Fa0/0 0.0.0.0 Null 255.255.255.255

sravan_235 · ‎02-19-2007

Here iam enclosing sh ip cache flow output of a router.

My question is ,what do you mean by NULL interface.why these type traffic is flowing in a router .

Fa0/1 0.0.0.0 Null 255.255.255.255 11 0044 0043 1

Fa0/0 0.0.0.0 Null 255.255.255.255 11 0044 0043 1

Fa0/0 10.17.1.198 Null 255.255.255.255 11 0208 0208 1

Fa0/1 10.17.1.198 Null 255.255.255.255 11 0208 0208 1

Fa0/0 10.17.1.197 Null 224.0.0.9 11 0208 0208 1

spremkumar · ‎02-19-2007

Hi

The port numbers indicate the packets are being destined to port 67 and port 520.

(520 - extended file name server,

67 - Bootstrap Protocol Server)

Port belongs 520 to extended file name server and Port 67 belongs to Bootstrap Protocol Server..

regds

sravan_235 · ‎02-19-2007

hi Prem,

How you know these belongs to 520 and 67 ports.

sravan kumar

spremkumar · ‎02-19-2007

Hi

Those ports are mentioned in Hexa-Decimal numbers you can decode them using our normal basic extended calculator..

regds

gokula_chandran · ‎02-19-2007

Please go through the url you can have a better uhttp://cisco.com/en/US/products/ps5845/products_configuration_guide_chapter09186a00806f4e85.html#wp1329626nderstanding of using Null interface

shantharam.suryanarayana · ‎02-19-2007

Hi sravan,

Meaning of NULL interface is the packets dropped because of ACL. The below link gives you the information

http://cisco.com/en/US/tech/tk812/technologies_white_paper09186a008022bde8.shtmlc

Regards

S. Shantharam

sravan_235 · ‎02-20-2007

Hi,

Suryananraya,

Iam not able to open your URL.

Regards

sravan kumar

sravan_235 · ‎02-20-2007

hi to all,

My main intention is to block 172.0.0.0 0.255.255.255 traffic.For this i have created ACL as deny ip 172.0.0.0 0.255.255.255 any ..But when i run the command "sh ip cache flow i can see the 172 series ip address traffic.

So please help in this regard . how can i block the traffic of 172 serices.

Out put if "sh ip cache flow " here enlosed.

SrcIf SrcIPaddress DstIf DstIPaddress Pr SrcP DstP Pkts

Se5/2 172.16.19.1 Null 172.23.142.126 01 0000 0000 65

Se5/2 172.23.170.16 Null 172.23.142.207 06 1266 01BD 1

Se5/2 172.23.170.16 Null 172.23.142.81 06 1242 01BD 1

Se5/2 172.23.170.17 Null 172.23.142.250 06 0408 01BD 1

shantharam.suryanarayana · ‎02-20-2007

Hi Saravana,

Please try this link

http://cisco.com/en/US/tech/tk812/technologies_white_paper09186a008022bde8.shtml

Regards

S. Shantharam

sravan_235 · ‎02-20-2007

Hi all,

How can i stop this traffic.

Fa0/1 0.0.0.0 Null 255.255.255.255 11 0044 0043 1

Fa0/0 0.0.0.0 Null 255.255.255.255 11 0044 0043 1

Fa0/0 10.17.1.198 Null 255.255.255.255 11 0208 0208 1

Fa0/1 10.17.1.198 Null 255.255.255.255 11 0208 0208 1

Fa0/0 10.17.1.197 Null 224.0.0.9 11 0208 0208 1

plese help me what are the command will stop the unwanted virus traffic.

regards

sravan