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101. Three basic types of distributed trust models are:
102. The following are the basic types of firewall architectures:
103. Hash Algorithms: Hash algorithms produce a hash of a message and encrypt it. They use a mathematical formula for hashing, and it is extremely difficult to tamper with the message and still produce the same hash. Basically, Hashing enable a recipient to check whether a message is received intact without being tampered by a third party.
104. The two primary security services that are provided by IPSec are:
1. Authentication Header (AH), and
2. Encapsulating Security Payload
AH provides the authentication of the sender, and ESP provides encryption of the payload.
105. Some issues that need to be taken care of, while planning security policies are:
106. Social engineering is a skill that an attacker uses to trick an innocent person such as an employee of a company into doing a favour. For example, the attacker may hold packages with both the hands and request a person with appropriate permission to enter a building to open the door. Social Engineering is considered to be the most successful tool that hackers use.
107. The following are the most commonly used access control mechanisms:
108. DNS server uses UDP for name resolution uses port 53. Web server uses port 80. DHCP uses port 67 by default. FTP uses port 21.
109. Block cipher derives its name from the fact that a block of data is taken at a time to cipher.
110. Usually the user names and passwords are transmitted in plain text. But this kind of transmission of authentication details is not secure. Any body with a packet sniffer can read the login and password. Kerberos is basically an authentication protocol that uses secret-key cryptography for secure authentication. In Kerberos, all authentication takes place between clients and servers. The name Kerberos comes from Greek mythology; it is the three-headed dog that guarded the entrance to Hades. It was developed by the Massachusetts Institute of Technology, USA
111. Biometrics is the ability measure physical characteristics of a
human such as fingerprints, speech etc. These measured values are then used
for authentication purpose. Given below are few of the measurable quantities:
Fingerprint: Scans and matches finger print to a securely stored value.
Voiceprint: Identifies a person by measuring speech pattern.
Iris profile: Identifies a person by using Iris part of the eye.
Signature: Matches an individual’s signature with the stored value.
Password is not a physical character of a human; any one can match a given password once it is known.
112. A token can be a physical device such as a smart card or an electronic process such as RSA’s SecureID token. Tokens provide one of the most secure authentication environments, because typically a token is unique to a user, and it is difficult to spoof.
113. VPN (Short for Virtual Private Network) is private network formed using public Internet. It is formed between two hosts using tunneling protocols such as PPTP, L2TP, etc. Using VPN, you can connect two LANs in geographically distant locations together, as if they were located in the same building. The cost of connecting these LANs together is small since public Internet is used for providing the WAN link.
114. Buffer overflow occurs when the input is more than that allocated
for that purpose. The system doesn’t know what to do with the additional
input, and it may result in freezing of the system, or sometimes to take
control of the system by a hacker. By validating the inputs, it is possible
to reduce this vulnerability to a great extent.
IP address check, and using short input fields are not a solution, and imposes restrictions on access and functionality. Avoiding email input doesn’t help in solving the problem.
115. FTP transfers authentication information in clear text. The security concerns while using FTP also include buffer overflow, and anonymous access. However, the cache mining does not occur while using FTP.
116. Web servers are most prone to CGI script exploits, and buffer overflow
attacks. CGI scripts run at server side performing a given functionality,
such as writing to database or reading from database etc. Hackers may use
the loopholes the scripts to hack in to the web server. Similarly, buffer-overflow
can be used to run undesirable code on the server making it vulnerable.
War-driving is related to exploiting the vulnerabilities in wireless networks. Spam is primarily related to client side machines.
117. Non-repudiation ensures that the sender, as well as the receiver cannot refute having sent or received a message. For example, you receive an email from your perspective employer. By using an unsigned email, it might so happen that your employer later denies having sent any such email. Non-repudiation ensures that neither the sender nor the receiver can deny the transmission or the reception of a message respectively.
118. The VPN can be implemented in any of the following combinations:
a. Gateway-to-gateway VPN
b. Gateway-to-host VPN
c. Host-to-gateway VPN
d. Host-to-host VPN
The host-to-host configuration provides the highest security for the data. However, a Gate-to-Gateway VPN is transparent to the end users.
119. Networking Devices:
120. The Packet Filters work at Network Layer of OSI model.
The Application Layer Proxy works at the Application Layer of OSI model
Network Address Translation (NAT) is primarily used to hide internal network from external network, such as the Internet. A NAT basically translates the internal IP addresses to external IP addresses and vice-versa. This functionality assures that external users do not see the internal IP addresses, and hence the hosts.
A Firewall implemented with stateful technology (like Checkpoint Firewall) works at all layers of the OSI model.
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