Use FPM

 

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From: [email protected]
[mailto:[email protected]] On Behalf Of Kingsley
Charles
Sent: Monday, November 15, 2010 10:26 AM
To: Pieter-Jan Nefkens
Cc: OSL Security
Subject: Re: [OSL | CCIE_Security] Controlling fragmented packets to control
plane

 

Tried that too PJ but that also doesn't work .

There should be protocols that uses process switching with cef configured
otherwise why would Cisco have a transit interface for CPPr?


With regards
Kings

On Mon, Nov 15, 2010 at 8:42 PM, Pieter-Jan Nefkens
<[email protected]> wrote:

Hi kings,

 

What if you enable cef globally but disable on an ingress interface?

 

Pj

Sent from an iPhone


Op 15 nov. 2010 om 15:33 heeft Kingsley Charles <[email protected]>
het volgende geschreven:

Hi PJ 

CPPr requires cef, if you disable cef, all the three CPPr sub-interfaces are
disabled and you will see the the following message on the console:

On contrast CoPP can work without CEF. 

I am looking for a feature or traffic that uses process switch with CEF
enabled on the router.

router2(config)#no ip cef
router2(config)#
Nov 13 12:17:09.667: %CP-4-CPPR_DISABLED: Removing security features on
host, tr
ansit and cef-exception paths
router2(config)#
router2(config)#
Nov 13 12:17:09.667: %CP-5-FEATURE: Control-plane Policing feature disabled
from
 Control plane host path

Nov 13 12:17:09.667: %CP-5-FEATURE: Control-plane Policing feature disabled
from
 Control plane transit path

Nov 13 12:17:09.667: %CP-5-FEATURE: Control-plane Policing feature disabled
from
 Control plane cef-exception path


With regards
Kings

On Mon, Nov 15, 2010 at 2:05 PM, Pieter-Jan Nefkens
<[email protected]> wrote:

Hi kings,

 

You can disable cef completely by using global config (issue 3)

 

No ip cef

 

You can also use it on interfaces do disable the hardware entries

No ip route-cache flow

 

Hth

 

Pj



Sent from my iPad


On 15 nov. 2010, at 08:59, Kingsley Charles <[email protected]>
wrote:

Hi all

I am trying to block fragmented packets to control plane (both CoPP & CPPr).
Adding one more issue.

Issue 1

    I wanted to simulate fragmented session.

    Let me admit that using ICMP to test CPPr host sub-interface doesn't
seem to be the right way. You need to test with TCP or UDP applications as
CPPr only handles TCP and UDP traffic.

 

    And the other thing I observed is that fragmented ICMP packets doesn't
come into CoPP and is just allowed

    So I tried copying a file of size 2250 KB using ftp, tftp and also
viewed a running config greater 2000 Bytes of another router from my router
that was configured for control plane.

    But none of them seem to be generating fragmented packets.

    I tried configuring the following ACL on the receiving interface to see
for fragmented packets but I didn't see the counters increasing for first
ACE with frag keyword

    access-list 123 permit ip any any fragments
    access-list 123 permit ip any any

    Is there something wrong in the way of my simulation for generating
fragmented packets for ftp, tftp and telnet?


Issue 2

    To get the simulation work, I launched the home page of the router using
a browser and in that I used the extended Ping utility. I self pinged with
size of 2000 bytes and I was able to see the results. The Pings are sent
through HTTP and HTTP which is TCP application is being fragmented. Hence, I
get a simulated fragmented TCP packets to the control plane.


    class-map match-all frag
     match access-group 123

    policy-map frag
     class frag
       drop


    access-list 123 permit ip any any fragments

    If I apply the policy to CoPP, it works. The fragmented packets are
getting dropped.

    control-plane
    service-policy input frag


     If I apply the policy to CPPr host sub-interface. The fragmented
packets are not getting dropped rather all the fragmented packets are
classified in  the  default class which means control plane host doesn't
match fragmented packets.

     control-plane host
     service-policy input frag

     router2#sh policy-map control-plane host
 Control Plane Host

  Service-policy input: frag

    Class-map: frag (match-all)
      0 packets, 0 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: access-group 123
      drop

    Class-map: class-default (match-any)
      127 packets, 13237 bytes
      5 minute offered rate 0 bps, drop rate 0 bps
      Match: any
   
   Why isn't control plane host sub-interface handle fragmented packets?


Issue 3

I am trying block fragmented packets using transit plane.

The transit sub-interface only deals with process switched traffic. Hence I
put a router behind the router configured for the control transit plane and
cleared the arp-cache. Now I tried to ping that router which is behind and
since there is no ARP cache, thereby do CEF table populated, the router
configured for control plane process switches the Ping and hence, I get a
simulated process switched ping. 

But I am not able to continue with this process switched ping with
fragmented packets as there is no ARP. Once I configure ARP manually, the
CEF table is built and fragmented packets are CEF switched, thereby
permitted

Can someone tell me a way to test fragmented process switch traffic across
the transit sub-interface.





With regards
Kings

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