mdns-proxy is a DNS proxy that accepts DNS queries and proxies them to Avahi for a multicast DNS lookup.

When you're on a LAN, multicast DNS is a handy way to find machines, and generally alleviates the need for assigning static IPs to local machines. But when connecting to that same LAN via a VPN, multicast DNS often isn't available, and suddenly you have to remember a bunch of IPs if you want to access the servers there.

mdns-proxy is designed to act as an authoritative DNS server that responds to domain X (e.g. ".vpn") and proxies to the multicast DNS "Avahi" daemon using multicast domain Y (e.g. ".local").

On your local DNS server, you can manually delegate domain X to the mdns-proxy server. Now, if you query e.g. "myserver.vpn", mdns-proxy will receive your query and resolve it using Avahi as e.g. "myserver.local". In essence, domain X becomes a remote mirror of multicast domain Y, even though you have no way to do normal mDNS to the LAN over your VPN link.

You'll need to edit the constants at the top to reflect your network configuration. Then just run the proxy.

If you're using a caching DNS proxy like djbdns's "dnscache", you'll probably need to listen on the standard DNS port (53), which requires root privileges. If run as root, mdns-proxy will change to the "nobody" user after creating the UDP socket. (Alternatively, you can use NAT rules to allow you to listen on another port.)

mdns-proxy is released under the standard 2-clause BSD license. See COPYING for details.

• IPv6 support (if the internet ever finally switches)