Re: [fw-wiz] CERT vulnerability note VU# 539363 (fwd)

From: Mikael Olsson (mikael.olssonat_private)
Date: Wed Oct 16 2002 - 14:15:52 PDT

  • Next message: Mikael Olsson: "Re: [fw-wiz] Proverbial appliance vs software based firewall"

    Paul Robertson wrote:
    > 
    > Hmmm, is this because "normal" rules aren't optimized or hashed, but state
    > tables were kind of pre-assumed to be a performance issue, and therefore
    > given performance attention at the design stage?  Maybe it's just because
    > the state information is easy to do a boolean comparison on?
    
    I'll concede that maybe our rule lookups could be faster.
    Heck, not even maybe, they _could_ be faster, given enough head 
    scratching and cool algorithm design.
    
    It's just that it sort of feels iffy to me.  The ruleset is the ultimate
    policy enforcement point.  I'm personally not altogether comfortable 
    with changing this from an easily verifiable linear lookup with straight-
    forward comparisons to some n-dimensional single-hop constant-time lookup 
    that you need a master's degree in math and a minor in CS to understand.
    
    This is not to say that it hasn't been done.  There was this company that
    shall remain nameless that sold cool blue boxes with blitzingly fast 
    rule lookups and no statefulness.  Today, they tout header compression.
    
    
    > Have any kind of feel for where the line is?  Daniel's 5000 to 100 mention
    > has me wondering if we can codify the sorts of places where this can be an
    > easy performance win for folks who are in high utilization scenerios.
    
    Ugh. If it was just a line, I might be able to give you an estimate.
    Unfortunately, it's more like a 3D function surface of state creation
    rate, ruleset size, and raw throughput.
    Not to mention product specifics.
    
    It is however an interesting question.  I think I'll coherce the QA 
    people into cranking out some more diagrams when I'm done abusing 
    them with all the testing for the current release :)
    
    For our software on current hardware, I think something along the line
    of "tens of thousands of connections per second" coupled with "the first 
    handful of rules" would be where statelessness might pay off, but I 
    don't think that's anywhere near useful as general advice.
    
    
    > Why can't I log stateless rules?  
    
    Answered in another subthread.
    
    > [1] We had a dearth of gameshow sounds in this thread ;)
    
    *meEEep*
    
    
    -- 
    Mikael Olsson, Clavister AB
    Storgatan 12, Box 393, SE-891 28 ÖRNSKÖLDSVIK, Sweden
    Phone: +46 (0)660 29 92 00   Mobile: +46 (0)70 26 222 05
    Fax: +46 (0)660 122 50       WWW: http://www.clavister.com
    _______________________________________________
    firewall-wizards mailing list
    firewall-wizardsat_private
    http://honor.icsalabs.com/mailman/listinfo/firewall-wizards
    



    This archive was generated by hypermail 2b30 : Wed Oct 16 2002 - 14:44:34 PDT