Re: [fw-wiz] Evolution of Firewalls

From: Marcus J. Ranum (mjr_at_ranum.com)
Date: 03/18/04

  • Next message: Josh Welch: "RE: [fw-wiz] Cisco PiX 501 running 6.2 - Defying me for no reason" 
    To: ark@eltex.net
Date: Thu, 18 Mar 2004 09:34:44 -0500

    ArkanoiD wrote:
    >Slightly OT, anyone aware of WHICH protocol subset do email clients
    >use when doing IMAP4? I am still planning to implement a proxy, and RFC
    >requires all servers to support the whole fscking pile of s**t!
    >(still tring to imagine that terrible brain damage that may lead
    >protocol designers to such an idiotic requirement)

    I haven't looked at it, so I can't help you there. But the "methodology"
    (it doesn't deserve the term...) I used to use is pretty straightforward.
    I'd write the main loop that handles the I/O on the command stream
    and then I'd put it inline with a couple of clients and implement the
    command set that the client used and stop when I had it working with
    a couple of clients. ;)

    This worked surprisingly well, because I was able to "minimize"
    everything as I worked on it - whenever a command came through
    I'd ask myself "what the heck?" and figure out what it was supposed
    to do and then add whatever controls I could. Look for: buffer
    lengths, pathnames, execution commands, file operations,
    password lengths, username lengths, extra tokens on commands,
    line breaks, metacharacters where appropriate, etc. Then when
    you fire up a new client you'll periodically get something new that
    makes the proxy get upset - that's how you know it's working. :)

    Ignore the RFCs. Remember: they're part of the problem, not a
    definition of the solution. I'd go so far as to say that a proxy is
    *inherently* a violation of the RFCs - if it's done right. ;)

    mjr.

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  • Next message: Josh Welch: "RE: [fw-wiz] Cisco PiX 501 running 6.2 - Defying me for no reason"

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