Introduction
The purpose of this document is to provide you an example of how to block any website, like facebook, using the local content filtering on Cisco IOS based routers.
Problem Description
We are faced with a challenge of blocking the social media/any website on the router towards the edge of the network so that no one from inside the network can connect to the blocked site. Generally you would be using a websense or n2h2 or trend micro server to filter out the traffic, however, you want to configure this locally on the IOS of the router.
Solution
The following example considers that you have a fair understanding of configuring zone based firewall (ZBF) on the Cisco IOS routers. Please enter the following configurations to block the website "facebook" based on pattern "*.facebook.com" or "facebook.com".
This section specifies content filtering to be "local" on the IOS. The other options are to use "trend", "n2h2", and "websense".
parameter-map type urlfpolicy local U-FILTER
alert off
block-page message "This webpage is blocked by the Network Admin."
!
This section specifies content filtering pattern to match the desired site, like, facebook.
parameter-map type urlf-glob FB
pattern facebook.com
pattern *.facebook.com
!
This section specifies content filtering pattern to match all the other sites, so that we can permit them later.
parameter-map type urlf-glob ALLOWED
pattern *
!
This section specifies content filtering filter class to match the pattern that we created earlier.
class-map type urlfilter match-any BLOCK
match server-domain urlf-glob FB
class-map type urlfilter match-any ALLOWED
match server-domain urlf-glob ALLOWED
!
This section specifies the traffic that the Cisco IOS will inspect or match.
class-map type inspect match-any DNS
match protocol dns
class-map type inspect match-any HTTP
match protocol http
class-map match-all HTTPS
match protocol secure-http
class-map type inspect match-all HTTPS1
match protocol https
!
This section specifies a policy map that will tie the filter classes and the action to be taken.
policy-map type inspect urlfilter BLOCK
parameter type urlfpolicy local U-FILTER
class type urlfilter BLOCK
log
reset
class type urlfilter ALLOW
allow
!
This section specifies the traffic class and its inspection.
policy-map type inspect INOUT
class type inspect HTTP
inspect
service-policy urlfilter BLOCK
class type inspect DNS
inspect
class type inspect HTTPS1
inspect
class class-default
drop
!
This section ties the inspection service policy to the zone-pair.
zone-pair security xxxxxx source xxxx destination yyyy
service-policy type inspect INOUT
Related Information
For more information on content based filtering overall, please refer to:
http://www.cisco.com/en/US/docs/ios-xml/ios/sec_data_zbf/configuration/12-4t/subscrip-cont-filter.html
