Network / Port Address Translation

Network Address Translation (NAT) is the process of modifying IP address information in IP packet headers while in transit across a traffic routing device.

The simplest type of NAT provides a one to one translation of IP addresses. RFC 2663 refers to this type of NAT as basic NAT. It is often also referred to as one-to-one NAT. In this type of NAT only the IP addresses, IP header checksum and any higher level checksums that include the IP address need to be changed. The rest of the packet can be left untouched. Basic NATs can be used when there is a requirement to interconnect two IP networks with incompatible addressing.

However it is common to hide an entire IP address space, usually consisting of private IP addresses, behind a single IP address in another address space. To avoid ambiguity in the handling of returned packets, a one-to-many NAT must alter higher level information such as TCP/UDP ports in outgoing communications and must maintain a translation table so that return packets can be correctly translated back. RFC 2663 uses the term “Network Address and Port Translation” NAPT for this type of NAT. Other names include Port Address Translation PAT, IP masquerading, NAT Overload and many-to-one NAT. Since this is the most common type of NAT it is often referred to simply as NAT.

Perimeter Router, Internal Router and Firewall

The perimeter router is typically a standard router providing a serial connection to the outside world and a LAN connection to the internal network. The perimeter router should provide any filtering of outside traffic to implement basic security for the DMZ and preliminary filtering for the inside network. This device could be running the firewall feature set for additional security options.

A firewall can either be software-based or hardware-based and is used to help keep a network secure. Its primary objective is to control the incoming and outgoing traffic of network by analysing the data packets and determining whether it should be allowed through or not, based on a predetermined rule set. A network's firewall builds a brigade between an internal network that is assumed to be secure and trusted, and another network, usually an external (inter)network, such as the Internet, that is not assumed to be secure and trusted.

The internal router takes care of the internal network of the company such as NAT.

Such as network that has all 3 are more common in medium and large business where they would need greater protection and performance and well as greater routing options. The firewall is separated from the router and there is 1 router to take care of the external and internal network. The workload is split between different machines and therefore, they would be able to perform better and they have more computing resource to perform that function.

Security Policy

A security policy is a document that states in writing how a company plans to protect the company's physical and information technology assets. A security policy document is never finished, but is continuously updated as technology and employee requirements change. A company's security policy may include an acceptable use policy, a description of how the company plans to educate its employees about protecting the company's assets, an explanation of how security measurements will be carried out and enforced, and a procedure for evaluating the effectiveness of the security policy to ensure that necessary corrections will be made.

If it is important to be secure, then it is important to be sure all of the security policy is enforced by mechanisms that are strong enough. There are organized methodologies and risk assessment strategies to assure completeness of security policies and assure that they are completely enforced. In complex systems, such as information systems, policies can be decomposed into sub-policies to facilitate the allocation of security mechanisms to enforce sub-policies. However, this practice has pitfalls. It is too easy to simply go directly to the sub-policies, which are essentially the rules of operation and dispense with the top level policy. That gives the false sense that the rules of operation address some overall definition of security when they do not. Because it is so difficult to think clearly with completeness about security, rules of operation stated as "sub-policies" with no "super-policy" usually turn out to be rambling rules that fail to enforce anything with completeness. Consequently, a top level security policy is essential to any serious security scheme and sub-policies and rules of operation are meaningless without it.

Common Networking Attacks Threats and Solution

USB drives are one of the common ways you can infect a network from inside a firewall. The ubiquity of thumb drives has driven hackers to develop targeted malware that can automatically execute upon connecting with a live USB port.  What's worse is that default operating system configurations typically allow most programs to run automatically. They are also inexpensive, small, hold a lot of data and can be used between multiple computer types.

A solution to this problem is to change the computer's default autorun policies. (Click HERE! To findout how!)

All companies have some forms of sensitive information that absolutely cannot leave the walls of the building. It becomes very dangerous when that information is stored on an unsecured portable computer, as they are easy to walk off with. There have been many cases of publicly disclosed instances of notebooks with sensitive data that have "gone missing." Unless the laptop employs a tough encryption algorithm, data is often easy to recover from any given file system. Implement an encrypted file system for sensitive data.

There are a number of off-the-shelf solutions out there to choose from, along with open source ones such as TrueCrypt. VPN, DV and Wi-Fi access should not be stored persistently on devices such as laptops or netbooks.

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