Category: Open Source

DNSDist is a great load balancing DNS forwarder/resolver designed by the same people behind PowerDNS.

It works on Linux and other UNIX OSs, and is fairly easy to set up once you understand how its configuration file works.

An example config with some comments…

controlSocket('127.0.0.1:5199')
setConsoleACL('127.0.0.1/32')
setKey("PUT-KEY-HERE")
addLocal('127.0.0.1')
addLocal('10.0.0.1')
addLocal('::1')
webserver('10.0.0.1:8083', 'dnsdist', 'dnsdist')

This is the initial section defining what IPs DNSDist uses to listen for its control and general purpose sockets:

• controlSocket() – sets local IP and port that the control listens on
• setControlACL() – sets what can connect to the control socket
• setKey() – sets your unique key to prevent unauthorized access
• addLocal() – sets the local IP and port that the resolver listens on
• webserver() – sets the local IP and port that the stats webserver listens on, with the username and password it expects

addDOHLocal("172.16.5.1:5053",
                "/etc/letsencrypt/live/domain.com/fullchain.pem",
                "/etc/letsencrypt/live/domain.com/privkey.pem",
                "/dns-query",
                { doTCP=true, reusePort=true }
                )
doh_ips=newNMG()
doh_ips:addMask('0.0.0.0/0')
doh_ips:addMask('::/0')
addAction(AndRule({NetmaskGroupRule(doh_ips, true), DSTPortRule(5053)}), PoolAction('recursive'))

This section we set up DNS over HTTPS for use with Firefox, Chrome, etc that can take advantage of a secure channel to query DNS separate from their provider’s servers.

In this case, we’re allowing anyone to query over DOH, but you can change that by removing the addMask() covering ‘everything’.

• addDOHLocal() – this sets the local IP and port that the DOH HTTPS server listens on. The paths are to the local letsencrypt generated certificates. The “/dns-query” path is the web server path to use as the base for the queries.
• doh_ips=newNMG() – sets up the Network Mask Group variable
• doh_ips:addMask() – configures the source IP ranges to allow
• addAction() – this one in particular allows anyone from the doh_ips variable who queries DOH on port 5053 to recursive query DNS.

recursive_ips=newNMG()
recursive_ips:addMask('127.0.0.0/8')
recursive_ips:addMask('::1/128')
recursive_ips:addMask('fe80::/10')
recursive_ips:addMask('10.0.0.0/24')
addAction(NetmaskGroupRule(recursive_ips), PoolAction('recursive'))

This section we set up the standard port 53 UDP/TCP resolver to accept queries. It works the same way as the previous block does, with the exception of the addAction().

• addAction() – this allows anyone from recursive_ips variable to query your resolver on port 53 UDP or TCP.

newServer({address="8.8.8.8:53", pool="recursive"})
newServer({address="1.1.1.1:53", pool="recursive"})

recursivepc = newPacketCache(10000, {maxTTL=86400, minTTL=0, temporaryFailureTTL=60, staleTTL=60, dontAge=false})
getPool("recursive"):setCache(recursivepc)

setACL({'::/0','0.0.0.0/0'})

This section sets up the recursive pool of servers to use for querying.

• newServer() – sets the parent recursive DNS servers to balance between. In the above examples, we use two public ones – Google and Cloudflare. Can be your provider’s recursive or other public ones.
• recursivepc=newPacketCache() – sets up the details on the packet cache to improve performance and expire old entries.
• getPool():setCache() – links the recursive pool to the recursivepc packet cache defined before
• setACL() – needed to allow any incoming queries to hit the Netmask Group ACLs previously defined.