Computer Network Security

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slappasswd

In an ad-hoc wireless network all of the devices are wireless. There is no need for an infrastructure connection. If you want to transfer a file from one laptop to another there is no need for a wired connection.

Similarly, if you connect a PDA (Personal Digital Assistant) to another device using wireless there would be no need for a wired connection either.

Ad-hoc connections are temporary, and not designed to stay around for long periods of time. They are connections between mobile devices and do not need to connect to other parts of a network.

For the same speed of a wave (I suppose you are referring to electromagnetic waves), the highest frequency corresponds to the shortest wavelength.

For the same speed of a wave (I suppose you are referring to electromagnetic waves), the highest frequency corresponds to the shortest wavelength.

For the same speed of a wave (I suppose you are referring to electromagnetic waves), the highest frequency corresponds to the shortest wavelength.

For the same speed of a wave (I suppose you are referring to electromagnetic waves), the highest frequency corresponds to the shortest wavelength.

we can use access control list for block iptables...............and how is possible that the sender dont know that all traffic was blocked

Fire WireShark, select the Network Adapter you want to scan and it gets to work. By default, WS will scan all data going out or coming in through that adapter. If you want some specific ones, you can always apply a filter.

Using the same (or different) hardware will work with AES as long as the encryption and decryption use the same key. AES relies on the symmetric encryption key which means the same key is used to lock and unlock the data. The hardware that uses it does not matter.

WEP uses a technique that allows an attacker to quite easily break the key, since part of the key (IV, or Initialization Vector) is in every packet. WPA does not use the same technique and a good WPA key cannot be guessed in a reasonable amount of time.

The Wired Equivalent Privacy (WEP) protocol was designed to add security to WLANs. WEP was intended to give wireless networks the equivalent level of privacy of a comparable wired network. However, WEP occasionally produces cryptologically weak ciphers that are easily broken with modern tools. A step-by-step description of how the WEP protocol is cracked follows, to give you a better idea of the weakness of WEP and the speed with which it can be compromised:

1. A hacker runs Kismet, a wireless LAN discovery tool, to determine what wireless LANs are in the area. When the hacker discovers the SSID, the channel number it is operating on, and its BSSID (Basic Service Set Identifier- its Ethernet address), he has all the information needed to mount an attack to recover the WEP key.

2. If the SSID is unknown because the WLAN's owner has enabled a mode that hides it (known as SSID Cloaking or SSID Broadcast Disable), the hacker can discover the SSID by waiting for a client to connect, in which case both the client as well as the AP disclose the SSID. Or the hacker can obtain the SSID by forcing an already connected client to disconnect and reconnect. This is done by sending a specially crafted packet pretending to be from the AP that tells the receiving client that it is no longer authenticated. The client has no way to tell that this is not actually coming from the AP, and so it attempts to rectify the problem by disconnecting from the AP and reconnecting, yielding the SSID in the process.

3. The hacker puts his wireless card into a "monitor mode" in which the WLAN card eavesdrops on a WLAN without having to connect to it. He commands the WLAN card to monitor the channel on which the target AP is located, and begins capturing and saving all of the traffic monitored from that AP to disk in a file called a capture file.

4. The software used to capture the data notes the reception of packets encrypted with a weak Initialization Vector (IV), which in cryptography is a value used to initialize a cryptographic process. WEP misuses these IVs in an exploitable way, and when a certain number of weak IVs have been captured, the WEP key can be determined. Roughly 125,000 packets are required to crack most 40-bit WEP keys, and 200,000-250,000 packets for a 128-bit WEP key.

5. On a slow WLAN, capturing the requisite number of weak IVs can take some time. To accelerate the attack, the hacker will next inject a captured WEP frame back into the network to generate more traffic. This takes advantage of the fact that WEP has no "replay protection" mechanism to prevent this. An injection rate of 512 packets per second generally results in the required number of IVs being captured between 10 min for 40-bit and 30 min for 128-bit WEP. If no client is present on the WLAN to generate traffic that can be captured and reinjected, in most cases the attacker's own system can be made to do so.

6. After a sufficient number of IVs is captured, the hacker runs the AirCrack tool, which will attempt to crack and disclose the WEP key.

7. Once the WEP key is known, the hacker can connect to the AP just as a legitimate client would - and the WLAN owner would be none the wiser.

1. Attacks from a single source can be easily defeated with an IP block. Thousands of different IPs make this a much more difficult attack to stop.
2. More sources means more computers. More computers means more computing power. This is especially useful for DoS attacks, where the more requests you can send out the better your attack is.
3. It's much harder to find the original source of an attacker when there are many attacks from different physical locations.
   

These days, the use of DES is not recommended due to the short length of the key. In the past, the advantage was that the encryption made your information confidential unless you had the unlock key.

In today's environment, DES is easily crackable. Going towards the use of AES, or 3DES, would be more desirable.

A protocol is a set of rules for describing how to successfully exchange information between two systems.

NIC's can perform in the Data Link Layer of the OSI model. However, they can also perform services in the Physical Layer.

(Network+ Guide to Networking Answer)
Physical and Data Link layers

It might be one of fans is failing.

CCNA is a certificate offered by Cisco, which indicates the individual has an entry-level understanding of networking with Cisco equipment. Therefore, CCNA courses prepare you to take and pass the CCNA exam.

DES is a widely-used method of data encryption using a private key that was judged so difficult to break by the U.S. government that it was restricted for exportation to other countries. There are 72,000,000,000,000,000 (72 quadrillion) possible encryption keys that can be used.

For each given message, the key is chosen at random from among this enormous number of keys.

DiD elements focus on what three areas People, operations and defense of the environment This is the answer.....

The Department of Public Safety trains and supervises the Institutional Security Officer staff assigned to foot patrol of the campus, as well as those Institutional Security Officers assigned to the security of the residential buildings.

The security policy anything really, whatever your admin enforces. Everything from what programs you are allowed to what wallpaper you have can be controlled through GPO's. Usually you will find the common one are that every computer has to get updates, every computer has to have an AV etc...

Rivest, Shamir and Adleman, the inventors of the algorithm. Rivest Shamir Adleman (RSA) Authentication Mechanism is used to simplify the security environment for the Flexible Management Topology. It supports the ability to securely and easily register new servers to the Flexible Management topology. With the Flexible Management topology, you can submit and manage administrative jobs, locally or remotely, by using a job manager that manages applications, performs product maintenance, modifies configurations, and controls the application server runtime. The RSA authentication mechanism is only used for server-to-server administrative authentication, such as admin connector and file transfer requests. The

I have a problem with a 2000 LW1 saturn. It's an intermittent problem. Ocassionally will not start until today. Today the car had to be towed, it would crank over but not start. The crank position sensor and control module have been changed. The problem is still there. The fuel pressure is at 55 (between 50 and 60) so that rules out fuel pump and fuel filter. Not sure if it is getting spark. I used a spark tester and it didn't look like it was getting a spark. I was told it may be a temp sensor? Not sure what to look at next! Please help!!

Don W

Michigan

1. Receipt 2. written or oral response 3. Independent Third party 4. Requested by the Auditor

Cromzie: You're not able to access that computer over the network because you're not authenticated to that certain computer. Access denied meaning you are not authorized, you are not an administrator for that computer. Go control panel\user accounts. then add your user account there.

Any compliance body looks for how complete security cover is established in an organization. Most controls points can be established in limiting access to resources. When workflows are clearly made, it is mandatory to chalk out the exact authority over business systems.