flbuddymooreiv / mydns

Make a program think a host is any IP address you want

mydns

This program will change the IP address for a given host in a network program. This can be done by modifying /etc/hosts but if you do not have system administration privileges, you can use this method by utilizing the LD_PRELOAD environment variable for the loader.

It will replace the following library calls:

• gethostbyname2
• gethostbyaddr
• getaddrinfo

Build the sources

gcc -o mydns.so -ldl -shared -fPIC mydns.c

gcc -o test test.c

Demo:

user@host:~/dev/mydns$ ./test
74.125.198.147
74.125.198.99
74.125.198.103
74.125.198.104
74.125.198.105
74.125.198.106
0.0.0.0

user@host:~/dev/mydns$ LD_PRELOAD=/path/to/compiled/mydns.so ./test
123.123.123.123

Of course the hostname and the IP address could be specified in a config file, or command line parameters, but for now, simply change the strings in mydns.c to fit your needs.