evangwt / chinadns

Protect yourself against DNS poisoning in China.

ChinaDNS

Traditional way to bypass DNS poisoning is to send all queries to a foreign DNS server via VPN. However some Chinese websites will get bad results if they have CDNs outside the country.

The second way is to maintain a list of domains of which you want to resolve from local DNS or foreign DNS. This list changes too often, taking too much effort to maintain.

ChinaDNS automatically queries local DNS servers to resolve Chinese domains and queries foreign DNS servers to resolve foreign domains. It is smart enough to work only with a Chinese IP range file, which doesn't change often.

In order to bypass IP blocking, you SHOULD use VPN software like ShadowVPN.

Install

• Linux / Unix

  Download a release.

    ./configure && make
    src/chinadns -m -c chnroute.txt
  

• OpenWRT

  • Download precompiled for OpenWRT trunk and CPU: ar71xx, brcm63xx, brcm47xx, ramips_24kec. Open an issue if you think your CPU is a popular one but not listed here.

  • If you use other CPU or other OpenWRT versions, build yourself: cd into SDK root, then

      pushd package
      git clone https://github.com/clowwindy/ChinaDNS.git
      popd
      make menuconfig # select Network/ChinaDNS
      make -j
      make V=99 package/ChinaDNS/openwrt/compile
    

• Tomoto

  • Download Tomato toolchain, build by yourself.

  • Uncompress the downloaded file to ~/.

  • Copy the brcm directory under ~/WRT54GL-US_v4.30.11_11/tools/ to /opt, then

      export PATH=/opt/brcm/hndtools-mipsel-uclibc/bin/:/opt/brcm/hndtools-mipsel-linux/bin/:$PATH
      git clone https://github.com/clowwindy/ChinaDNS.git
      cd ChinaDNS
      ./autogen.sh && ./configure --host=mipsel-linux --enable-static && make
    

• Windows

  Download Python exe version.

Usage

• Linux / Unix Recommand using with option "-m" (DNS pointer mutation method) Run sudo chinadns -m -c chnroute.txt on your local machine. ChinaDNS creates a UDP DNS Server at 0.0.0.0:53.

• OpenWRT

    opkg install ChinaDNS_1.x.x_ar71xx.ipk
    /etc/init.d/chinadns start
    /etc/init.d/chinadns enable
  

  Invoke the "enable" command to run the initscript on boot

  (Optional) We strongly recommend you to set ChinaDNS as a upstream DNS server for dnsmasq instead of using ChinaDNS directly:

  1. Run /etc/init.d/chinadns stop

  2. Remove the 2 lines containing iptables in /etc/init.d/chinadns.

  3. Update /etc/dnsmasq.conf to use only 127.0.0.1#5353:

      no-resolv
      server=127.0.0.1#5353
     

  4. Restart chinadns and dnsmasq

Test if it works correctly:

$ dig @192.168.1.1 www.youtube.com -p5353
; <<>> DiG 9.8.3-P1 <<>> @127.0.0.1 www.google.com -p5353
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29845
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.youtube.com.		IN	A

;; ANSWER SECTION:
www.youtube.com.	21569	IN	CNAME	youtube-ui.l.google.com.
youtube-ui.l.google.com. 269	IN	A	216.58.220.174

;; Query time: 74 msec
;; SERVER: 127.0.0.1#5353(127.0.0.1)
;; WHEN: Fri Jan 30 18:37:57 2015
;; MSG SIZE  rcvd: 83

Currently ChinaDNS only supports UDP. Builtin OpenWRT init script works with dnsmasq, which handles TCP. If you use it directly without dnsmasq, you need to add a redirect rule for TCP:

iptables -t nat -A PREROUTING -p tcp --dport 53 -j DNAT --to-destination 8.8.8.8:53

Advanced

usage: chinadns [-h] [-l IPLIST_FILE] [-b BIND_ADDR] [-p BIND_PORT]
       [-c CHNROUTE_FILE] [-s DNS] [-v]
Forward DNS requests.

-h, --help            show this help message and exit
-l IPLIST_FILE        path to ip blacklist file
-c CHNROUTE_FILE      path to china route file
                      if not specified, CHNRoute will be turned off
-d                    enable bi-directional CHNRoute filter
-y                    delay time for suspects, default: 0.3
-b BIND_ADDR          address that listens, default: 127.0.0.1
-p BIND_PORT          port that listens, default: 53
-s DNS                DNS servers to use, default:
                      114.114.114.114,208.67.222.222:443,8.8.8.8
-m                    Using DNS compression pointer mutation
                      (backlist and delaying would be disabled)
-v                    verbose logging

About chnroute

You can generate latest chnroute.txt using this command:

curl 'http://ftp.apnic.net/apnic/stats/apnic/delegated-apnic-latest' | grep ipv4 | grep CN | awk -F\| '{ printf("%s/%d\n", $4, 32-log($5)/log(2)) }' > chnroute.txt

License

Copyright (C) 2015 clowwindy

This program 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.

This program 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/.

Bugs and Issues

Please visit Issue Tracker

Mailing list: http://groups.google.com/group/shadowsocks