Computer Network Security

A. True

staff passwords are not changed regularly

Security exercises should be conducted for several reasons:

1) to keep those with responsibilities for executing incident response familiar with policies, procedures, tools, and their own responsibilities

2) to identify potential flaws in security so that they can be remediated or mitigated

3) to train people new to security responsibilities

4) to keep those with security responsibilities in a mindset to always be thinking about security - rather than getting focused on other day-to-day operational responsibilities and neglecting security

5) to provide incentive to those with security responsibilities to keep security well-maintained lest they be embarrassed during a security exercise

This is known as a "foreign key" (the data it points to is foreign to the current record). It is also commonly called a "foreign key constraint", usually in database systems where the database will perform additional data integrity checks when a primary key is updated or removed (such as restricting deletion of the primary record, clearing the value in the foreign key field, or cascading the deletion to the related records).

Unauthorised modification is changing the contents of a file without the granted permission

Defense in depth is a concept where there are multiple layers of protection. An analogy would be the way a castle is defended. The first layer of defense could be clearing the area around the castle to prevent attackers from having anything to hide behind. The next layer might be a moat around the castle that would make getting to the castle wall difficult. The next layer might be a thick outer wall that is difficult to breach. Making the wall high would be another layer of protection, making it hard to go OVER the wall. Archers mounted on top of the wall would be another layer of protection. Providing arrow slits for the archers to shoot through would provide more protection for the archers and make them more effective at defending the castle. The castle might aslo contain an inner-keep that provides another layer of defense that would have to be breached in order to get to those inside.

In computers the defense-in-depth could be achieved by combining many different protections to build up to greater overall protection. If one defense is breached there are still other protections in place that can thwart the attack. Anti-virus software, firewalls, e-mail filters, security training, policies and proceedures, physical access limitations, system backups, system redundancy, contingency planning, and many other technical, policy, and procedure protections can be combined to provide good overall security for a computer system.

Marcus Ranum, the CSO of the company Tenable, is known for building the worlds first firewall. He was named an industry pioneer by SC Magazine in 2009.

i want to broker anther network key

firewall

There are three (3) ways to do switching: circuit switching, message switching, and packet switching.

A network may employ 2 of these (message switching and packet switching) to send and receive data.

The number of ports vary with the router - some as few as 4, and some many more than that.

Straight through cables can be used to connect devices together via switches, hubs, routers, bridges.

A core switch is one that ties all the communication together. A switch allows computers to connect together. A core switch ties switches together.

If it is the same computer, then the users are presumably physically accessing the computer. The low-tech approach would be to use a post-it note.

Electronically, there are many ways to accomplish this. You might have a logon script that checks a certain file for information and then displays it on the screen for a user, you might schedule a task to be run at a certain time, etc.

A symmetric cipher is an algorithm that uses the same secret (private key) for both encryption and decryption. An asymmetric cipher is an algorithm that uses two different secrets, a public key for encryption, and a private key for decryption.

In English, basically the job of cryptography algorithms are to make text or files jumbled so it can't be read except by the desired recipients. Different algorithms use different techniques for doing this such as switching the order of letters or substituting them with a different letter, and the secret provides the exact instructions on how to do that.

Yes, I'm sure someone has implemented the functionality. The newer versions of REXX may have a function call to create the hash value.

No you can't, you just do not have enough resources for that. It does not matter how much infected computers you have, the number of computers in internet is more. And because for DDoS requirements (many computers sending requests to one particular adddress) you have to have all internet infected, nobody can do that.

You need to be very reliable you don't need to open someone else data and says don't bother you need to be very responsible you need to be able to do your own things with abusing anything without altering without erasing and the security measures should never be neglected you need to be consistent

a tcp header contains the information of the source and destination networks and well as what port to access with out it the packet would not know where to go

Pslist lists detailed process information. It shows which process is running, the CPU time and Elapsed time of the process, along with other details

A signal jammer or jamming transmitter is a small, low-powered transmitter that interfers with receivers in an area around the jammer. The radius of the area will depend on the power of the jammer. The jammer signal will be "seen" by the receiver and it won't then be able to "see" the little signal of the remotely located transmitter that it is trying to "look at" before you turn on your jammer. The jammer transmits a signal (without modulation - it's just the carrier wave) that radiates from the jammer pretty much in all directions (for an omni-directional antenna - which is what is usually on them). This small signal reaches all receivers within the area of its effective range and "swamps" the receivers in that area. Understand that the transmitters reaching out to receivers are generally "high power" units (their power varying depending on what they're designed to do). The jammer is low power. But because the signal from the transmitter is (almost always) a long, long way away from the receivers in the jammer's area, the signal from the transmitter is very tiny in that area. The jammer, on the other hand, has a "large" signal in that area because it's so close to those receivers. It's the amount of signal that gets to a receiver that is important. If a tiny transmitter (a jammer) is "right on top" of a receiver, it will "hit" that receiver hard compared to the tiny signal getting to that receiver from the (high powered) transmitter many miles away. The general rule for power for a transmitter getting to a receiver is that the signal strength is going to be the inverse sqare of the distance from that transmitter. That means that if you have "x" amount of signal at a given spot from a transmitter and them double your distance from the transmitter, the signal will be 1/d2 or 1/22 or 1/4th the amount you had before. Double the distance again and you're down to 1/16th the original amount of signal. A little transmitter works well to jam a receiver if it's right on top of it. It will "blind" the receiver to the "real" signal from the transmitter it is trying to capture. Jammers are generally a no-no, both ethically and legally. Use your head here and think through your options if you are planning some "experimental" electronics. It is the FCC (the Feds) that get down on individuals who interfere with communications. They play hard ball. Imagine interrupting air-to-ground communications and interfering with air traffic. They'd lock you up and throw away the key. Seriously.

TTL stands for "Time To Live". This is a piece of data in a network packet that specifies how many routers the packet can pass through before the packet expires and is thrown away.

Every router that the packet travels through subtracts one from the TTL counter. When it reaches zero, the packet expires. The router will drop the packet, and then send a message back to the computer that sent the packet telling it that the packet has expired.

The purpose of the TTL counter is to make routing loops less dangerous. Let me explain....

Routers are devices that look at an incoming data packet and decide where to send it to get it one step closer to its destination. It's possible for one or more routers to be configured such that router A sends the packet to router B, which sends it to router C, which sends it to router A, which then starts it over again. Without the TTL counter, this packet (and any subsequent packet sent to the same destination) would circulate endlessly, taking up bandwidth until someone fixes the routing loop.

However, with TTL, each router subtracts one from the TTL counter until eventually the counter hits zero and the packet goes away, giving someone time to fix the problem before the links are so congested with looping packets that it's no longer possible to talk to the router.

TTL can affect network security in a couple of ways.

Most operating systems set the TTL counter to 64 or 128, which is a pretty large number that will guarantee your packet can get across the Internet.

To improve your network security, you can set your TTL counter to a low number. If your internal network is only four routers wide, you can set your TTL to 4. This will ensure that any packets generated on your network will not travel very far beyond your internal network.

An attacker can also use the TTL feature to probe your network for the existence and address of your routers. This feature is used by the "traceroute" or "tracert" utility. It works by sending out a packet with a TTL of 1. The first router that the packet encounters will decrement the TTL to 0, drop the packet, then send a message to the traceroute program telling it that the packet expired. By looking at the source address of this packet, traceroute knows the address of the first router. Next traceroute sends a packet with a TTL of 2, which causes the packet to expire at the second router, which sends a message back to traceroute and exposing its address. And so on.

Once an attacker knows the addresses of your routers, he or she can start working on compromising them, which can cause you no end of security problems.

The solution is to prevent these packets from reaching your routers by using a firewall to block them.

HTH,

Gdunge

Yes.