This paper will discuss some of the different types of Internet attacks companies have to guard against including Trojan horses, denial of service attacks, and viruses. This paper will also look at some of the different types of security tools and standards that can be used to defend against these attacks such as firewalls, cryptography, digital certificates.

Trojan horses are an increasingly popular instrument for intruders to use. A Trojan horse is an apparently useful program containing hidden functions that can exploit the privileges of the user running t

A Web server certificate is a certificate that authenticates the identity of a Web site to visiting browsers. When a browser wants to send confidential information to a Web server, the browser will access the server's digital certificate. The certificate, which contains the Web server's public key, will be used to authenticate the identity of the Web site and encrypt the information for the server using Secure Sockets Layer technology.

Here is how these certificates are used in Internet transactions: I visit a Web site secured with SSL. My browser sends a 'client hello' message to the Web server indicating that a secure session is requested. The Web server responds by sending me it's server certificate which includes it's public key. My browser will verify that the server's certificate is valid and has been signed by a CA whose certificate is in the browser's database. It will also verify that the CA certificate has not expired. If the certificates are all valid, my browser will generate a one-time unique session key and encrypt it with the server's public key. My browser will then send the encrypted session key to the server so that we will both have a copy. The server will decrypt the message using its private key and recover the session key. From then on, I can be assured that the web site I am communicating with is the one it claims to be and that only the Web site and my browser have the only copies of the session key and secure communications can commence.

Not only do these attacks prevent Web sites from serving their customers, depending on the size of the attack they can also slow down the entire Internet. According to Keynote Systems, a firm that measures Internet and Web site performance, during the period of recent Internet DoS attacks the performance of the top 40 Web sites was degraded by 60%.

Denial of service (DoS) attacks are aimed at devices and networks with exposure to the Internet. Their goal is to cripple a device or network so that external users no longer have access to your network resources. Without hacking password files or stealing sensitive data, a denial of service hacker simply fires up a program that will generate enough traffic to your site that it denies service to the site's legitimate users.

Using a firewall and virus products can protect businesses from some of the popular Trojan horses, although it is impossible to detect all possible Trojan horses. If you do fall victim to a Trojan horse, some anti-virus software may be able to recognize, remove, and repair the damage from the Trojan horse. However, if an intruder gains access to your system via a Trojan horse, it may be difficult or impossible to establish trust in your system. In these cases you may have to rebuild your system from known good software, changing all passwords, and checking other nearby systems.

A basic firewall features two key components: gates and chokes. Gates allow data to pass between two networks. Chokes block incoming packets not destined for the gate and block outgoing packets not coming from the gate. Chokes can be set to block specific types of packets that may be the work of a hacker attempting to invade a system, such as telnet packets. The gates are typically a gateway computer and the choke is often an intelligent router located between the gate and the external network. Three common gateways used are application gateways, circular gateways, and proxy servers. Despite the solid protection they offer, gateways can be difficult for network managers to configure and since they need to pipe all inbound and outbound network traffic through a single point, they increase the risk of creating a substantial bottleneck. That is why vendors offering gateway security products often blend the technique with packet filtering. This approach provides a faster, though potentially less effective solution.

Some common words found in the essay are:
Cryptography Cryptography, Tools Firewalls, Horses Trojan, Sockets Layer, Turbo Tax, Networks Internet, PCs Businesses, Internet Explorer, Scripts Java, Service Denial, trojan horse, trojan horses, public key, web site, denial service, digital certificates, web sites, brute force, web server, credit card, reach organized criminals, identity web site, process converting information, key kept secret, organized criminals major,
Approximate Word count = 3089
Approximate Pages = 12 (250 words per page double spaced)