CrappyDNS

CrappyDNS is a DNS repeater based on libuv, written in C++11, provides enhanced DNS resolution.

How it works

To use CrappyDNS, you need to provide a healthy DNS server list, a polluted DNS server list and a trusted net list.

Each DNS server list is a comma separated ip list, support optional tcp:// prefix to issue a TCP connection and :port suffix to connect to different port number other than the default port 53.

The trusted net list is a CIDR blocks list, with one CIDR blocks per line. In many cases, the CIDR blocks list may contains tons of duplicated or mergeable items, so CrappyDNS provides -o options to merge them as it possible.

For each DNS query, CrappyDNS will forward it to each DNS server in two lists. CrappyDNS prefer to use the result returned by polluted DNS server when the result is in trusted net list, and in opposite, it will prefer to use the result returned by healthy DNS server when the result is not in trusted net list.

CrappyDNS also supports an enhanced hosts file format, which enables you to designate a special DNS server (or resolution result) for specific domain, you may refer to hosts file in this repo to see more details.

Build

Linux / Unix

You should have libuv installed first, then

$ ./autogen.sh
$ ./configure
$ make

OpenWrt

1. Follow the instruction to install OpenWrt SDK
2. Clone this repo into package folder under SDK root directory
3. Run make menuconfig under SDK root directory and select Network/crappydns
4. Run make to start build process

Usage

crappydns [-l LISTEN_ADDR] [-p LISTEN_PORT] [-t TIMEOUT_IN_MS]
          [-b POISONED_DNS_LIST] [-g HEALTHY_DNS_LIST] [-v] [-V] [-h]
          [-n TRUSTED_NET_PATH] [-o TRUSTED_NET_PATH] [-a USER]
A crappy DNS repeater

Options:
-g, --good-dns <dns>	 Comma seperated healthy remote DNS server list,
			 DNS address schema: [(udp|tcp)://]i.p.v.4[:port]
			 Proctol default to udp, port default to 53
-b, --bad-dns <dns>	 Comma seperated poisoned remote DNS server list.
-s, --hosts <file>	 Path to hosts file
-n, --trusted-net <file> Path to the file contains trusted net list
-o, --optimize <file>	 Optimize trusted net list, write to stdout and exit
[-p, --port <port>]	 Port number of your local server, default to 53
[-l, --listen <addr>]	 Listen address of your local server,
			 default to 127.0.0.1
[-t, --timeout <msec>]	 Timeout for each session, default to 3000
[-a, --run-as <user>]	 Run as another user
[-v, --version]		 Print version and exit
[-V, --verbose]		 Verbose logging
[-h, --help]		 Print this message

License

CrappyDNS is licensed under GNU General Public License Version 3.

Copyright (C) 2019 Sunny

CrappyDNS is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

CrappyDNS is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.