Uses of free Unix-based Security Tools to Develope Secure Systems – Part 4


“Enumeration can best be defined as the process of counting. From a security standpoint, it’s the process the attacker follows before an attack. The attacker is attempting to count or identify systems and understand their role or purpose.

This may mean the identification of open ports, applications, vulnerable services, DNS or NetBIOS names, and IP addresses before an attack.”

Michael Gregg (2008, p 149)

This means at this stage it’s only a matter of time before the attacker compromises a system on the network.

The main aim of this stage is to find:


Uses of free Unix-based Security Tools to Develope Secure Systems – Part 3


At this stage an attacker would’ve got a list of IP ranges, DNS servers, Mail servers, employee names and phone numbers. All this would be used by attackers to probe our network to see which systems are alive and the services running on them.

There are many tools and techniques available to accomplish this.

Ping sweeps basically a method used to find out which of a range of IP addresses are a live and reachable from the internet.

Fping can be used on large networks, it doesn’t wait for a reply before trying the next IP, it sends many requests in parallel.

root@bt:#fping -a -f ipadd.txt

-a – shows systems that are alive.

-d – resolves hostnames.

-f – read from file.

-h – help.

Nmap is another tool that can be used for ping sweeps.

root@bt:#nmap –sP

There are other methods that can be used if ICMP is blocked but they are not as accurate as Continue reading Uses of free Unix-based Security Tools to Develope Secure Systems – Part 3

Uses of free Unix-based Security Tools to Develope Secure Systems – Part 2


The aim of foot printing is to gather as much information as possible about the organisation and its network. One would ask why would I need to perform such step when I have all the information about my network?

Joel Scambray, Stuart McClure and George Kurtz (2009, page 10), answers this question:

“Foot printing is necessary for one basic reason: it gives you a picture of what the hacker sees. And if you know what the hacker sees, you know what potential security exposures you have in your environment. And when you know what exposures you have, you know how to prevent exploitation.

Hackers are very good at one thing: getting inside your head, and you don’t even know it. They are systematic and methodical in gathering all pieces of information related to the technologies used in your environment. Without a sound methodology for performing this type of reconnaissance yourself, you are likely to miss key pieces of information related to a specific technology or organization—but trust me, the hacker won’t.”


“Foot printing is one of the most important steps and it must be performed accurately and in a controlled fashion.” Continue reading Uses of free Unix-based Security Tools to Develope Secure Systems – Part 2

Uses of free Unix-based Security Tools to Develope Secure Systems – Part 1


In today’s world it is very rare to find a business or an organisation that is not reliant on a computer network of some sort, whether it is a hospital, a school, large bookstore, small shop or even a home business. This sets a challenge for IT professionals around the world, especially with the increased number of network attacks that are happening every day. The challenge is how to keep these networks secure?

What is network security?

Network security to IT professionals doesn’t mean that a network is 100% secure because that is impossible unless you completely disconnect your network from the outside world and even that doesn’t protect the network from internal attacks or the physical theft of the computer and the data inside it. The only way to have 100% security is to power off all computers and for businesses these days that isn’t an effective decision. Continue reading Uses of free Unix-based Security Tools to Develope Secure Systems – Part 1

3. Media and Connectors Part 2

Coaxial cable – was used on networks in the olden days, however today’s networks moved on to faster and tougher cables. This is not to say that coaxial cables will no longer be encountered as some networks that used this type of cable might still do so because their environment is still the same and so they feel that there’s no need to upgrade.

English: A cutaway diagram of a coaxial cable

Image via Wikipedia

The above figure shows an example of a coaxial cable, which looks similar to the cables used for TVs.

There are two types of this cable Thick and Thin coaxial, although the two are no longer popular; out of the two thin coaxial is more popular. It’s about 0.25 inches in diameter and has a max length of about 185 meters and they use the BNC connector.

Continue reading 3. Media and Connectors Part 2

4. Wiring Standards and Specialised Cable

68A and 568B Standard

The Telecommunications Industry Association (TIA) and the Electronics Industry Association (EIA) have designed a wiring standard called 568A and 568B, which is used for the RJ-45 connectors on a UTP/STP cable. The number 568 refers to the order the wires within the Cat 5, Cat 3 and Cat 6 cables are terminated and attached to the connector. Both standards (568A and 568B) are the same in terms of the signal with a slight difference in the order the pins are terminated. They’re both used for patch cords in Ethernet networks. To be able to make these cables (in case you have to) you need to know which order to connect the wires to the connector. The following figure illustrates this, the pin numbers are read left to right while the connector tab facing down.

     Image taken from Mike Harwood’s Network+ Guide
Continue reading 4. Wiring Standards and Specialised Cable


By clicking on the networking menu above you’ll find a page that aims at providing tutorials on various networking topics. At the moment I’m trying to provide tutorials that help those preparing for any of the certifications such as CompTIA Network + to reinforce the materials they’ve studied. The topics I’m planning to discuss are as follows:

  1. Network +
  2. Security +
  3. CCNA Networking
  4. CCNA Security

After finishing with these I’ll then focus on the main topic of the site, which is Information Security and can be tracked from this home page (front main page of the site). Some of the topics I’m planning on discussing here are:

  1. Information Security principles (cryptography)
  2. Network Security
  3. Systems Security
  4. Applications Security
  5. Intrusion Detection
  6. PenTesting

So please be patient with me as amongst other things (looking for employment, family life, etc) it took me a while to get familiar with the interface to set this site up because it is my first site or blog.



2. Media and Connectors

Administrators must have solid knowledge of the logical standards and the physical media used on today’s networks.

Logical standards define the characteristics such as the configuration of the network, the speed at which they operate and how devices access the network.

Physical media refers to the cabling and connectors used to create the network.

The above two define and dictate the maximum distance between devices, the capability of media to withstand outside interference and even how much space is required in wiring closets and equipment cabinets. Choosing the correct media is very important because they form the foundation for the entire network.

When working with any media, you must be aware of the factors that influence its suitability for a given network implementation.

Interference, transmission speed, media length and installation and repair are some of the most common factors that affect media.

Media Interference (EMI) – common sources of EMI (electromagnetic Interference) are:

  • Computer Monitors.
  • Fluorescent light fixtures.
  • Basically anything that creates an electromagnetic field.

Continue reading 2. Media and Connectors

1. Introduction to Computer Networks

A network can be any connected devices. It can be as small as two computers or as complex as a multisite network such as a telecommunications infrastructure that contains 100s if not 1000s of computers that are connected together.

The common uses of a network are:

  • Communication video conferencing, email, chats, learning, etc…
  • Sharing Hardware – printers, scanners, storage…
  • Sharing data – files.
  • Sharing applications – Microsoft word, spread sheet, specialised software, etc.
  • Data Backup and retrieval

1.1     Types of Networks

1.1.1     LANs and WANs

They types of network used are dictated by the number of locations they span.

LANs – Local Area Networks are restricted to a single location (building, office, school).

WANs – Wide Area Networks spread over multiple geographic locations. They are slower than LANs and more expensive and they tend to use different technologies to connect LANs together to create an internetwork.

Continue reading 1. Introduction to Computer Networks


Information systems have become very important in every business not only that, today you can hardly find a business, organisation or even home businesses that doesn’t have a computer network of some sort. These businesses have become very dependent on these systems for their daily day-to-day operations. Thus the effectiveness of organisation’s business performance has become greatly dependant on the availability, reliability and security of these computers and the networks they’re connected to.

Continue reading Introduction