Given a host name and the port, checks if the connection can be established

ccheck.c

/**
 *
 * ccheck => 'C'onnection Check.
 *
 * Given a host name and the port, checks if the connection can be established.
 * Useful for 'secured' hosts where 'telnet' is not installed, but there is a need to check a connection.
 *
 **/

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <errno.h>

int main( int argc, char *argv[] ) {

    struct addrinfo hints, *res, *p;
    int status, sockfd;
    char ipstr[INET6_ADDRSTRLEN];

    if ( argc != 3 ) {
        fprintf( stderr,"usage: connectip hostname port\n" );
        return 1;
    }

    memset( &hints, 0, sizeof hints );
    hints.ai_family = AF_UNSPEC;        // AF_INET or AF_INET6 to force version
    hints.ai_socktype = SOCK_STREAM;

    if ( ( status = getaddrinfo( argv[1], argv[2], &hints, &res ) ) != 0 ) {
        fprintf( stderr, "getaddrinfo: %s\n", gai_strerror( status ) );
        return 2;
    }

    printf( "Connection to..." );

    for( p = res; p != NULL; p = p->ai_next ) {
        void *addr;
        char *ipver;

        // get the pointer to the address itself,
        // different fields in IPv4 and IPv6:
        if ( p->ai_family == AF_INET ) { // IPv4
                struct sockaddr_in *ipv4 = ( struct sockaddr_in * ) p->ai_addr;
                addr = &( ipv4->sin_addr );
                ipver = "IPv4";
        } else { // IPv6
                struct sockaddr_in6 *ipv6 = ( struct sockaddr_in6 * ) p->ai_addr;
                addr = &( ipv6->sin6_addr );
                ipver = "IPv6";
        }

        // convert the IP to a string and print it:
        inet_ntop( p->ai_family, addr, ipstr, sizeof ipstr );
        printf( "  %s: %s\n", ipver, ipstr );
    }

    sockfd = socket( res->ai_family, res->ai_socktype, res->ai_protocol );

    if( connect( sockfd, res->ai_addr, res->ai_addrlen ) == -1 ) {
        printf( "Connection error\n" );
        perror( argv[0] );
        return errno;
    }
    else
        printf( "Connection successful\n" );

    close( sockfd );
    freeaddrinfo( res ); // free the linked list

    return 0;
}

Makefile

CFLAGS=-Wall -g

all:	clean
		make ccheck

clean:
		rm -f ccheck
		rm -rf ccheck.dSYM