Skip to content

Setting for high load and prevent DDoS (sysctl, iptables, crowdsec or other)

Security
  • Hello,

    I am looking for ways to make the weavers that we top the world a little more secure via web servers etc…

    I saw this article which allows to best configure the kernel:

    https://www.thegeekdiary.com/sysctl-setting-for-high-load-and-prevent-ddos/

    Do you think this config is valid @phenomlab or would you have others to offer?


    I know Iptables can be a good tool too. I saw this article about it (but ideally for centOS, maybe it’s good for ubuntu server ?):

    https://javapipe.com/blog/iptables-ddos-protection/


    Using Virtualmin, if you have tricks for firewallD (installed by default), I’m interested.

    Besides, FirewallD is based on its own app or on Iptables or something else like ufw?

    I would be curious to know because I use it to open certain ports.

    In short, a topic to list all the tips for securing a server and in this case a server without of course disturbing users accessing the web server and in this case, for me it is nodebb

    cya

  • @DownPW I’d steer well clear of modifying any kernel as detailed in the first post. There is so much that can go wrong here, it’ll take me a day to list all the possibilities. Whilst there’s nothing “wrong” with what is being suggested, it will affect the entire kernel and could present you with more issues than you set out to resolve.

    You have to remember that what works for one person won’t work for another because every environment is different.

    There’s also nothing fundamentally wrong with FirewallD either - it’s functional - albeit a bit basic, but it does the job very well and is simple to use. I’m curious to understand why you aren’t considering the Hetzner firewall as the first post as this makes much more sense to me in terms of handling DDoS traffic.

  • Ha why not.
    Because I just didn’t think of it lolol

    I know hetzner has DDOS protection which works well unlike some provides.

    It is active on my server but apart from 2 or 3 basic rules (SSH port, nodebb;) I don’t really see what to do with it

    in short if you have any advice to give to secure the best.

  • @DownPW 🙂 most of this really depends on your desired security model. In all cases with firewalls, less is always more, although it’s never as clear cut as that, and there are always bespoke ports you’ll need to open periodically.

    Heztner’s DDoS protection is superior, and I know they have invested a lot of time, effort, and money into making it extremely effective. However, if you consider that the largest ever DDoS attack hit Cloudflare at 71m rps (and they were able to deflect it), and each attack can last anywhere between 8-24 hours which really depends on how determined the attacker(s) is/are, you can never be fully prepared - nor can you trace it’s true origin.

    DDoS attacks by their nature (Distributed Denial of Service) are conducted by large numbers of devices whom have become part of a “bot army” - and in most cases, the owners of these devices are blissfully unaware that they have been attacked and are under command and control from a nefarious resource. Given that the attacks originate from multiple sources, this allows the real attacker to observe from a distance whilst concealing their own identity and origin in the process.

    If you consider the desired effect of DDoS, it is not an attempt to access ports that are typically closed, but to flood (and eventually overwhelm) the target (such as a website) with millions of requests per second in an attempt to force it offline. Victims of DDoS attacks are often financial services for example, with either extortion or financial gain being the primary objective - in other words, pay for the originator to stop the attack.

    It’s even possible to get DDoS as a service these days - with a credit card, a few clicks of a mouse and a target IP, you can have your own proxy campaign running in minutes which typically involves “booters” or “stressers” - see below for more

    https://heimdalsecurity.com/blog/ddos-as-a-service-attacks-what-are-they-and-how-do-they-work

    @DownPW said in Setting for high load and prevent DDoS (sysctl, iptables, crowdsec or other):

    in short if you have any advice to give to secure the best.

    It’s not just about DDos or firewalls. There are a number of vulnerabilities on all systems that if not patched, will expose that same system to exploit. One of my favourite online testers which does a lot more than most basic ones is below

    https://www.immuniweb.com/websec/

    I’d start with the findings reported here and use that to branch outwards.

  • phenomlabundefined phenomlab marked this topic as a regular topic on

  • 2 Votes
    4 Posts
    211 Views

    @Hari Ok, no issues. Keep me posted…

  • 12 Votes
    8 Posts
    274 Views

    @crazycells good question. Gmail being provided by Google is going to be one of the more secure by default out of the box, although you have to bear in mind that you can have the best security in the world, but that is easily diluted by user decision.

    Obviously, it makes sense to secure all cloud based services with at least 2fa protection, or better still, biometric if available, but email still remains vastly unprotected (unless enforced in the sense of 2fa, which I know Sendgrid do) because of user choice (in the sense that users will always go for the path of least resistance when it comes to security to make their lives easier). The ultimate side effect of taking this route is being vulnerable to credentials theft via phishing attacks and social engineering.

    The same principle would easily apply to Proton Mail, who also (from memory) do not enforce 2fa. Based on this fact, neither product is more secure than the other without one form of additional authentication at least being imposed.

    In terms of direct attack on the servers holding mail accounts themselves, this is a far less common type of attack these days as tricking the user is so much simpler than brute forcing a server where you are very likely to be detected by perimeter security (IDS / IPS etc).

  • 2 Votes
    3 Posts
    177 Views

    No response from OP so marking as closed

  • 4 Votes
    4 Posts
    207 Views

    @phenomlab said in TikTok fined £12.7m for misusing children’s data:

    Just another reason not to use TikTok. Zero privacy, Zero respect for privacy, and Zero controls in place.

    https://news.sky.com/story/tiktok-fined-12-7m-for-data-protection-breaches-12849702

    The quote from this article says it all

    TikTok should have known better. TikTok should have done better

    They should have, but didn’t. Clearly the same distinct lack of core values as Facebook. Profit first, privacy… well, maybe.

    Wow, that’s crazy! so glad I stayed away from it, rotten to the core.

  • 5 Votes
    6 Posts
    888 Views

    Missed out on this deal ? Windscribe offer a limited free version. More about that here
    https://sudonix.org/topic/13/which-product-is-the-best-for-vpn/164?_=1652206628456

  • 4 Votes
    3 Posts
    692 Views

    @phenomlab

    No they have a free and pro console instance.
    We can see alert with IP, Source AS, scenario attack etc…

    Installation on the NODEBB server without problems. Very good tools

    cf7e5a89-84f4-435b-82eb-434c0bfc895e-image.png
    cc82a10e-a1f1-4fd8-a433-7c9b2d31f254-image.png

    1b7147b0-37c6-4d87-b4f1-a0fe92e74afd-image.png

    7c21fc10-1825-48e1-a993-92b84455f074-image.png


    We can also do research on IPs via the crowdsec analyzer

    I believe it’s 500 per month in the Free version

    43bc8265-a57c-4439-829c-0bb8602d99b4-image.png

  • 1 Votes
    2 Posts
    266 Views

    @mike-jones Hi Mike,

    There are multiple answers to this, so I’m going to provide some of the most important ones here

    JS is a client side library, so you shouldn’t rely on it solely for validation. Any values collected by JS will need to be passed back to the PHP backend for processing, and will need to be fully sanitised first to ensure that your database is not exposed to SQL injection. In order to pass back those values into PHP, you’ll need to use something like

    <script> var myvalue = $('#id').val(); $(document).ready(function() { $.ajax({ type: "POST", url: "https://myserver/myfile.php?id=" + myvalue, success: function() { $("#targetdiv").load('myfile.php?id=myvalue #targetdiv', function() {}); }, //error: ajaxError }); return false; }); </script>

    Then collect that with PHP via a POST / GET request such as

    <?php $myvalue= $_GET['id']; echo "The value is " . $myvalue; ?>

    Of course, the above is a basic example, but is fully functional. Here, the risk level is low in the sense that you are not attempting to manipulate data, but simply request it. However, this in itself would still be vulnerable to SQL injection attack if the request is not sent as OOP (Object Orientated Programming). Here’s an example of how to get the data safely

    <?php function getid($theid) { global $db; $stmt = $db->prepare("SELECT *FROM data where id = ?"); $stmt->execute([$theid]); while ($result= $stmt->fetch(PDO::FETCH_ASSOC)){ $name = $result['name']; $address = $result['address']; $zip = $result['zip']; } return array( 'name' => $name, 'address' => $address, 'zip' => $zip ); } ?>

    Essentially, using the OOP method, we send placeholders rather than actual values. The job of the function is to check the request and automatically sanitise it to ensure we only return what is being asked for, and nothing else. This prevents typical injections such as “AND 1=1” which of course would land up returning everything which isn’t what you want at all for security reasons.

    When calling the function, you’d simply use

    <?php echo getid($myvalue); ?>

    @mike-jones said in Securing javascript -> PHP mysql calls on Website:

    i am pretty sure the user could just use the path to the php file and just type a web address into the search bar

    This is correct, although with no parameters, no data would be returned. You can actually prevent the PHP script from being called directly using something like

    <?php if(!defined('MyConst')) { die('Direct access not permitted'); } ?>

    then on the pages that you need to include it

    <?php define('MyConst', TRUE); ?>

    Obviously, access requests coming directly are not going via your chosen route, therefore, the connection will die because MyConst does not equal TRUE

    @mike-jones said in Securing javascript -> PHP mysql calls on Website:

    Would it be enough to just check if the number are a number 1-100 and if the drop down is one of the 5 specific words and then just not run the rest of the code if it doesn’t fit one of those perameters?

    In my view, no, as this will expose the PHP file to SQL injection attack without any server side checking.

    Hope this is of some use to start with. Happy to elaborate if you’d like.

  • 0 Votes
    1 Posts
    204 Views
    No one has replied