This topic is to discuss the following lesson:
is this how most companies block access, i think we use something called websense?
also with facbeook having so many webservers in a farm for redundancy would you in real world scendario block by ip, or hostname?
The time based access-list is basically the “poor man’s” solution to block access on routers. You can use access-lists only to filter on L3/L4 information (IP addresses, protocols and port numbers) so you can’t filter based on hostnames.
One way to get around this is to block all prefixes that belong to a certain AS. For example, facebook uses AS 32934. We can find their prefixes with whois:
$ whois -h whois.radb.net -- '-i origin AS32934' | grep 'route:' route: 18.104.22.168/22 route: 22.214.171.124/20 route: 126.96.36.199/20 route: 188.8.131.52/21 route: 184.108.40.206/21 route: 220.127.116.11/21 route: 18.104.22.168/22 route: 22.214.171.124/24 route: 126.96.36.199/18 route: 188.8.131.52/19 route: 184.108.40.206/20 route: 220.127.116.11/22 route: 18.104.22.168/24 route: 22.214.171.124/19 route: 126.96.36.199/24 route: 188.8.131.52/18 route: 184.108.40.206/21 route: 220.127.116.11/21 route: 18.104.22.168/24 route: 22.214.171.124/24 route: 126.96.36.199/20 route: 188.8.131.52/19 route: 184.108.40.206/24 route: 220.127.116.11/24 route: 18.104.22.168/24 route: 22.214.171.124/24 route: 126.96.36.199/24 route: 188.8.131.52/24 route: 184.108.40.206/24 route: 220.127.116.11/24 route: 18.104.22.168/24 route: 22.214.171.124/24 route: 126.96.36.199/24 route: 188.8.131.52/24 route: 184.108.40.206/24 route: 220.127.116.11/19 route: 18.104.22.168/24 route: 22.214.171.124/19 route: 126.96.36.199/24 route: 188.8.131.52/24 route: 184.108.40.206/24 route: 220.127.116.11/24 route: 18.104.22.168/24 route: 22.214.171.124/24 route: 126.96.36.199/24 route: 188.8.131.52/24 route: 184.108.40.206/24 route: 220.127.116.11/24 route: 18.104.22.168/24 route: 22.214.171.124/24 route: 126.96.36.199/24 route: 188.8.131.52/24 route: 184.108.40.206/24 route: 220.127.116.11/24 route: 18.104.22.168/24 route: 22.214.171.124/24 route: 126.96.36.199/24 route: 188.8.131.52/24 route: 184.108.40.206/24 route: 220.127.116.11/22 route: 18.104.22.168/24 route: 22.214.171.124/24 route: 126.96.36.199/24 route: 188.8.131.52/24 route: 184.108.40.206/22 route: 220.127.116.11/22 route: 18.104.22.168/24 route: 22.214.171.124/24 route: 126.96.36.199/24 route: 188.8.131.52/24 route: 184.108.40.206/16 route: 220.127.116.11/16 route: 18.104.22.168/22 route: 22.214.171.124/20 route: 126.96.36.199/21 route: 188.8.131.52/21 route: 184.108.40.206/20 route: 220.127.116.11/20
You could create a script that fetches these prefixes and updates your access-list every now and then.
For some more “serious” security, we use firewalls. Some firewalls are able to inspect the application layer so we can drop traffic based on the URL, payload, etc.
Thanks for your article…
What will be the command periodic if we want to block traffic from Sunday to Thrusday ?
You can use some of the default periodic options:
Router(config-time-range)#periodic ? Friday Friday Monday Monday Saturday Saturday Sunday Sunday Thursday Thursday Tuesday Tuesday Wednesday Wednesday daily Every day of the week weekdays Monday thru Friday weekend Saturday and Sunday
In our client network,
The Cisco Layer 2 Switch 2960G port 15 which is connected to the L2VPN MPLS-TP network and each month or time not remembering , the port is getting down and they are changing the port to other 16 Which was also configured for the same service. Once contractor was done this but client want to know if there is any time based port security is enable or no, Kindly share your advise.