Contractors use the word firewall to denote a physical barrier to keep flames from spreading from room to room. Home networks also have (or should have) firewalls. These are hardware, software or a combination of the two which protects a network from being accessed by unauthorized persons and by malicious software.

Computer firewalls can protect your system in two ways. They can keep programs from making connections to the internet, which keeps an infected program or a virus from spreading. More commonly, however, the purpose of home networking firewalls is to keep your system shielded from outside attempts to access it. Unauthorized access attempts may be from the internet, other computers on your own home network, or even “wardrivers” (hackers passing through with wireless computers) who can simply drive by and put a virus on your network.

Protecting your network from some types of access can make it more difficult for them, even if they manage to get to your network.Of course, blocking all traffic going both ways would make having a network useless. Network security is all about striking a balance between keeping some traffic out while allowing access for the traffic you want. Where exactly this balance lies is a difficult question. There are a number of more or less standard items which people should pay attention to when trying to implement effective firewalls system. The two most common are the UDP and TCP protocols.

UDP is a broadcast protocol and does not require you to have a two way connection. TCP, by contrast is two directional. UDP can be incoming or outgoing, for instance when you ping a server. When you want to open a port in your firewalls, you typically have to specify both port number and protocol. What you should aim for is close any port that you don’t know for sure that you need open. Only open ports or allow protocols in the direction you need – and only when you know that you do. Closed in both directions should be the standard unless needed.

HTTP: This is the standard protocol used for data requests over the internet, both sending (uploading) or receiving (accessing web pages, downloading). Your system firewalls should have port 80 open for HTTP. Secure HHTP (or HTTPS) uses port 443 instead. Port 8080 is also common for HTTP connections.

FTP:  Commonly used for file transfer over networks, you’ll need to open port 20 for this protocol.

SMTP:  Used for sending and receiving email, this protocol requires port 25 to be opened.

POP3: Also used for many email systems. Open port 110 for incoming POP3 traffic.

DNS: DNS needs to both send and receive in order to perform the function of translating IP addresses into domain names. Open port 53 in both directions for this important functionality.

DHCP:  If your IP address is dynamically assigned rather than static you’ll need to open port 68 to allow this protocol.

DOOM:  If you play Doom, you’re going to need to open port 666. Otherwise, as with any other port you won’t be using, close it in both directions.

A lot other ports are used by various services, such as port 1433 (Microsoft SQL Server needs this one). Any program which needs a particular port should mention this in the documentation. Be careful when setting up your network firewalls system because it will provide good security to you!




By: Joseph Nyamache

As more people are logging onto the Internet everyday, Network Security becomes a larger issue. In the United States, identity theft and computer fraud are among the fastest rising crimes. It is important to protect your network and ensure the safety of all computers and users in that network.

What is a Network?

In order to fully understand network security, one must first understand what exactly a network is. A network is a group of computers that are connected. Computers can be connected in a variety of ways. Some of these ways include a USB port, phone line connection, Ethernet connection, or a wireless connection. The Internet is basically a network of networks. An Internet Service Provider (ISP) is also a network. When a computer connects to the internet, it joins the ISP’s network which is joined with a variety of other networks, which are joined with even more networks, and so on. These networks all encompass the Internet. The vast amount of computers on the Internet, and the number of ISPs and large networks makes network security a must.

Common Network Security Breeches

Hackers often try to hack into vulnerable networks. Hackers use a variety of different attacks to cripple a network. Whether you have a home network or a LAN, it is important to know how hackers will attack a network.

One common way for a hacker to wreak havoc is to achieve access to things that ordinary users shouldn’t have access to. In any network, administrators have the ability to make certain parts of the network “unauthorized access.” If a hacker is able to gain access to a protected area of the network, he or she can possibly affect all of the computers on the network. Some hackers attempt to break into certain networks and release viruses that affect all of the computers in the network. Some hackers can also view information that they are not supposed to see.

Destructive Attacks

There are two major categories for destructive attacks to a network. Data Diddling is the first attack. It usually is not immediately apparent that something is wrong with your computer when it has been subjected to a data fiddler. Data fiddlers will generally change numbers or files slightly, and the damage becomes apparent much later. Once a problem is discovered, it can be very difficult to trust any of your previous data because the culprit could have potentially fooled with many different documents.

The second type of data destruction is outright deletion. Some hackers will simply hack into a computer and delete essential files. This inevitably causes major problems for any business and can even lead to a computer being deemed useless. Hackers can rip operating systems apart and cause terrible problems to a network or a computer.

The Importance of Network Security

Knowing how destructive hackers can be shows you the importance of Network Security. Most networks have firewalls enabled that block hackers and viruses. Having anti-virus software on all computers in a network is a must. In a network, all of the computers are connected, so that if one computer gets a virus, all of the other computers can be adversely affected by this same virus. Any network administrator should have all of the essential files on back up disks. If a file is deleted by a hacker, but you have it on back up, then there is no issue. When files are lost forever, major problems ensue. Network security is an important thing for a business, or a home. Hackers try to make people’s lives difficult, but if you are ready for them, your network will be safe.

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By: mohan mittal