Can't seem to receive UDP packets

I'm trying to get a UDP server working and just can't seem to get it to read in any UDP packets. I can see the packet coming in on the correct interface and port from tcpdump, but my program never logs that it got the data.

I just keep getting a log showing that my recvfrom timed out. I'm pretty sure I'm setting everything up correctly. Anyone have an idea as to what I'm missing?

Code:

---

int create_listen_socket()
{
        struct sockaddr_in si_me;
        int sock_fd;
        struct ifaddrs * ifAddrStruct=NULL;
        struct ifaddrs * ifa=NULL;
        void * tmpAddrPtr=NULL;
        struct timeval tv;

        memset((char *) &si_me, 0, sizeof(si_me));
        if ((sock_fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1)
        {
                printf("Create socket error %d.\n", errno);
                return -1;
        }

        tv.tv_sec = 5;
        tv.tv_usec = 0;
        if (setsockopt(sock_fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) < 0)
        {
                printf("setsockopt error %d.\n", errno);
                return -1;
        }

        getifaddrs(&ifAddrStruct);
        for (ifa = ifAddrStruct; ifa != NULL; ifa = ifa->ifa_next)
        {
                if ((ifa->ifa_addr->sa_family == AF_INET) &&
                                (strcmp(ifa->ifa_name, "eth0") == 0))
                { // check it is IP4
                        // is a valid IP4 Address
                        si_me.sin_addr.s_addr = ((struct sockaddr_in *) ifa->ifa_addr)->sin_addr.s_addr;

                        tmpAddrPtr=&((struct sockaddr_in *)ifa->ifa_addr)->sin_addr;
                        char addressBuffer[INET_ADDRSTRLEN];
                        inet_ntop(AF_INET, tmpAddrPtr, addressBuffer, INET_ADDRSTRLEN);
                        printf("%s IP Address %s\n", ifa->ifa_name, addressBuffer);
                        break;
                }
        }
        if (ifAddrStruct != NULL)
        {
                freeifaddrs(ifAddrStruct);
        }

        si_me.sin_family = AF_INET;
        si_me.sin_port = htons(LISTEN_PORT);
        if (bind(sock_fd, (struct sockaddr*) &si_me, sizeof(si_me)) == -1)
        {
                printf("Bind error %d.\n", errno);
                return -1;
        }

        return sock_fd;
}

void * listen_thread(void * args)
{
        char buf[BUFLEN];
        struct sockaddr_in si_other;
        int slen = sizeof(si_other);
        int num_bytes;
        int sock_fd = create_listen_socket();

        while(sock_fd > 0 &&
                        running)
        {
                num_bytes = recvfrom(sock_fd, (void*) buf, BUFLEN, 0, (struct sockaddr*) &si_other, (socklen_t *) &slen);
                if(num_bytes > 0)
                {
                        printf("Got data.\n");
                }
                printf("Got %d bytes. errno %d\n", num_bytes, errno);
        }

        return 0;
}

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Mods, close this thread if you can. I was running this on a fresh install of CentOS and forgot to turn my firewall off! I didn't realize tcpdump could pick up packets before the firewall.