Tag: access list

Unidirectional communication filter between two VLANs

Block Traffic among two VLAN’s but only in one way, how to do that?

VLAN and VLAN configurations are very useful in all kinds of different ways. This configuration will be useful sooner or later for all network administrators out there.

UPDATE on 01 Sep 2017:
This article is about reflexive access-list which enable some sort of false statefulness for TCP traffic going through your router. After some feedbacks from my readers, I wrote another, a bit better article about reflexive access-list configuration so I suggest reading the other one as well.

It was a big challenge to resolve this tricky communication security requirement. The problem actually does not seem like a big deal but when you try to make it work you see that it is.


The goal was to make unidirectional communication filter between two VLANs. The request was to allow VLAN 10 to access VLAN 20 but not the opposite. The computers from VLAN 10 needed to access resources in VLAN 20 normally but computers from VLAN 20 had to be prevented to access VLAN 10. 

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