March, 1990 This is the source code for a POP3 server running under 4.3BSD. This server was written at the University of California at Davis. The server implements the minimal POP3 command list, plus two extension commands. You can get a copy of this distribution with anonymous FTP at: ftp.ucadavis.edu:/pub/pop3d.tar POP3, the Post Office Protocol (version 3), is described in RFC1225. A copy of RFC1225 is included with this distribution. At UC Davis, POP is used to deliver mail to microcomputers using a 4.3BSD system as a mail gateway. This is an addition to the normal model of using the 4.3BSD system as the mailbox and letting the microcomputer merely read the mail from there. If you ever look at the source code, you may see that this server supports two extra commands, "HOST", to allow clients to specify hostnames for gateway service, and "MBOX" to allow clients to specify an alternate mailbox file. Be assured that you can ignore these extra commands, since the server is completely upwards compatible and standard POP3 client programs will not use this command. If you discover bugs or problems with this software, please feel free to contact me. Katie Stevens Information Technology -- Campus Access Point University of California Davis, CA 95616 (916)752-3426 dkstevens@ucdavis.edu
Last update: 05/03/94 The following things have been changed for the Debian distribution: - changed the makefile (install target) - changed the definitions for the mail and pop directories in pop3.h - wrote a manpage for pop3d (from the catpage) Peter Tobias <tobias@et-inf.fho-emden.de>
Installation Instructions for POP3 server (08-19-91)
=========================================
General:
The POP3 server is a TCP/IP server. It accepts one line commands,
and responds with one or more ASCII text lines. For a complete
description of the POP3 syntax, please refer to RFC 1225.
The POP3 server is similar to the FTP and SMTP servers; it should
be installed like ftpd and smtpd.
UNIX installation:
-----------------
- copy and compile the pop3d program
- copy the pop3d program to the /etc directory; it should
be owned by root and should have permissions 700
once installed, its directory listing should look something like this:
-rwx------ 1 root 30720 Aug 10 1990 /etc/pop3d
- add an entry for pop3d in the file /etc/services
it should look like this:
pop3 110/tcp postoffice
- add an entry for pop3d in the file /etc/inetd.conf
it should look like this:
pop3 stream tcp nowait root /etc/pop3d pop3d
- restart the inetd program; inetd will connect incoming TCP/IP
traffic for the POP3 server to the pop3d program. Get the PID
number for inetd with the ps command; then restart inetd:
aggie: 9> ps -fax | grep inetd
92 ? I 3:19 /etc/inetd
14470 p0 S 0:00 grep inetd
aggie: 10> kill -HUP 92
aggie: 11>
- pop3d is now installed
Sun OS installation:
-------------------
- copy and compile the pop3d program
- copy the pop3d program to the /etc directory (NOTE: network
files may be stored in a different directory on your system); it should
be owned by root and should have permissions 700
once installed, its directory listing should look something like this:
-rwx------ 1 root 49152 Feb 8 1990 /etc/in.pop3d
- if you use an /etc/services file, add an entry for pop3d in the
file /etc/services it should look like this:
pop3 110/tcp postoffice
- add an entry for pop3d in the file /usr/etc/inetd.conf
it should look like this:
pop3 stream tcp nowait root /etc/in.pop3d in.pop3d
- if you are running Yellow Pages, remake yp
- restart the inetd program; inetd will connect incoming TCP/IP
traffic for the POP3 server to the pop3d program. Get the PID
number for inetd with the ps command; then restart inetd:
wilma% ps -ax | grep inetd
114 ? IW 0:15 inetd
2082 p1 S 0:00 grep inetd
wilma% kill -HUP 114
wilma%
- pop3d is now installed
Special note for various UNIX-like operating systems
====================================================
When you compile the server, you may get an error involving
the flock() function or the LOCK_EX and LOCK_UN
constants. The purpose of these calls is to create an exclusive
lock on the mailbox file. This prevents other processes from
re-writing the mailbox while the POP server is also writing or
reading from the mailbox.
In general, the flock() function may not be avialable on your system.
The 'brute force' way to get around this problem is to simply
comment out the flock() calls. However, this will leave the mailbox
file unprotected from other processes; if two processes write to the
file at the same time, the results are undefined.
As an alternative, you should check the source code for other
e-mail prcoesses on your system. Presumably, they will have some
kind of file locking mechanism. Modify the POP3 server source
code to use the same file locking mechanism.
-----------------------------------------------------------------------------
-- Katie Stevens
dkstevens@ucdavis.edu
Information Technology -- Campus Access Point
University of California, Davis
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