diff --git a/inc/config.php b/inc/config.php
index de4760fd..d57f8305 100644
--- a/inc/config.php
+++ b/inc/config.php
@@ -23,7 +23,8 @@
 		'spam' => Array(),
 		'flood_filters' => Array(),
 		'wordfilters' => Array(),
-		'custom_capcode' => Array()
+		'custom_capcode' => Array(),
+		'dnsbl' => Array()
 	);
 	// Database stuff
 	
@@ -124,7 +125,7 @@
 	$config['error']['unoriginal']		= 'Unoriginal content!';
 	$config['error']['muted']			= 'Unoriginal content! You have been muted for %d seconds.';
 	$config['error']['youaremuted']		= 'You are muted! Expires in %d seconds.';
-	$config['error']['tor']				= 'Hmm… That looks like a Tor exit node.';
+	$config['error']['dnsbl']			= 'Your IP address is listed in %s.';
 	$config['error']['toomanylinks']	= 'Too many links; flood detected.';
 	$config['error']['toomanycites']	= 'Too many cites; post discarded.';
 	$config['error']['toomanycross']	= 'Too many cross-board links; post discarded.';
@@ -187,7 +188,9 @@
 	// sha1_file, md5_file, etc.
 	$config['file_hash']	= 'sha1_file';
 	
-	$config['block_tor']	= true;
+	// DNS blacklists (DNSBL) http://www.dnsbl.info/dnsbl-list.php
+	$config['dnsbl'][] = 'tor.dnsbl.sectoor.de'; // Tor exit nodes
+	
 	// Typically spambots try to post a lot of links. Refuse a post with X standalone links?
 	$config['max_links']	= 20;
 	// Maximum number of cites per post (protects against abuse)
diff --git a/inc/functions.php b/inc/functions.php
index dd91fe62..cc12ce78 100644
--- a/inc/functions.php
+++ b/inc/functions.php
@@ -991,34 +991,31 @@
 		)));
 	}
 	
-	function isDNSBL() {
-		$dns_black_lists = file('./dnsbl.txt', FILE_IGNORE_NEW_LINES);
+	function checkDNSBL() {
+		global $config;
 		
-		// Reverse the IP
-		$rev_ip = implode(array_reverse(explode('.', $_SERVER['REMOTE_ADDR'])), '.');
-		$response = array();
-		foreach ($dns_black_lists as $dns_black_list) {
-			$response = (gethostbynamel($rev_ip . '.' . $dns_black_list));
-			if(!empty($response))
-				return true;
-		}
+		if(isIPv6())
+			return; // No IPv6 support yet.
 		
-		return false;
+		if(!isset($_SERVER['REMOTE_ADDR']))
+			return; // Fix your web server configuration
+		
+		// Reverse IP
+		$ip = ReverseIPOctets($_SERVER['REMOTE_ADDR']);
+		
+		foreach($config['dnsbl'] as &$blacklist) {
+			$lookup = $ip . '.' . $blacklist;
+			if(gethostbyname($lookup) != $lookup) {
+				// On NXDOMAIN (meaning it's not in the blacklist), gethostbyname() returns the host unchanged.
+				error(sprintf($config['error']['dnsbl'], $blacklist));
+			}
+		}
 	}
 	
 	function isIPv6() {
 		return strstr($_SERVER['REMOTE_ADDR'], ':') !== false;
 	}
 	
-	function isTor() {
-		if(isIPv6())
-			return false; // Tor does not support IPv6
-		
-		return gethostbyname(
-				ReverseIPOctets($_SERVER['REMOTE_ADDR']) . '.' . $_SERVER['SERVER_PORT'] . '.' . ReverseIPOctets($_SERVER['SERVER_ADDR']) . '.ip-port.exitlist.torproject.org'
-			) == '127.0.0.2';
-	}
-			
 	function ReverseIPOctets($ip) {
 		$ipoc = explode('.', $ip);
 		return $ipoc[3] . '.' . $ipoc[2] . '.' . $ipoc[1] . '.' . $ipoc[0];
diff --git a/post.php b/post.php
index 87ddf21b..478f157b 100644
--- a/post.php
+++ b/post.php
@@ -41,8 +41,7 @@
 		// Check if banned
 		checkBan();
 		
-		if($config['block_tor'] && isTor())
-			error($config['error']['tor']);
+		checkDNSBL();
 			
 		// Check if board exists
 		if(!openBoard($_POST['board']))
@@ -102,8 +101,7 @@
 		// Check if banned
 		checkBan();
 		
-		if($config['block_tor'] && isTor())
-			error($config['error']['tor']);
+		checkDNSBL();
 			
 		// Check if board exists
 		if(!openBoard($_POST['board']))
@@ -179,8 +177,7 @@
 		// Check if banned
 		checkBan();
 		
-		if($config['block_tor'] && isTor())
-			error($config['error']['tor']);
+		checkDNSBL();
 			
 		// Check if board exists
 		if(!openBoard($post['board']))