server are printed to the filehandle "FH". getfh ( MSGNUM ) As per get(), but returns a tied filehandle. Reading from this filehandle returns the requested message. The filehandle will return EOF at the end of the message and should not be reused. last () Returns the highest "MSGNUM" of all the messages accessed. popstat () Returns a list of two elements. These are the number of undeleted elements and the size of the mbox in octets. ping ( USER ) Returns a list of two elements. These are the number of new messages and the total number of messages for "USER". uidl ( [ MSGNUM ] ) Returns a unique identifier for "MSGNUM" if given. If "MSGNUM" is not given "uidl" returns a reference to a hash where the keys are the message numbers and the values are the unique identifiers. delete ( MSGNUM ) Mark message "MSGNUM" to be deleted from the remote mailbox. All messages that are marked to be deleted will be removed from the remote mailbox when the server connection closed. reset () Reset the status of the remote POP3 server. This includes resetting the status of all messages to not be deleted. quit () Quit and close the connection to the remote POP3 server. Any messages marked as deleted will be deleted from the remote mailbox. NOTES
If a "Net::POP3" object goes out of scope before "quit" method is called then the "reset" method will called before the connection is closed. This means that any messages marked to be deleted will not be. SEE ALSO
Net::Netrc, Net::Cmd AUTHOR
Graham Barr <gbarr@pobox.com> COPYRIGHT
Copyright (c) 1995-2003 Graham Barr. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. perl v5.18.2 2014-01-06 Net::POP3(3pm)