[fw-wiz] imap and content inspection?

Date: 10/09/03

  • Next message: Guido Bolognesi [ Zen ]: "Re: [fw-wiz] Help yourself get the answers"
    To: firewall-wizards@honor.icsalabs.com
    Date: Thu, 9 Oct 2003 15:41:24 +0400


    I am planning IMAP filtering proxy implementation. A quick look into rfc
    shows the IMAP protocol appears to be designed to maximize firewall
    application layer problems ;-). I mean it requires proxy to handle full
    email mime parsing, besides quite sophisticated protocol itself, thus
    making proxy very complex pile of code, comparable with IMAP server itself,
    which turns its security (through simplicity!) advantage questionable.
    And - there are numerous ways to retreive various parts of messages without
    handling message as whole; if content inspection means simple virus check
    with binary result (OK/BAD) it is not really a problem, but if we employ other
    content inspection types, it ruins the whole idea.

    I know here are many people on the list who know implementation details in
    depth, how do other vendors solve this problem? Is "best practice" now
    to just handle FETCH and UID FETCH commands syntax issued by widespread email
    clients and not to care if other techniques are used?

    p.s. for those interested in "fwtk sequel", i expect something like "public
    beta" to be finished before Samhain. ;-) i doubt i will include "real" imap4
    proxy, though :(
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