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Cisco Bug: CSCut41765 - IPSG - Some DNS requests are being wrongly matched

Last Modified

Dec 25, 2016

Products (1)

  • Cisco ASR 5000 Series

Known Affected Releases

16.0(1)

Description (partial)

Symptom:
Under:

 rulebase mm-autogestion

      action priority 400 ruledef validDNS-1 charging-action rg10
      action priority 405 ruledef notValidDNS-1 charging-action rg500
      action priority 410 ruledef validDNS-2 charging-action rg10
      action priority 415 ruledef notValidDNS-2 charging-action rg500
      action priority 420 ruledef defaultDns charging-action rg11

where:

ruledef validDNS-1
      ip server-ip-address range host-pool entelDnsServers
      udp either-port = 53
      dns query-name !ends-with your-freedom.de
      ip total-length <= 200
    #exit
    ruledef validDNS-2
      ip server-ip-address range host-pool entelDnsServers-2
      udp either-port = 53
      dns query-name !ends-with your-freedom.de
      ip total-length <= 200


 ruledef notValidDNS-1
      ip server-ip-address range host-pool entelDnsServers
      udp either-port = 53
      ip total-length >= 200
    #exit
    ruledef notValidDNS-2
      ip server-ip-address range host-pool entelDnsServers-2
      udp either-port = 53
      ip total-length >= 200
    #exit

    ruledef defaultDns
      udp either-port = 53
      tcp either-port = 53
      multi-line-or all-lines
      
	host-pool entelDnsServers
      ip 164.77.252.215/32
      ip 164.77.252.249/32
      ip 164.77.252.197/32
      ip 164.77.252.198/32
      ip 172.18.236.99/32
      ip 172.18.150.35/32
      ip 200.111.86.10/32
      ip 200.63.56.3/32
      ip 200.63.56.4/32
      ip 200.63.56.5/32
    #exit
    host-pool entelDnsServers-2
      ip 164.77.252.202/32

We have:

Tuesday March 17 2015
INBOUND>>>>>  15:07:29:305 Eventid:51000(0)
IPv4 Rx PDU
10.209.16.116.34934 > 172.18.236.99.53:  [udp sum ok] 38173+ A? clients3.google.com. [|domain] (DF) [tos 0x28]  (ttl 63, id 14705, len 65)
 
Tuesday March 17 2015
<<<<OUTBOUND  15:07:29:305 Eventid:77000(9)
CSS Uplink Output PDU to ACS- slot:2 cpu:17 inst:4369
10.209.16.116.34934 > 172.18.236.99.53:  [udp sum ok] 38173+ A? clients3.google.com. [|domain] (DF) [tos 0x28]  (ttl 63, id 14705, len 65)
 
Tuesday March 17 2015
***CONTROL*** 15:07:29:305 Eventid:77202
Rule matched : defaultDns for uplink packet of subscriber MSID : (null)

The defaultDns rule is matching where entelDnsServers should match.

Conditions:
Random
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  • Status
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