Different types of Attacks in Network security

Denial-of-Service (DoS) Attacks
A DoS attack focuses on disrupting the service to a network. Attackers send high volumes of data or traffic through the network until the network becomes overloaded and can no longer function.

Distributed-denial-of-service (DDoS) attack. This involves the attacker using multiple computers to send the traffic or data that will overload the system. In many instances, a person may not even realize that his or her computer has been hijacked and is contributing to the DDoS attack.

 An advanced persistent threat (APT) is a network attack in which an unauthorized person gains access to a network and stays there undetected for a long period of time. The intention of an APT attack is to steal data rather than to cause damage to the network or organization.

MiTM (Man in the middle) attacks
The man-in-the middle attack intercepts a communication between two systems. In this attack an hacker captures data from middle of transmission and changes it, then send it again to the destination. Receiving person thinks that this message came from original source and reply back 

Brute force attack is a trial and error method used by application programs to decode encrypted data such as passwords or PIN .Brute force attacks may be used by criminals to crack encrypted data, or by security analysts to test an organization's network security. A brute force attack may also be referred to as brute force cracking.

Spoof attack
In this kind of attack an hacker changes the sources address of packet so receiver assumes that packet comes from someone else. This technique is typically used to bypass the firewall rules.

Ping sweep attack
In this attack an attacker pings all possible IP addresses on a subnet to find out which hosts are up. Once he finds an up system, he tries to scan the listening ports. From listing ports he can learn about the type of services running on that system. Once he figures out the services, he can try to exploit the vulnerabilities associated with those services.

Phishing Attack
In this attack an hacker creates fake email address or website which looks like a reputed mail address or popular site. These emails contain convincing message, some time with a link that leads to a fake site. This fake site looks exactly same as original site. Without knowing the truth user tries to log on with their account information, hacker records this authentication information and uses it on real site.

Passive attack
In this attack an hacker deploys a sniffer tool and waits for sensitive information to be captured. This information can be used for other types of attacks. It includes packet sniffer tools, traffic analysis software, filtering clear text passwords from unencrypted traffic and seeking authentication information from unprotected communication. Once an hacker found  information he needed, it will be used without the knowledge of the user.

Active Attack
In this attack an hacker does not wait for any sensitive or authentication information. He actively tries to break or bypass the secured systems. It includes viruses, worms, trojan horses, stealing login information, inserting malicious code and penetrating network backbone. Active attacks are the most dangerous in natures. It results in disclosing sensitive information, modification of data or complete data lost.

BlackNurse attack or the low-rate "Ping of Death" attack, the technique can be used to launch several low-volume DoS attacks by sending specially formed Internet Control Message Protocol (ICMP) packets, or 'pings' that overwhelm the processors on server protected by firewalls from Cisco, Palo Alto Networks, among others. 
URL : http://blacknurse.dk/

Above list is not a complete .This will be updating periodically....Please let me know if i miss anything important