Forum Discussion

Bob_10976's avatar
Bob_10976
Icon for Nimbostratus rankNimbostratus
Apr 16, 2009

iRule to Block request with Host Header

I'm needing some help with creating an iRule that will block any request that doesn't have a host header value.

 

 

For example if someone was to preform a GET / HTTP/1.1 on one our websites or even assoicated public IP address I want to block that.

 

 

Also for the record, I’m not a programmer of any type so I apologize in advance for any newbie/stupid follow up questions..

 

 

Thanks,

 

Bob
application delivery
dev
devops
iRules
  • The_Bhattman's avatar
    The_Bhattman
    Icon for Nimbostratus rankNimbostratus
    Apr 16, 2009
    There are several ways to approach this

    Here are some examples 

     
 when HTTP_REQUEST { 
   if { [HTTP::header "Host"] equals " " }  {  
       reject 
     } 
 }

    or 

     
  
 class publicaddr { 
   "215.25.25.35" 
   "215.25.25.33" 
   "215.25.25.34" 
 } 
  
  
  
 when CLIENT_ACCEPTED { 
   if { [matchclass [IP::remote_addr] equals $::publicaddr] } {  
      reject 
      } 
 }

    These are just examples.

    Hope this helps

    CB

  • Bob_10976's avatar
    Bob_10976
    Icon for Nimbostratus rankNimbostratus
    Apr 16, 2009
    Thanks for the help...

     

     

    Just before your reply we actually came up with the below rule, but I like your reject option better...

     

     

    when HTTP_REQUEST {

     

    if { ([string tolower [HTTP::host]] equals "") } {

     

    HTTP::respond 401

     

    }

     

    }

     

     

     

    Thanks,

     

    Bob
  • The_Bhattman's avatar
    The_Bhattman
    Icon for Nimbostratus rankNimbostratus
    Apr 16, 2009
    You can also use either drop or discard. This will cause the current packet or connection to be discarded, but i don't think it will send a reset. Where as reject causes the connection to be rejected, returning a reset as appropriate for the protocol.

     

     

    You can find more detail on in the wiki irule section under GLOBAL commands.

     

     

    CB