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1. Download Angry IP Scanner from www.angryip.org/w/Download.

2. Enter the IP address of the target system in the Host or IP Address field or enter a range or IP address for your lab systems and click Start to perform a conventional (full connect) scan of standard ports.

   
   

The DNS infrastructure of the Internet plays a critical role in resolving host and domain names into IP addresses. A great deal of effort has gone into ensuring that DNS works efficiently and is resilient in the face of server failures, incorrect data, or malicious attempts to disrupt the system. But even with these safeguards in place, the system is still subject to attack.

The potential benefit for someone involved in Internet fraud is huge. If you can change the DNS records for a major bank so that they point to your fake site, then you can potentially capture the account numbers and passwords of anyone who logs into the system. This approach sidesteps the need to send out email messages that try to get users to log in, but it does require a high level of technical sophistication. Two approaches have been used: DNS Poisoning and Pharming .

DNS servers around the Internet keep their tables updated by querying other more authoritative servers. The structure is a hierarchy with the network root servers at its origin. In a DNS poisoning attack, DNS servers are manipulated to fetch updated, incorrect DNS records from a server that has been set up by the attacker. This is a sophisticated type of attack to which modern DNS servers are largely immune. But successful attacks do still take place, usually by exploiting bugs in the server software. In March 2005, the SANS Internet Storm Center reported one such attack in which users were redirected to sites that contained spyware, which was then downloaded to users' computers. A detailed report on this attack can be found at http://isc.sans.org/presentations/dnspoisoning.php.

Pharming is somewhat of an umbrella term for several different approaches to manipulating DNS records. Rather than going after DNS servers directly, an attacker may try to con a domain registrar into changing the authoritative DNS record for a domain to point to their fake site. Examples of this form of social engineering have included someone simply calling a registrar on the phone and persuading them that they represent the owner of the target domain.

One example of this involved the New York-based Internet service provider Panix. In January 2005, an attacker was able to transfer control of its DNS records to a server in the United Kingdom, with all company email being redirected to a server in Canada. Even though the problem was spotted quickly, the impact on the company and its customers was substantial.

Another form of attack takes advantage of the fact that most operating systems have a local file of hostname-to-IP-address mappings that will be queried before making a remote DNS query. If such a file contains a match, then that address will be used without any further lookups. This has been exploited by a computer virus called the Banker Trojan. In addition to logging user keystrokes, it adds lines to the end of a host file on a Windows system that will redirect users to fake bank sites. Many variants of this trojan have been found.

DNS is fundamental to the operation of the Internet and usually works so well that people take it for granted. Attacks like these are a reminder that all components of the Internet are vulnerable.

Skype and Vonage have made most of us aware of Voice over Internet Protocol (VoIP) phone services. Now VoIP solutions aimed at businesses have evolved into "unified communications" services that treat all communications--phone calls, faxes, voice mail, e-mail, Web conferences and more--as discrete units that can all be delivered via any means and to any handset, including cellphones. Two main sets of competitors are fighting it out-- one set is focused on VoIP for medium to large enterprises, while another is targeting the small-to-medium business (SMB) market.

In the latter group, Microsoft (nasdaq: MSFT - news - people ) introduced its Unified Communications line of Office Communicator servers and software in October 2007, and among other competitors is fighting with Cisco (nasdaq: CSCO - news - people ) over whether VoIP will be based on a set of software applications or based on a specific network. Meanwhile, good-enough services for SMBs have become quite good, with RingCentral's Digital Line service leading this pack. We wonder--is tiny start-up RingCentral better positioned for growth in the enterprise than Microsoft, which historically has owned the enterprise?

Winner: RingCentral Digital Line Microsoft's Unified Communications offers the ability to integrate a lot of features into existing Office software, including Web conferencing. Microsoft's positioning seems a little murky--they offer VoIP servers and software that will be interoperable with a company's existing PBX system to customers who don't want to replace robust hardware-based PBX services but want to extend those systems' capabilities. Microsoft also offers VoIP-only solutions that require the installation of Communicator servers.

Part of the murk around Microsoft's positioning is caused by the number of features offered--in addition to the basic call-handling and routing functions, Communicator also offers instant messaging with visual enhancements, e-mail, and audio- or videoconferencing. This desire to be all things to all enterprises can be partially attributed to the fact that Microsoft is fiercely competing to own this space. It's most fierce competition is with Cisco, described in a 2007 article: "[Cisco and Microsoft] agree on a future vision of networked software that will help users access information with the device of their choosing and share it in ever more useful ways. Cisco thinks the key is to build most of these smarts into the network. Microsoft executives believe the priority is still the programs people use to actually get things done."

In contrast, what makes RingCentral so potentially disruptive is that it offers an inexpensive ($99 per month per user), Web-only solution with no hardware to be installed at all, except for handsets which the customer supplies. Reportedly, with the right handset and a good enough Internet connection, RingCentral offers excellent quality. RingCentral enables small and midsize businesses to have what might otherwise be unaffordable smart-PBX features, including call control, extensions, Outlook integration for dialing and faxing, hold music, call logs, and rules-based call routing and answering.

RingCentral has actually seen its business grow in the recession--a Nov. 3 article reported record sales in October for the company. A company survey indicated many of the sales were from SMBs cutting costs due to the economic downturn--either getting rid of physical office space and thus needing a unified phone system not dependent on physical space, or SMBs discontinuing landline service and using RingCentral to send some calls to cellphones.

If RingCentral is able to get enough of a toehold into the SMB market for VoIP, it's possible the company could end up growing into the midsize enterprise market as businesses that use it grow and decide not to change. At that point, it would potentially be a threat to Microsoft, which runs a risk of overshooting the market, by producing features that add complexity and cost without really mattering to many companies.

Microsoft said Tuesday it has opened a new research center in Switzerland to develop internet telephony software, also known as Voice-over-IP.

The U.S. tech giant said the center, located in Zurich, will grow from 45 to 200 staff over the next three years.

Microsoft Corp. (nasdaq: MSFT - news - people ) said in a press release that the site complements three other centers developing communications software in Beijing, China; Hyderabad, India; and Redmond, Washington.