IP and Time in Flat File Database for Spam Protection

section31

Hi, I'm trying to make a spam protection script to prevent people from posting more than once per X minutes.

I've done this before, and it was extremely easy using a mysql database. But I'm trying to implement this into a flat file database just as a quick alternative.

The flat file database will look like this. It will have the ip and unix time stamp on each line deliminated by a |

Now what would be the most efficient way to check if the ip exists in the file and the time is older than X seconds.

Anyone have any ideas. Pseudo code would be fine if you don't have a similar function already made out.

planetsim

Im not going to give you code I think you should make an attempt at least, its not hard.

Functions Id use would probably be explode, list, file, foreach

anthill

I agree with planetsim, at least have a go!!! Post your code in here if you get stuck.

section31

sorry for the late reply..I didn't receive any email notification...

how about this...works fine, but don't know if anyone can think of a better way...I certainly thought of like 3-4 diff ways of doing it, but this seemed the best.

$ip = $_SERVER['REMOTE_ADDR'];
$ctime = time();
$db = 'db.txt';

/*This function will return true if ip was posted here in the past 60 seconds */
function checkIP()
{
   global $ip, $ctime, $db;
   $match = false;

   $lines = file($db);
   $handle = fopen($db,"w") ;

   foreach($lines as $line)
   {
      list($thisip, $thistime ) = explode( "|" , $line );

  if ( $thistime > $ctime-60 ) {
     if ( $thisip == $ip ) $match = true;
     fwrite($handle, "{$thisip}|{$thistime}\n");
  }
   }
   fclose($handle);

   return $match;
}

Roger_Ramjet

If it is spam protection you are after then forget using IP: there are several threads around that explain why IP is no guarantee of identity. True spammers will already be morphing source IPs in their robots and agents. Plus, any users using the same ISP are likely to be surfing through a proxy so they will appear to your script as having the same IP.

section31

Originally posted by Roger Ramjet
If it is spam protection you are after then forget using IP: there are several threads around that explain why IP is no guarantee of identity. True spammers will already be morphing source IPs in their robots and agents. Plus, any users using the same ISP are likely to be surfing through a proxy so they will appear to your script as having the same IP.

You think you can find those threads for me...I didn't find much after doing a few searches.
As far as preventing users from behind a proxy from posting...I could always use their forwarded ip from the header, but someone could always spoof that...so i prefer to use the regular ip. Besides, its only a temporary ban from posting for 60 seconds. Wouldn't do much harm to a site that isn't very active.

I'm still interested in finding other ways to prevent spamming?

rehfeld

if your just doing this to deter spam, i think youve got the right idea.

you could also set cookies but i think using ips would be more effective at stopping spammers from posting more than once every 60 secs or whatever.

the chances of 2 diff users with the same ip, trying to post within 60 secs of each other is very small. i think your idea is good for your purposes.

as far as efficiency goes, it looks pretty good to me. your cleaning up all old entries everytime you check, which is a good idea.

as far as more ways to fight spam, i think this discusses it decently
http://www.ilovejackdaniels.com/spam/stop-comment-spam/

section31

hm...I just noticed that I should lock the files in my function above. I'm a bit confused about the flock function... Especially about the difference between a shared lock and an exclusive lock. What happens if you use an exclusive lock, and 2 people try to read/write the file at the same time?