I want give rights for the maint user to execute the "ping" command. Currently root user can execute the "ping" command, but the maint user is not able to execute the command.
what I am looking for is the file where I have to do the changes...!
You could set the privileges for the ping executable.
Type: which ping
Then use the ls command, with the path you got as output from the previous command, to see ping's current privileges: ls -l /path_to/ping
Check the man page for chmod and commit your existing ping privileges to memory.
We really need more information than you've provided. What's the OS? How are you configuring a "maint user"? Is there a special environment? Are you using ACL's? Sun's Security tool (name escapes me but like Sudo)? Sudo 
?
Insufficient Data.
Carl