Hey, I know that there are different kinds of DDoS (Syn, HTTP etc.), is there anyway to protect his Site from DDoS if I have a Webspace (no Vserver, Rootserver). Is there maybe any Script or sth like that ? And does a htaccess helps against DDoS ?
Depends on the type of attack, if you knew about DDoS you would know that there is different techniques to handling different types of dDoS
even there are firewalls which could block dos. checkout apf and configserver. If you want maximum dos protection, you have to go for harware.
Software protection is only so good. A full DDos attack requires hardware. If you think about it, if the attackers are allowed to get to the server itself, then the server loads will rise, even if they are banned IP's, as the server still needs to be able to connect to determine the IP address. There are some great suggestions above for software protection.
You could also go with a pay as you go service, depending on the size of the botnet this might be the best way. Solutions such as those provided by ddos protection companys like dosarrest can protect your server remotely. They have various features you can take advantage of as well. If you have any idea of the size of the attack (if not talk to your ISP) you might have a better idea of what type of solution best fits your needs. DDOS attacks can be never ending if someone really wants to cause harm, and most of these botnet's are rented and as such someone could potentially just rent a bigger and better botnet. Security Professionals have their hands full trying new defensive techniques to match changes in botnet behavior. Software on your webserver may only help defend you from smaller attacks. otherwise an attack large enough will just consume your entire bandwidth to your server, and your ISP will probobly end up null routing your IP address. Good Luck with the battle.
Blocking DDoS attacks works to a point depending on server config/bandwidth and more. consider the following resource as a very helpful guide. http://r00tsecurity.org/forums/index.php?showtopic=19607
for a small size of attack, software based firewall with a proper server configuration will be enough. But with a large-scale attack, you will need a hardware based firewall, or even a spare server and huge bandwidth allocation to mitigate the attack. For this kind of attack, you should seek for a company who specialized in dDoS mitigation service, like blockdos or ddoswiz, just google them.
If the DDoS is large enough, then the firewall will not be able to cope and will in all intents and purposes collapse. Dosarrest are a very good service and mean you don't need to change your hosts.