How to create a Access list on core switch to bloxk all Internet Traffic & allow some specific Internet Traffic
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08-18-2013 05:09 AM - edited 02-21-2020 04:57 AM
Hellp Everyone,
I am trying to create a Access-List on my Core Switch, in which I want to allow few internet website & block the rest of them.
I want to allow the whole Intranet but few intranet websites also needs access to the internet.
Can we create such Access-List with the above requirement.
I tried to create the ACL on the switch but it blocks the whole internet access.
i want to do it for a subnet not for a specific IP.
Can someone help me in creating such access list.
Thanks in Advance
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08-18-2013 07:19 AM
The exact syntax depends on your subnets and how they connect to the Internet. If you can share a simple diagram that would be much more informative.
In general just remember that access-lists are parsed from the top down and as soon as a match is found, the processing stops. So you put the most specific rules at the top. also, once you add an access-list, there is an implicit "deny any any" at the end.
The best approach is to create some network object-groups and then refer to them in your access list. From your description, that would be something like three object-groups - one for the Intranet (Intranet), one for the allowed servers that can use Internet (allowed_servers), and a third for the permitted Internet sites (allowed_sites).
You would then use them as follows:
ip access-list extended main_acl
permit any object-group intranet any
permit object-group allowed_servers object-group allowed_sites any
interface vlan
ip access-group main_acl in
More details on the syntax and examples can be found here:
