Hi, im want know how i can see if my dedicated server is vunerable to DDOS atacks or what vulnerabilitys have, and how i can install some fix that. i hope someone can help me
Try installing CSF with tight settings, mod_evasice/dos_evasive, and mod_limitipconn. This will help with most ddos, otherwise, a hardware firewall will be your best bet, if money is not a factor.
Because of the imperceptibility of DDOS, so far we haven't found an absolutely effective way to deal with DDOS. To us the most important is, increasing security awareness and improving network security.
Yes, that is the thing that really sucks about DDOS defense; There is only so much 'rate limiting' you can do before you block so many 'real' visitors that your business suffers. One of my sites had a DDOS two months ago and believe me I thought I had all the bases covered - everything from hardening apache (some say lighttpd handles ddos better - still researching), a hardened firewall, and two failovers. What saved my backside was a managed DDOS service. It was expensive, but it got the site online and generating revenue within an hour. SO - my advice would be to learn as much as you can, harden everything as far as you can, then develop a relationship with a good DDOS provider. You may only need them once a year, but they are worth it. ...until I can figure out all the things they do, then I will do it myself PS - If you are under an attack, it would not hurt to call up your host; sometimes they can help. If you have your site/server already doing all it can (security-wise), they may have some options/services available. Maybe just opening up some extra bandwidth for 24 hours might do the trick unless you have a BIG attack going.
I get DDOS attacked a few times per week. Dealing with them mainly requires a knowledgable admin. Since DDOS attacks can take on many forms you have to be diligent in your defenses. I have had up to 90mbps attacks that were sustained for days but I managed to stay online. IMHO any defense that's at the service level (Apache) is crap. Yes they help against the normal DOS attack and it can't hurt to deploy those methods but it's not nearly as effective as a firewall with strong rulesets. A good admin can spot the pattern of an attack and work to firewall it. I do crazy stuff like blocking entire countries or maybe just whitelisting a few. Unfortunately the truth is that there is no such thing imho as 100% DDOS protection. Giant sites like Twitter get taken down let alone small/medium sites that don't have the defense resources of larger companies. I run a hacker forum (please don't judge me by what members do) and you can go there for lots of info on DDOS attacks including prevention. Sometimes knowing how a DDOS attack is formed is the best start to helping stop one. DDOS attacks are really just patterns or puzzles that you need to figure out and solve.