Don't recall where I found this on the web but I came across it a couple months
ago when our security manager was looking at blocking/shaping Skype. So for
those running Cisco routers this might solve your problems.
_________________________________________________________________________________________________________________________
On April 4th 2006, Cisco released IOS version 12.4 (4) T. Cisco introduced much
awaited Skype classification in NBAR . So now with simple policy you can block
skype. Skype can be blocked in a similar way as we use to block kazza,limewire
and other p2p applications.
Example:-
NBAR configuration to drop Skype packets
classâmap matchâany p2p
match protocol skype
policyâmap blockâp2p
class p2p
drop
int FastEthernet0
description PIXâfacing interface
serviceâpolicy input blockâp2p
If you are unsure about the bandwidth eating applications being used in your
organisation. you can access the interface connected to the Internet and
configure following command
ip nbar protocol-discovery.
This will enable nbar discovery on your router.
Use following command:-
show ip nbar protocol-discovery stats bit-rate top-n 10
it will show you top 10 bandwidth eating applications being used by the users.
Now you will be able to block/restrict traffic with appropriate QoS policy.
we can also use ip nbar port-map command to look for the protocol or protocol
name, using a port number or numbers other than the well-known Internet
Assigned Numbers Authority (IANA)-assigned) port numbers.
Usage as per cisco:-
ip nbar port-map protocol-name [tcp | udp] port-number
Up to 16 ports can be specified with this command. Port number values can range
from 0 to 65535
____________________________________________________________________________________________________
Rgrds,
Wayne Dobby
Network Specialist
ICT | WorleyParsons | www.worleyparsons.com
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