UDP Port 3437

I have been seeing traffic like this on my firewall more and more. Does anyone know what it is?

99. 101103 rule 19/0(match): block in on le0: 4.234.24.139.34247 > 192.168.100.7.3437: UDP, length 31
44. 809854 rule 19/0(match): block in on le0: 24.197.158.193.36787 > 192.168.100.7.3437: UDP, length 35
19. 922285 rule 19/0(match): block in on le0: 219.58.194.9.6346 > 192.168.100.7.3437: UDP, length 31
603. 012552 rule 19/0(match): block in on le0: 75.83.84.151.24363 > 192.168.100.7.3437: UDP, length 31
509. 641906 rule 19/0(match): block in on le0: 124.184.98.120.25705 > 192.168.100.7.3437: UDP, length 35

Listen for http connections with C

#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <signal.h>
#include  <arpa/inet.h>
#include <time.h>

#define PORT 30000
#define MAXBUFF 1024

int wwwsock;

void myError(char *err) {
    perror(err);
    exit(1);
}

void catchSig(int sig) {
  close(wwwsock);
 exit(0);
}

int main(int argc, char *argv[]) {
 char timebuff[250];

 char *buffer;
 char *req;
 int clientAddr, newConnection, size;
 int optval=1;

 time_t curtime;
 struct sockaddr_in serv_addr, cli_addr;
 
  (void)signal(SIGINT, catchSig);
 wwwsock = socket(AF_INET, SOCK_STREAM, 0);

 
 if(wwwsock<0) 
  myError("Socket Failed\n");
 

 memset(&serv_addr,'\0',sizeof(serv_addr));
 serv_addr.sin_family = AF_INET;
 serv_addr.sin_addr.s_addr = INADDR_ANY;
 serv_addr.sin_port = htons(PORT);

 setsockopt(wwwsock, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof optval);
 
 if (bind(wwwsock,(struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0) {

  char error[30];
  sprintf(error,"ERROR binding to port %d",PORT);
  myError(error);
 }

 
 listen(wwwsock,5);
 clientAddr=sizeof(struct sockaddr_in);
 buffer=malloc(MAXBUFF); 

 req=malloc(MAXBUFF);
 while(1) {
  newConnection=accept(wwwsock,(struct sockaddr *) &cli_addr,(socklen_t *)&clientAddr);

  memset(buffer,'\0',sizeof(buffer));
  
  if(recv(newConnection,buffer,MAXBUFF,0) > 0) {

  
   if(strstr(buffer,"\n")) {
    size=(strlen(buffer)-strlen(strstr(buffer,"\n")));

   }
   else
    size=0;
   
   if(size>0 && size<MAXBUFF) {

    curtime=time(NULL);
    strftime(timebuff,sizeof(timebuff),"%c",localtime (&curtime));
    strncpy(req,buffer,size+1);
    printf("%s Client %s Requested %s",timebuff,inet_ntoa(cli_addr.sin_addr),req);

   }
   
   send(newConnection,"HTTP/1.1 404 Not Found\r\nConnection: close\r\n\r\n",22,0);

   close(newConnection);
  }
 } 
 close(wwwsock);
 return 0; 

}

Using Ports within a jail

To cut down on hard drive space use it's a good idea to use the ports directory from the main system in each jail. To secure it the best idea is to mount /usr/ports read only. The problem with having /usr/ports read only is the source can not be saved in /usr/ports/distfiles. To fix this we need to tell make to save the files elsewhere.

First edit /etc/fstab and add
/usr/ports/PATH_TO_JAIL     /usr/ports     nullfs     ro     0     0

After remount file systems
mount -a

From within the jail create the dir /var/distfile and add
DISTDIR=/var/distfile and WRKDIRPREFIX=/var/distfiles to /etc/make.conf

All the files shoud besave in /var/distfile from now on.