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AJ_2609's avatar
AJ_2609
Icon for Nimbostratus rankNimbostratus
Jan 06, 2012

Using iRule to limit POST/GET vars to prevent Hashtable collisions

Does anyone know how it would be possible to limit the number of post and get vars via an iRule so as to prevent some type of hash table collision dos?

 

 

Say setting the number of vars to 500, anything else will get logged and dropped?

 

 

 

 

 

TIA

 

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iRules
  • hoolio's avatar
    hoolio
    Icon for Cirrostratus rankCirrostratus
    Jan 06, 2012
    Hi AJ,

     

     

    Sure, here's an example iRule which should do this:

     

     

    http://devcentral.f5.com/Community/GroupDetails/tabid/1082223/aff/5/afv/topic/aft/2159136/afc/2235372/Default.aspx

     

     

    I'm not sure that you could exploit this vulnerability using the query string. But if you wanted to check the overall query string length, you could use [string length [HTTP::query]].

     

     

    Aaron