DNS Proxy

DNS proxy listens for incoming DNS requests on the local interface and resolves remote hosts using an external PHP script, through http proxy requests.

If you can't use VPN, UDP tunnels or other methods to resolve external names in your LAN, DNS proxy is a good and simple solution.

Building

For debian/ubuntu users:
apt-get install libcurl4-openssl-dev

then

make

Usage

dnsp -l 127.0.0.1 -h 10.0.0.2 -r 8080 -s http://www.andreafabrizi.it/nslookup.php

In this case, DNS proxy listens on port 53 (bind on 127.0.0.1) and sends the requests to external script through the 10.0.0.2:8080 proxy.

IMPORTANT: Please, don't use the script hosted on my server, it's only for testing purpose. Instead host the nslookup.php script on your own server or use a free hosting services. Thanks!

 dnsp 0.5
 usage: dnsp -l [local_host] -h [proxy_host] -r [proxy_port] -s [lookup_script]

 OPTIONS:
      -v  	 Enable DEBUG mode
      -p		 Local port
      -l		 Local host
      -r		 Proxy port
      -h		 Proxy host
      -u		 Proxy username (optional)
      -k		 Proxy password (optional)
      -s		 Lookup script URL

Testing

To test if DNS proxy is working correctly, first run the program as following (replace the placeholders with the correct proxy IP and port!):

dnsp -l 127.0.0.1 -h x.x.x.x -r nnnn -s http://www.andreafabrizi.it/nslookup.php

then, try to resolve an hostname using the dig command:

dig www.google.com @127.0.0.1

The result must be something like this:

; <<>> DiG 9.8.1-P1 <<>> www.google.com @127.0.0.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 29155
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

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

;; ANSWER SECTION:
www.google.com.		3600	IN	A	173.194.64.106

;; Query time: 325 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Fri May 17 11:52:08 2013
;; MSG SIZE  rcvd: 48

Changelog:

Version 0.5 - May 17 2013:

• Add proxy authentication support
• port option is now optional (default is 53)
• Fixed compilation error
• Minor bug fixes

Version 0.4 - November 16 2009:

• Now using libCurl for http requests
• Implemented concurrent DNS server
• Bug fixes
• Code clean

Version 0.1 - April 09 2009:

• Initial release