Hi,
I am trying to write a program, to find the open port on any system. Rightnow, my programm is working fine on the same system ip.

Now, i want to enhanced it to get any IP address and perform the task.
Problem is that, i have only IP address, like "111:111:111:111".
From this how to get the struct hostent *he;
I have tried with the following code

//he = gethostbyname( compName );
unsigned int addr = inet_addr("111:111:111:111");
hostent *he = gethostbyaddr((char *) &addr, 4, AF_INET);
But getgostbyaddress is returning NULL.
Any body help me.

111:111:111:111 is not a valid IPv4 address. Try 127.0.0.1 instead, for a start. (That's localhost so it will connect to your own box anyway.)

That IP addess is as exapmle. i am giving my IP address which given by ipconfig command. Assume it 72.14.253.125 .

Seems you should put the return value from inet_addr in addr.s_addr.

./ettercap-0.5.0/src/ec_inet.c - Google Code Search

I tried the code fromm link.
struct in_addr addr;

addr.s_addr = inet_addr( "121.243.2231.133" );
he = gethostbyaddr((char *)&addr, sizeof(struct in_addr), AF_INET);

Again he is NULL>\.