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yang_128295's avatar
yang_128295
Historic F5 Account
Sep 20, 2005

DNS(UDP) hostname filter

Hi

 

 

bigip load balance caching DNS servers in ISP.

 

I made an irule which block DNS query packets which has pre-defined URL list.

 

(eg. bigip block DNS query which ask IP address of "www.naver.com")

 

but it didn't work.

 

please advice.

 

 

my irule is below.

 

 

 

=================

 

when CLIENT_DATA {

 

if { matchclass [UDP::payload] contains $::dnslist } {

 

log local0. "bad URL!"

 

drop

 

} else {

 

pool dns_pool

 

}

 

}

 

 

 

 

class dnslist {

 

"www.naver.com"

 

"www.yahoo.co.kr"

 

}

 

=========================
application delivery
dev
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  • krelm_52303's avatar
    krelm_52303
    Icon for Nimbostratus rankNimbostratus
    Feb 25, 2009
    I have a similar requirement - need to do DNS proxying on an LTM. I want to list internal domains (around 20 of them) in a class and send to internal DNS pool. All other requests to ISP DNS pool.

     

    Running 9.4.6 - would something like this work now?

     

     

    when DNS_REQUEST {

     

    if { ([DNS::rrtype] eq "A") and (matchclass [DNS::rrname] eq $::dnsinternal)

     

    pool internal_dns

     

    } else {

     

    pool ISP_dns

     

    }

     

    }

     

     

    class dnsinternal {

     

    "www.internal.com"

     

    "internal.com"

     

    "internal.net"

     

    }
  • krelm_52303's avatar
    krelm_52303
    Icon for Nimbostratus rankNimbostratus
    Feb 25, 2009
    Oooops, didn't read the wiki properly. The DNS_Request event is only available on a GTM, not LTM.

     

     

    So, back to the drawing board. Any ideas gladly received.
  • JRahm's avatar
    JRahm
    Icon for Admin rankAdmin
    Feb 25, 2009
    These two posts may help you get started:

     

     

    https://devcentral.f5.com/Default.aspx?tabid=53&forumid=5&postid=6760&view=topic Click here

     

     

    https://devcentral.f5.com/Default.aspx?tabid=53&forumid=5&postid=5557&view=topic Click here