Simple forwarding+caching DNS server that works with upstreams over TCP

A tiny DNS server with the ability to forward your DNS requests to upper DNS servers using TCP proto:

• works like a transport proxy UDP -> TCP (requests coming to DNS server via UDP converts to queries over TCP)
• multi-threading (the main reason why golang used)
• cache-in-memory
• periodic garbage collector (removes outdated records by TTL)
• configuration file support

                                         dns 1
                                       /
DNS                                   /
clients ---UDP---> dns2tcp server---TCP--------> dns 2
                                      \
                                       \
                                        ...
                                          \ dns N

cd /etc
git clone https://github.com/denisix/dns2tcp

cd dns2tcp
go run dns2tcp.go

• bind 127.0.0.1:53 - instructs server to listed on IP 127.0.0.1, port 53
• ns 1.1.1.1:53 - send TCP DNS queries to upstream at 1.1.1.1 (CloudFlare in this case)
• ttl-absent 3600 - how long cache absent records, their TTL in secs
• timeout 100 - 100 msec timeout to wait for reply
• retry 30 - retries before we gen the content
• gc-interval 1800 - 30 min (1800 sec) interval for garbage collector runs

go build dns2tcp.go
./dns2tcp