Hi,

well sometimes DBAs and sysadmin need to check if a particular port is "open" on the corporate firewall

--i.e. *Grid Control* Will the communication between OMS and a management agent work? --

One solution well consist on deploying the piece of software in question, start it and just check if everything works fine, however i find more classy trying to get that information before

There are several tools for doing so --i.e. nmap *like Trinity on The Matrix*, but just found a nice piece of code for establishing a socket on a parameter passed port.

After running the program doing a telnet from the client machine  will be a walk in the park

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

int main(int argc, char *argv[])
{
     int sockfd, newsockfd, portno, clilen;
     char buffer[256];
     struct sockaddr_in serv_addr, cli_addr;
     int n;
     if (argc < 2) {
         fprintf(stderr,"ERROR: A port must be provided. Aborting ...\n");
         return 1;
     }
     sockfd = socket(AF_INET, SOCK_STREAM, 0);
     if (sockfd < 0)
         {
        fprintf("ERROR: Unable to open socket. Aborting ...\n");
        return 1;
      }
     portno = atoi(argv[1]);
     serv_addr.sin_family = AF_INET;
     serv_addr.sin_addr.s_addr = INADDR_ANY;
     serv_addr.sin_port = htons(portno);
     if (bind(sockfd, (struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)
         {
              fprintf("ERROR: Unable to bind socket. Aborting ...\n");
              return 1;
      }
     listen(sockfd,5);
     clilen = sizeof(cli_addr);
     newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr,&clilen);
     if (newsockfd < 0)
         {
          fprintf("ERROR: Unable to accept connection. Aborting...\n");
          return 1;
       }
     return 0;
}

Of course, you can still ask to the network guy if the port is open or not
Hope it helps
L