Inter VLAN routing - best practices/suggestions

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L1 Bithead

Inter VLAN routing - best practices/suggestions

Hi guys, I've got about 7 or 8 VLANs that segregate my various departments. I want to inspect the traffic that goes from these VLANs to my server VLAN. What's the best way to do that? The only article I could find suggests creating a zone for each department. They are all currently configured as Layer3 subinterfaces on the same VR but this isn't production yet so I can move stuff around if need be.

 

Current Interface Config.JPG

L7 Applicator

Re: Inter VLAN routing - best practices/suggestions

@Konos44,

You would either do what the article said and create a zone for each department; or you would override the intra-zone default security policy to 'deny' and build out security policies to permit what is required. Easiest solution from a maintenance perspective is going to be creating new zones. 

One option as well is to create 1 sole additional zone specifically for your 'server' VLAN. You would then have your 'Inside' zone and your server VLAN interface would belong to the 'Server' zone. Therefore any traffic between the Server VLAN and the others would require a security policy. 

L1 Bithead

Re: Inter VLAN routing - best practices/suggestions

Thanks for comment. Is there any kind of list with "typical" ports or applications (I guess in the case of the PA as it is app aware) that one can reference to help make this process go a little faster and smoother? For example I'd want DNS, DHCP, http/https as well as file server services to be allowed but the only way I can think of doing this is by doing a DENY and just slowly go through the logs and ALLOW each service/application that I want.

L7 Applicator

Re: Inter VLAN routing - best practices/suggestions

@Konos44,

Not that I'm aware of, as it all kind of depends on your general enviroment. You should be able to build a half decent config looking at what's currently allowed in the ASA however, the migration tool can assist with this in a rough fasion. System owners should have a rough idea of what they need open for internal clients accessing the server VLAN. 

Depending on the security implications you could simply allow all traffic from the 'Inside' to the 'Server' zones and vise versa; as that is likely what you are doing now based on your configuration. You then have time to build out legitimate security policies and place them above your 'any' rule; once that 'any' rule is only getting hit by unknown or acceptable levels of traffic you simply remove it and let the policies you built out control traffic. 

L1 Bithead

Re: Inter VLAN routing - best practices/suggestions

Oh I like that idea... Maybe start with a couple of my more tech-friendly users as well just to get a head start. 

 

Thanks for the suggestions.

L4 Transporter

Re: Inter VLAN routing - best practices/suggestions

To add to BPry's recommendation, if you know the servers that will see traffoc (You probably do) you can implement rules for them that allow any application and let it run 30-60 days.  You can then use the migration tool to assign app-ids from he logs (I do not have the instructions handy, but they should be out there) - I've done this a number of times with great sucess

 

Alternately, I've used Splunk to map the most common applications and endpoints from the logs, to begin building specific rules from that

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