ccna 200-301 image

ccna 200-301 image.A reconnaissance attack is usually a prelude to further attacks with the intention of gaining unauthorized access to the network or disrupting network functions. Network security practitioners detect when a reconnaissance attack has occurred by receiving pre-configured alerts. These alerts are triggered when specific parameters, such as ICMP requests per second, are exceeded. There are a variety of techniques and devices that can be used to monitor this type of behavior and generate alerts. CiscoASA provides intrusion prevention on a standalone appliance. In addition, CiscoISR also provides network-based intrusion prevention through the CiscoIOS security image.1.3.2 Access Attacks1.3.2.1 Access AttacksHackers perform access attacks on a network or system for three reasons: to obtain data, to gain access, and to enhance access. Access attacks typically use password attacks to guess system passwords. There are several ways to implement password attacks, including brute-force attacks, Trojans, IP spoofing, and packet sniffers. However, most password attacks use brute-force attacks, which involve repeated attempts to find a user account or password based on a built-in dictionary.A brute-force attack is typically performed using a program running on a network and attempting to log into a shared resource (such as a server). After the attacker gains access to a resource, the attacker has the same privileges as the stolen user account. If the account has high enough privileges, the attacker can create a backdoor for later use without regard to the stolen user account's status or password changes.For example, a user could run the LOphtCrack (or LC5) application to perform a brute-force cracking attack to obtain the password of a Windows server. Once the password is obtained, the attacker can install a keylogger that sends a copy of all keystrokes to the desired destination, or a Trojan horse that sends a copy of all packets sent and received by the target to a specific destination, allowing monitoring of all traffic coming in and out of that server.1.3.2.2 Types of Access AttacksThere are five types of access attacks.Password attacks One-by-one attackers try to guess the system password. A common example is the dictionary attack.Trust Exploitation One attacker uses the privileges granted to the system in an unauthorized manner, which can lead to damage to the target.