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Step-by-Step Configuration and Troubleshooting Best Practices for the NGFW, NGIPS and AMP Technologies A Visual Guide to the Cisco Firepower Threat Defense (FTD)
New Member

AIP-SSM 420002 - IPS requested to drop TCP packet from 'source' to 'destination'

Hi guys,

I have an asa 5510 with aip-ssm installed. I have a DMZ with security level 90 where a web server is located.

When AIP-SSM is in inline mode i get the following message 4    Oct 05 2010    14:37:15        WEB    80    x.x.x.x    30115    IPS requested to drop TCP packet from WEB-DMZ:WEB/80 to OUTSIDE:x.x.x.x/30115

From what i can see the message apears many times with source interface the WEB-DMZ and destination either outside,inside or other dmz interface depending of who is requesting access to the web server.

The result is that the web server isnt accessible either from outside or inside.

The syslog id that i am getting is the 420002 but i didn't find any logical explation of why this id is triggered.

Any help ?

Thanks.

16 REPLIES
Cisco Employee

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

Hi,

Can you look at the events in the AIP SSM module and see what signature is being triggered when trying to access that particular server? Please do paste the event details here.


Thanks and Regards,

Prapanch

New Member

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

Hi,

This is really strange cause i cannot see any relative signature firing up The only signature that fires up is about the edonkey activity which is false positive and has as source and destination ip's the web server's and active directory only.

Thanks for your help.

Cisco Employee

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

Hi,

That's weird. You should be seeing a signature firing up with a drop action configured. Have you tried bypassing the IPS module and see if web server is accessible?

Thanks and Regards,

Prapanch

New Member

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

When AIP-SSM is operating is passive mode, everything is working fine. With the bypass feature on Auto mode still i get the same message.

One thing i have noticed is that my web server appears always as the source on the 420002 message.

Still, none can't access the web server when AIP-SSM is in inline mode.

Cisco Employee

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

Hi,

We should be seeing some signature firing. As a possible workaround, you can deny all traffic from/to the web server from being re-directed to the AIP SSM module. You will need to specify an ACL with a deny statement for the web server and a "permit ip any any" under the class-map configured for the ips.

Let me know if this helps!

Thanks and Regards,

Prapanch

New Member

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

What will i accomplish with that ? I want to inspect the traffic destined to the web server.

Cisco Employee

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

Hi,

Can you paste the output of "show statictics virtual-sensor"? Under this you should see the number of hits per signature. Based on this we can disable each of the signatures and see which one is exactly causing the bahvior we are seeing.

Thanks and Regards,

Prapanch

New Member

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

I understand that the bold part is the one that we are interested in.I can see now that many signatures where firing up blocking hosts but why they didn's show up on the IPS Manager ?

Here is the output :

Virtual Sensor Statistics
   Statistics for Virtual Sensor vs0
      Name of current Signature-Defintion instance = sig0
      Name of current Event-Action-Rules instance = rules0
      List of interfaces monitored by this virtual sensor = GigabitEthernet0/1 subinterface 0
      General Statistics for this Virtual Sensor
         Number of seconds since a reset of the statistics = 4406885
         MemoryAlloPercent = 52
         MemoryUsedPercent = 49
         MemoryMaxCapacity = 600000
         MemoryMaxHighUsed = 444416
         MemoryCurrentAllo = 314134
         MemoryCurrentUsed = 299241
         Processing Load Percentage = 1
         Total packets processed since reset = 1708939018
         Total IP packets processed since reset = 1708939018
         Total IPv4 packets processed since reset = 1708939018
         Total IPv6 packets processed since reset = 0
         Total IPv6 AH packets processed since reset = 0
         Total IPv6 ESP packets processed since reset = 0
         Total IPv6 Fragment packets processed since reset = 0
         Total IPv6 Routing Header packets processed since reset = 0
         Total IPv6 ICMP packets processed since reset = 0
         Total packets that were not IP processed since reset = 0
Total TCP packets processed since reset = 1706764676
         Total UDP packets processed since reset = 2174321
         Total ICMP packets processed since reset = 21
         Total packets that were not TCP, UDP, or ICMP processed since reset = 0
         Total ARP packets processed since reset = 0
         Total ISL encapsulated packets processed since reset = 0
         Total 802.1q encapsulated packets processed since reset = 0
         Total packets with bad IP checksums processed since reset = 0
         Total packets with bad layer 4 checksums processed since reset = 0
         Total number of bytes processed since reset = 1441199516738
         The rate of packets per second since reset = 387
         The rate of bytes per second since reset = 327033
         The average bytes per packet since reset = 843
      Denied Address Information
         Number of Active Denied Attackers = 0
         Number of Denied Attackers Inserted = 9
         Number of Denied Attacker Victim Pairs Inserted = 0
         Number of Denied Attacker Service Pairs Inserted = 0
         Number of Denied Attackers Total Hits = 6460
         Number of times max-denied-attackers limited creation of new entry = 0
         Number of exec Clear commands during uptime = 0
      Denied Attackers and hit count for each.
      Denied Attackers with percent denied and hit count for each.

The Signature Database Statistics.
         The Number of each type of node active in the system
            Total nodes active = 229
            TCP nodes keyed on both IP addresses and both ports = 58
            UDP nodes keyed on both IP addresses and both ports = 27
            IP nodes keyed on both IP addresses = 6
         The number of each type of node inserted since reset
            Total nodes inserted = 4205743
            TCP nodes keyed on both IP addresses and both ports = 668125
            UDP nodes keyed on both IP addresses and both ports = 1084132
            IP nodes keyed on both IP addresses = 198488
         The rate of nodes per second for each time since reset
            Nodes per second = 0
            TCP nodes keyed on both IP addresses and both ports per second = 0
            UDP nodes keyed on both IP addresses and both ports per second = 0
            IP nodes keyed on both IP addresses per second = 0
         The number of root nodes forced to expire because of memory constraints
            TCP nodes keyed on both IP addresses and both ports = 1302
         Packets dropped because they would exceed Database insertion rate limits = 0
      Fragment Reassembly Unit Statistics for this Virtual Sensor
         Number of fragments currently in FRU = 0
         Number of datagrams currently in FRU = 0
         Number of fragments received since reset = 0
Number of fragments forwarded since reset = 0
         Number of fragments dropped since last reset = 0
         Number of fragments modified since last reset = 0
         Number of complete datagrams reassembled since last reset = 0
         Fragments hitting too many fragments condition since last reset = 0
         Number of overlapping fragments since last reset = 0
         Number of Datagrams too big since last reset = 0
         Number of overwriting fragments since last reset = 0
         Number of Inital fragment missing since last reset = 0
         Fragments hitting the max partial dgrams limit since last reset = 0
         Fragments too small since last reset = 0
         Too many fragments per dgram limit since last reset = 0
         Number of datagram reassembly timeout since last reset = 0
         Too many fragments claiming to be the last since last reset = 0
         Fragments with bad fragment flags since last reset = 0
      TCP Normalizer stage statistics
         Packets Input = 1706719760
         Packets Modified = 0
         Dropped packets from queue = 0
         Dropped packets due to deny-connection = 0
         Duplicate Packets = 0
         Current Streams = 58
         Current Streams Closed = 0
         Current Streams Closing = 0
Current Streams Embryonic = 0
         Current Streams Established = 0
         Current Streams Denied = 0
         Total SendAck Limited Packets = 0
         Total SendAck Limited Streams = 0
         Total SendAck Packets Sent = 0
      Statistics for the TCP Stream Reassembly Unit
         Current Statistics for the TCP Stream Reassembly Unit
            TCP streams currently in the embryonic state = 0
            TCP streams currently in the established state = 0
            TCP streams currently in the closing state = 0
            TCP streams currently in the system = 0
            TCP Packets currently queued for reassembly = 0
         Cumulative Statistics for the TCP Stream Reassembly Unit since reset
            TCP streams that have been tracked since last reset = 0
            TCP streams that had a gap in the sequence jumped = 0
            TCP streams that was abandoned due to a gap in the sequence = 0
            TCP packets that arrived out of sequence order for their stream = 0
            TCP packets that arrived out of state order for their stream = 0
            The rate of TCP connections tracked per second since reset = 0
      SigEvent Preliminary Stage Statistics
         Number of Alerts received = 1603101
         Number of Alerts Consumed by AlertInterval = 643779
         Number of Alerts Consumed by Event Count = 935814

Number of FireOnce First Alerts = 23
         Number of FireOnce Intermediate Alerts = 105
         Number of Summary First Alerts  = 7650
         Number of Summary Intermediate Alerts  = 13410
         Number of Regular Summary Final Alerts  = 2318
         Number of Global Summary Final Alerts  = 0
         Number of Active SigEventDataNodes  = 247
         Number of Alerts Output for further processing = 23508
        Per-Signature SigEvent count since reset
            Sig 3030.0 = 2
            Sig 3051.0 = 297388
            Sig 3051.1 = 637689
            Sig 3327.13 = 5937
            Sig 3653.0 = 56
            Sig 5474.0 = 24
            Sig 5575.0 = 282
            Sig 5579.0 = 4
            Sig 5581.0 = 40
            Sig 5591.0 = 1
            Sig 5606.0 = 162
            Sig 5639.0 = 3
            Sig 5640.2 = 1119
            Sig 5776.3 = 1
            Sig 5813.2 = 3
            Sig 5822.1 = 8
            Sig 6009.0 = 637689
            Sig 6131.6 = 9425
            Sig 6409.2 = 968
            Sig 6984.2 = 154
            Sig 7202.0 = 1977
            Sig 11021.0 = 33
            Sig 11205.0 = 84
            Sig 16297.0 = 162
            Sig 20059.1 = 9890

      SigEvent Action Override Stage Statistics
         Number of Alerts received to Action Override Processor = 2426
         Number Of Meta Components Input = 21082
         Number of Alerts where an override was applied = 227
         Actions Added
            deny-attacker-inline = 0
            deny-attacker-victim-pair-inline = 0
            deny-attacker-service-pair-inline = 0
            deny-connection-inline = 0
            deny-packet-inline = 0
            modify-packet-inline = 0
            log-attacker-packets = 227
            log-pair-packets = 227
            log-victim-packets = 227

produce-alert = 0
            produce-verbose-alert = 143
            request-block-connection = 0
            request-block-host = 0
            request-snmp-trap = 0
            reset-tcp-connection = 0
            request-rate-limit = 0
      SigEvent Action Filter Stage Statistics
         Number of Alerts received to Action Filter Processor = 0
         Number of Alerts where an action was filtered = 408
         Number of Filter Line matches = 408
         Number of Filter Line matches causing decreased DenyPercentage = 0
         Actions Filtered
            deny-attacker-inline = 408
            deny-attacker-victim-pair-inline = 0
            deny-attacker-service-pair-inline = 0
            deny-connection-inline = 0
            deny-packet-inline = 0
            modify-packet-inline = 0
            log-attacker-packets = 0
            log-pair-packets = 0
            log-victim-packets = 0
            produce-alert = 0
            produce-verbose-alert = 0
request-block-connection = 0
            request-block-host = 0
            request-snmp-trap = 0
            reset-tcp-connection = 0
            request-rate-limit = 0
         Filter Hit Counts
            1  = 408
      SigEvent Action Handling Stage Statistics.
         Number of Alerts received to Action Handling Processor = 2425
         Number of Alerts where produceAlert was forced = 0
         Number of Alerts where produceAlert was off = 0
         Number of Alerts using Auto One Way Reset = 0
         Actions Performed
            deny-attacker-inline = 9
            deny-attacker-victim-pair-inline = 0
            deny-attacker-service-pair-inline = 0
            deny-connection-inline = 0
            deny-packet-inline = 0
            modify-packet-inline = 0
            log-attacker-packets = 609
            log-pair-packets = 609
            log-victim-packets = 609
            produce-alert = 2062
            produce-verbose-alert = 799
request-block-connection = 0
            request-block-host = 0
            request-snmp-trap = 0
            reset-tcp-connection = 0
            request-rate-limit = 0
         Deny Actions Requested in Promiscuous Mode
            deny-packet not performed = 0
            deny-connection not performed = 0
            deny-attacker not performed = 1048
            deny-attacker-victim-pair not performed = 0
            deny-attacker-service-pair not performed = 0
            modify-packet not performed = 0
         Number of Alerts where deny-connection was forced for deny-packet action = 0
         Number of Alerts where deny-packet was forced for non-TCP deny-connection action = 0
      Anomaly Detection Statistics
         Number of Received Packets:
            TCP = 1706719760
            UDP = 2173217
            Other = 21
            TOTAL = 1708892998
         Number of Overrun Packets:
            TCP = 0
            UDP = 0
            Other = 0
TOTAL = 0
         Number of Ignored Packets = 0
         Number of Events = 2736
         Number of Recurrent Events:
            TCP = 1622
            UDP = 67
            Other = 1
            TOTAL = 1690
         Number of Worms = 0
         Number of Scanners = 0
         Number of Scanners Under Worm = 0
         Internal Zone
            Number of Events:
               TCP = 0
               UDP = 0
               Other = 0
               TOTAL = 0
            Number of Overrun Events:
               TCP = 0
               UDP = 0
               Other = 0
               TOTAL = 0
         External Zone
            Number of Events:

TCP = 1029
               UDP = 1702
               Other = 5
               TOTAL = 2736
            Number of Overrun Events:
               TCP = 0
               UDP = 0
               Other = 0
               TOTAL = 0
         Illegal Zone
            Number of Events:
               TCP = 0
               UDP = 0
               Other = 0
               TOTAL = 0
            Number of Overrun Events:
               TCP = 0
               UDP = 0
               Other = 0
               TOTAL = 0
         Global Utilization Percentage
            Unestablished Connections DB
               TCP = 0
               UDP = 0
Other = 0
            Recurrent Events DB
               TCP = 0
               UDP = 0
               Other = 0
            Scanners DB
               TCP = 0
               UDP = 0
               Other = 0

Cisco Employee

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

Hi,

Now i am not sure why that is happening. It might be due to the produce alert action being removed. Can you have a check on each of these signatures to see if they have the "produce alert" action removed? If so, please enable that action again. Also, do you have an event action filter configured of some sort?

When trying to access the web server, which of the below counts do you see increasing?

        Per-Signature SigEvent count since reset
             Sig 3030.0 = 2
            Sig 3051.0 = 297388
            Sig  3051.1 = 637689
            Sig 3327.13 = 5937
            Sig  3653.0 = 56
            Sig 5474.0 = 24
            Sig 5575.0 =  282
            Sig 5579.0 = 4
            Sig 5581.0 = 40
             Sig 5591.0 = 1
            Sig 5606.0 = 162
            Sig  5639.0 = 3
            Sig 5640.2 = 1119
            Sig 5776.3 = 1
             Sig 5813.2 = 3
            Sig 5822.1 = 8
            Sig 6009.0 =  637689
            Sig 6131.6 = 9425
            Sig 6409.2 = 968
             Sig 6984.2 = 154
            Sig 7202.0 = 1977
            Sig  11021.0 = 33
            Sig 11205.0 = 84
            Sig 16297.0 =  162
            Sig 20059.1 = 9890

Thanks and Regards,

Prapanch

New Member

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

I have the sensor now inline, i am seeing the top signatures (3051.0-1,6009.0) counters to increase among others, i am not seeing yet any packet to get dropped -that's strange-. The only signature that i see on the IME real time event viewer is 7072 (edonkey traffic),which is a false positive.

I dont see any other signature firing up.

The only thing that i did was to check the produce verbose alert on the top signatures and nothing else.

This is a really strange behaviour...

New Member

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

The counters of those signatures are keep increasing.

Sig 3051.0 = 297388
Sig  3051.1 = 637689

Sig 6009.0 =  637689

I am not seeing any of these signatures on the IPS Manager Real Time Event Viewer.

Cisco Employee

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

Hi,

I hope you have the "produce alert" action configured on all of the signatures that i had mentioned previously. Do you have any "event action filters" or "event action overrides" configured? Could you post snapshots of those?

Also, if it's possible, try disbaling these signatures one-by-one and see if the server becomes accessible at any point.

Thanks and Regards,

Prapanch

New Member

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

Yes, the produce alert action is configured on all signatures. See the attached for the event filter configuration.

As for now, the sensor is in inline mode without dropping any traffic. From the show virtual sensor statistics command i see that the counters of specific signatures are increasing but on the IPS Manager only signature 7072 is shown...

Cisco Employee

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

Hmmm... That's interesting. I would suggest you to open up a TAC case if that's possible to investigate further and look at it live. By the way, have you tried disabling the signatures one at a time to see which one is affecting access to the server? This way we will at least get to know which signature is being triggered.

Thanks and Regards,

Prapanch

Cisco Employee

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

By the way, can you check if there are any "blocked hosts" or "blocked networks" on your IPS sensor? That could be a reason why you are not getting logs though the IPS is requesting packets to be dropped.

Thanks and Regards,

Prapanch

New Member

Re: AIP-SSM 420002 - IPS requested to drop TCP packet from 'sour

No i don't have any blocked hosts or networks, the sensor is working fine now without denying any traffic... :/ , although this is good news i do not understand why the other signatures are not show on the IPS Manager...

Thanks for your help Prapanch.

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