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eightsixstud_29's avatar
eightsixstud_29
Icon for Nimbostratus rankNimbostratus
Sep 15, 2016
Solved

Error using iRule for Conditional DNS Lookups

I am looking to perform some DNS lookups on a domain and based on the results, either provide the client with the external IP if it exists or the internal IP if there isn't an external A record.

 

I have written the following irule but am receiving this error:

 

"01070151:3: Rule [/Common/Conditional_Test_Lookup] error: /Common/Conditional_Test_Lookup:2: error: [undefined procedure: DNS::rrname][DNS::rrname] /Common/Conditional_Test_Lookup:4: error: [parse error: PARSE syntax 258 {syntax error in expression " $dnsName [DNS::rrtype] equal "A" ": extra tokens at end of expression}][{ $dnsName [DNS::rrtype] equal "A" }] "

 

Code:  
when DNS_REQUEST {
        if { ([IP::addr [IP::client_addr] equals 192.168.1.0/24]) and ([DNS::rrname] contains "test.com") } {
                            set dnsName [RESOLV::lookup @8.8.8.8 -a [DNS::rrname]] 
                            if { $dnsName [DNS::rrtype] equal "A" } {
                                DNS::return
                            } 
            }
}
application delivery
BIG-IP DNS
iRules
  • Samir_Jha_52506's avatar
    Samir_Jha_52506
    Sep 15, 2016

    HI,

    Can you please try below irule.

       when DNS_REQUEST {
    if { ([IP::addr [IP::client_addr] equals 192.168.1.0/24]) and ([DNS::rrname] contains "test.com") } {
                        set dnsName [RESOLV::lookup @8.8.8.8 -a [DNS::rrname]] 
                        if { ([DNS::rrtype] equal "A") } {
                            DNS::return
                        } 
        }
    }

3 Replies

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  • R_Marc's avatar
    R_Marc
    Icon for Nimbostratus rankNimbostratus
    Sep 15, 2016

    Not sure how relevant this is, but for me, I had to create a local virtual to get Resolve to work consistently. Going direct actually caused all DNS to stop working on the box (TMos and Linux).

    [RESOLV::lookup @/Common/dns-proxy-ipv4-dns-virtual -a $name]
  • Samir_Jha_52506's avatar
    Samir_Jha_52506
    Icon for Noctilucent rankNoctilucent
    Sep 15, 2016

    HI,

    Can you please try below irule.

       when DNS_REQUEST {
    if { ([IP::addr [IP::client_addr] equals 192.168.1.0/24]) and ([DNS::rrname] contains "test.com") } {
                        set dnsName [RESOLV::lookup @8.8.8.8 -a [DNS::rrname]] 
                        if { ([DNS::rrtype] equal "A") } {
                            DNS::return
                        } 
        }
    }
    • eightsixstud_29's avatar
      eightsixstud_29
      Icon for Nimbostratus rankNimbostratus
      Sep 19, 2016

      We tried using the modified version, but are receiving the same error. Also, we have made the below changes, with no luck. Any ideas? 

      01070151:3: Rule [/Common/Test] error: /Common/Test:2: error: [undefined procedure: DNS::rrname][DNS::rrname]
/Common/Test:4: error: [undefined procedure: DNS::rrtype][DNS::rrtype]

when DNS_REQUEST {
if { ([IP::addr [IP::client_addr] equals 192.168.1.0/24]) and ([DNS::rrname] equals "test.com") } {
                    [RESOLV::lookup @8.8.8.8 -a [DNS::rrname]] 
                    if { ([DNS::rrtype] equals "A") } {
                        DNS::return
                    } 
    }
}