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Managing DNS for Remote VPN Users in AWS Route53 with VNS3
Managing DNS can be a fairly complex and daunting task. Installing and configuring Bind takes time and knowledge and requires maintenance. Infoblox is expensive and likely overkill for smaller projects. Cloud vendors like AWS have simplified offerings that allow ease of use and scale with your needs. They offer public and private zone management with features like split horizon. Split horizon allows Domain Name Systems to provide different information based on the source address of the requestor. For example, if you are coming from the internet at large you would receive the public IP address of the named system you are looking up, but if you were in the same private subnet as that system you would receive it’s private IP address. This allows you to define the how users get to systems depending on where they are.
Let’s take the example of a remote VPN connection. With VNS3 People VPN you can easily connect your workforce to your cloud assets, be they across regions and or vendors. Giving you a secure entry point to your companies computational resources. VNS3 makes it easy to push DNS settings to connected clients so that they are told that their DNS server is the address of the VNS3 security controller. So now we have connected clients making DNS calls to VNS3. But hold on VNS3 isn’t a DNS server. Well it can be through it’s plugin system, but thats a different topic for another blog post. In this scenario we can divert all incoming DNS traffic through use of the VNS3 firewall.
PREROUTING_CUST -i tun0 -p tcp -s 172.16.0.0/24 –dport 53 -j DNAT –to 10.0.0.2:53
PREROUTING_CUST -i tun0 -p udp -s 172.16.0.0/24 –dport 53 -j DNAT –to 10.0.0.2:53
Here we are saying that traffic coming in on the tun0 interface (overlay network) from 172.16.0.0/24 (overlay address space) bound for UDP and TCP port 53 (DNS) should be forwarded to 10.0.0.2 on UDP and TCP port 53 (AWS VPC DNS endpoint).
Ok so now that we have our remote VPN DNS requests being diverted to the VPC DNS endpoint we need to configure our responses. In Route53 you can configure any zone name you want so long as it isprivate. For public zones you will need to own the domain name. But for private zones you can do whatyou want. This can be very useful where you might have a secure IPSec connection to a partner network and want to use DNS names that reflect your partners name and configure addresses across your tunnels. You can set up as many private zones as you want. Once they have been setup it is now just a mater of associating them with the VPC that your VNS3 security controller resides in. you will now have custom DNS naming for your remote workforce.