Egress Control Filter

Why is egress control filter needed?

fqdn

For Internet bound egress traffic, specifying outbound policy at IP address level is not sufficient as the domain names of a site can be translated to many different IP addresses.

AWS NAT gateway does not offer security group function, it relies on security groups by each instance. AWS NAT instance’s security group does not have enough entries to support the large set of IP address list. The egress filtering needs to happen at Layer 7.

On the other hand, workloads in AWS are mostly applications where it is deterministic which outbound APIs the application program calls. For example, the application runs API queries to www.salesforce.com for data retrieving; the application also runs API queries to www.google.com for app authentication. In these cases, making sure only these sites are allowed for egress traffic is sufficient from security point of view. Note this is very different from on-prem situation where end user traffic and application traffic are mingled together, you may need a full fledged firewall for Internet bound traffic.

What does Aviatrix FQDN feature do?

Aviatrix Fully Qualified Domain Name (FQDN) Whitelisting is a security feature specially designed for workloads in public cloud. It filters Internet bound egress traffic initiated from workloads in a VPC.

Aviatrix FQDN Whitelisting filters on HTTP and HTTPS traffic and allows only the destination host names (whitelist) specified in the list to pass and drop all other destinations. Each host name is specified as fully qualified domain name. For example, if you only allow Internet bound traffic to www.salesforce.com, you can list the domain name in the whitelist. It also supports wild card, such as *. In this example, you can specify *.salesforce.com to allow traffic to any domain names that ends salesforce.com.

Note the gateway must have NAT enabled if you want to turn on FQDN whitelists.

How does it work?

This features works for HTTP and HTTPS traffic to public Internet. The function is carried out inline without requiring any certificate or keys to decrypt the traffic.

A tag is defined as a list of FQDNs and it is created and managed on the Controller console. One or more gateways is attached to a tag. Each gateway can be attached to one tag. Any updates to a tag on the Controller automatically triggers updates to all gateways attached to the tag.

Multiple tags can be defined for the controller. The domains in the tag are the destinations that are allowed for traffic to pass.

Configuration Workflow

Important

The VPC you want to apply FQDN filter must have an Aviatrix gateway launched with NAT enabled before starting the following steps.

Step 1. Add a new tag

Go Security -> FQDN, click New Tag, as shown below:

fqdn-new-tag

Click “+New Tag”, and enter a name for the tag, for example, prod-whitelist, as shown below:

fqdn-add-new-tag

Step 2. Add URL list to the new tag

Enable the new tag and click Edit, as shown below:

fqdn-enable-edit

Click “+Add New” to add each URL, wild card is allowed, as shown below:

fqdn-add-domain-names

Step 3. Attach to gateways

Click “Attach Gateway” to attach a gateway to the tag.

When a gateway is attached to a tag, in the tag will be pushed for enforcement (whitelist or blacklist), as shown below.

fqdn-attach-spoke1

Repeat Step 3 if you have more gateways that should be attached to this tag.

fqdn-attach-spoke2

Add more tags

Repeat from Step 1 to create more tags and attach different gateways. Note each gateway can only be attached to one tag.

For support, send email to support@aviatrix.com

Enjoy!