Hello List/Mark,
I am looking at ways to extend UW-IMAP soas to be able to support very large numbers of users on a Linux system. The problem arises from the standard limit of UIDs being <= 65535 on Linux systems without re-compiling the kernel and "taking your chances". There are two issues involved, assuming you have a large number of users:
1. Being able to put more than 65k on one machine
2. Being able to put arbitrary users on arbitrary machines where the UIDs of your users in your DB can be well over 65k.
We already have one solution that solves #2 partially by mapping our real global UIDs to local ones for Linux's use on the servers in question; we are looking at other possible solutions that cover both #1 and #2 while still using UW-IMAPd.
One idea that I have is to:
1. use pam_mysql for authentication
2. put all the email for all user in 1 nice hashed directory tree that is owned by a SINGLE user
3. modify UW-IMAP to construct the location of a user's subtree within the global tree from the user login (i.e. query mysql).
4. modify UW-IMAP to now allow any access to any files outside the user's subtree.
5. Add any additional code to UW-IMAP so that the users do not have to be in the /etc/passwd file -- all user-specific info is read from mysql.
The result, if this is doable in a way that is not very intrusive to UW-IMAP, would be the ability to have any number of users on a machine because they would all be virtual [no real linux users].
Has something like this been done? Are there any serious concerns to be aware of in this type of scenario? What are the main hooks that one should look at for perusing this type of patch?
Delivery of email to "virtual" users in a scenario like this is completely doable and we already have a solution for that. Sending authenicated outbound email is very doable. It is only the UW-IMAPd/POP3d component that seems tricky.
Thank you, -Erik Kangas
PS - While certain other IMAP servers that shall remain nameless do handle this particular user virtualization issue innately, there are certain reasons why we like and want to stick with UW-IMAP. These are mostly requirements such as:
* Easy integration of the email store with sendmail/procmail
* Fast shared access to email folders (i.e. mbx for indexed formats)
* SSL support
* Complete and solid and well tested IMAP v4.1 support
* Built-in full support for: SEARCH and SORT commands.
--
Erik Kangas, Ph.D. --- President of Lux Scientiae, Incorporated
Lux Scientiae: 1-800-441-6612 P.O. Box 326 FAX: 1-413-332-0598 Westwood, Massachusetts Cell: 1-617-596-9558 02090, USA AIM Chat: Screen Name "luxsci"
[EMAIL PROTECTED] --- http://luxsci.com
