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It is often said that understanding the problem is 90% of the solution, and VoIP security is no exception. It is fear of the unknown which is likely to elicit a knee-jerk reaction of panic, so the first step is to understand the threats and then classify them. We also have to ask the question: what does security mean to me and what does it mean to my customers?

Security to the customer means protecting their device and identity and the continuity of their service. Security to the service provider means protecting their network their revenue and their customers. In this feature we will look at service disruption and service theft.

Disruption

A service can be disrupted by breaking the user's device, flooding the IP network with traffic or breaking the service provider's infrastructure. Disruption is usually achieved through either Logic Attacks or Flood Attacks or Application Layer Attacks.

o Logic attacks exploit vulnerabilities in protocols or their implementations, e.g. Ping of death, Teardrop, Land etc.

o Flood attacks disable targets through traffic volume; a flood attack can originate from a single platform or from multiple platforms.

o Application Layer Attacks include: SIP-SPAM, and identity forging.

We can also divide the attacks into IP layer and SIP layer thus:

IP Logic Attack / IP Flood Attack

SIP Logic Attack / SIP Flood Attack

Application Layer attack

IP Logic Attacks

IP Logic attacks on SIP devices are no different to any other IP device; these include well known exploits such as: Ping of death, Teardrop, Land, Chargen and Out of sequence packets. All of these can disable a device which has not been fully tested to protect itself against these exploits.

IP Flood Attacks

IP Flood attacks include: SYN flood attack (TCP SYN Floods are one of the oldest DoS attacks in existence), Smurf Attack, Fraggle attack and the list goes on... These attacks are designed either to overcome the device by tying up resources or to simply overwhelm the network through shear weight of traffic.

SIP Logic Attacks

SIP logic attacks exploit weaknesses in SIP signalling implementations. Incomplete or incorrect fields, invalid message types can disable not only client devices but also core network devices. This type of attack can be countered by thorough testing of any devices against suites such at the IETF SIP Torture test developed through the SIPiT Events or the PROTOS Test-Suite, developed by the University of Oulu.

A more sophisticated attack can be to inject messages into a call to terminate it prematurely. This type of attack can be largely avoided by the use of strong authentication techniques, thus, the injected packet would not be authenticated and therefore would be rejected.

SIP Flood Attacks

SIP flood attacks exploit weaknesses higher up the communications stack that require more processing resources. As a consequence, it takes a much smaller flood to cause disruption. For example, one or more devices may send multiple registrations or call requests to a server.

Countering this type of disruption requires network based devices like Session Border Controllers (SBCs) to police the signalling stream and rate limit registrations and calls to Softswitches to predetermined limits. Acting as a proxy in the signalling stream the SBC can also filter inappropriate protocols, IP DoS attacks and invalid SIP messages. This helps compartmentalise the network and restricts any disruption to just one network segment.

Protect the User Device

These devices will typically be incapable of rate limiting and may be overrun by flood attacks. This means they are subject to both logic and flood attacks. Again the user device will benefit from the protection afforded by network based SBCs blocking DoS attacks and invalid SIP messages.

Service Theft

A simple example of service theft is to signal that a voice call it being made but exchange video data. This hits the service provider on two fronts: a) loss of revenue by billing for only a voice call and b) potential degradation in service quality for other users resulting in dissatisfaction.

The structure of a VoIP call with separate media and signalling streams has lead to some innovative ploys. For example, a rogue PC client which transports media in the RTCP quality monitoring stream, this is not policed in most networks. Another ploy is to transport media in the call signalling then failing the call before billing commences. Not only does this mean a free call but repeated call set can cause huge signalling rates which are a DoS attack in themselves.

The solution is to police all components of the call. SBCs police the signalling and the media to ensure that the call is executed as requested and that RTCP traffic is within expected bounds.

Conclusion

Security is a vast subject and needs to be ubiquitous in its implementation. Take care of the fundamentals first:

Test, authenticate, protect, block, limit and police.

o Test network elements against standard IP and SIP test suites to ensure they can survive IP and SIP logic attacks

o Implement strong authentication, identifying your users protects their identity, protect their service and combats disruption.

o Protect the Network by compartmentalizing it to restrict the range of any disruption.

o Block malicious or inappropriate traffic - do not propagate the problem.

o Limit the rate of traffic to core elements to ensure the survivability of the service.

o Police all aspects of the traffic flowing across the network to prevent fraudulent or inappropriate use.

A secure and dependable service brings with it benefits to users and provider alike. It will build user confidence which in turn creates dependable revenue for the service provider and by addressing the basics from day one, need not be complex or expensive.

Dave Gladwin is a marketing consultant, formerly Vice President of Product Marketing at Newport Networks Dave has worked in the telecoms sector for over 25 years and product marketing for the over 10 years.

Editing Seeing Red - Secret Communication of Reef Species

Previously unknown to scientists, divers, and even observant aquarium keepers, a secret form of communication between coral reef fishes has been discovered.

Because red light downwelling from the sun is selectively absorbed by seawater, scientists have long assumed that red light is of little importance to reef fishes in shallower waters less than 33 ft. (10 m) deep where blue-green light dominates.

Now a team of researchers has discovered that 32 different reef fishes from 16 genera and five different families have the ability to display red fluorescence in daytime conditions and in waters without natural red light from the sun. Heads, eyes, and fins are the body regions that fluoresce most intensely, and it is surmised that the flashing of color is important in silent underwater communication between aquatic species.

Led by Nico K. Michiels at the University of Tubingen in Germany, the team of researchers also demonstrated red fluorescence in stony corals, macroalgae, polychaete worms, sponges, and feather stars.

Cryptic Signals?

Because many of the fishes and other organisms show cryptic coloration in other parts of the visible spectrum, Michiels says that red fluorescence may be "used as a private communication mechanism in small, benthic, pair or group-living fishes."

"Our findings challenge the notion that red light is of no importance to marine fish, calling for a reassessment of of its role in fish visual ecology in subsurface marine environments," the authors conclude in a paper just released in the Journal ''BMC Ecology.''

Many differences were found between families and genera. Eye rings and parts of the head and thorax most commonly glowed in fishes, with Triplefin Blennies (Trypterygidiidae) able to signal with brightly fluorescing dorsal fins. Some Pseudocheilinus and Paracheilinus wrasses show a "whole-body glow."

Methods Used

The Michiels' team from Tubingen, Austria, and Australia, equipped themselves with dive masks and camera lenses with red filters blocking wavelengths below 600 nanometers. Diving deeper than 15m, where natural red light does not penetrate, they found a world glowing with red. "By emitting a colour that is lacking from the environment, a fish contrasts more against its background," said Michiels.

"Red fluorescence is at the borderline of what is visible to many marine fish, and due to rapid attenuation of red light by water, even those that can see red will be able to see it over short distances only." This seems to support the theory that fluorescence may be most important in communication between members of a species living in close proximity on the reef.

The functionality of sessile invertebrates showing red fluorescence remains to be studied.

Mechanisms Involved

According to the study:

"Dissection revealed that red fluorescence was associated with guanine crystals in pipefish, triplefins, blennies and gobies. Guanine crystals are produced by iridophores and are well known as the source of silvery reflection and iridescence in bony fish. However, they have never been described to show strong red fluorescence....

"Preparations of crystals maintained strong fluorescence after prolonged storage in a dried or liquid form, allowing us to confirm fluorescence in preserved gobies collected up to 5 years before. This is in striking contrast to reflective red pigmentation, which bleaches out within hours after fixation."

Warning to Divers

The study's authors cautioned divers to use great caution in diving with red masks:

"Diving with a red mask is similar to night diving, with dramatically reduced light intensities and viewing distances. Disorientation becomes a serious problem. Moreover, it takes several minutes to adapt to the darkness. Staying in a small, familiar area and moving slowly and carefully is crucial. Furthermore, it is essential to take a torch to read equipment. Dials, indicators and computer backlights are either reflectant or luminesce blue or green, making them effectively illegible at depth in the absence of a local white (red-containing) light source.

"To circumvent this problem, we also used the Oceanic DataMask which has a built-in dive computer that can be read irrespective of any filter attached to the front. Because of these unfamiliar restrictions, we recommend that only experienced divers use this procedure and that only one partner in a buddy team uses a red mask at any given time. We also recommend attaching filters in such a
way that they can be instantly removed without having to change to a spare mask, which one should carry nevertheless."

About the Author

James M. Lawrence is editor of Microcosm Aquarium Explorer, an educational resource for conscientious aquarium keepers, offering thousands of species profiles and identifying images. For color images of fluorescing reef animals and a link to the full report go to Seeing Red Images.

Question about turbocharging my Chevy pickup.?

I have a 400ci small block w/ 750 holley. We all know that turbos need to stay cool and lubed. So on the turbo you have an oil inlet line that goes from the motor to the turbo.

1st question: Where on the motor is this line supposed to come from?
2nd question: Where does my oil return line go?

I think that the inlet line has to come from a pressurized place (like an oil filter adapter or something) and the return line can go to either valve cover.

The turbo kit will have the adaptors you need but you are correct about the pressure source and the return.

Clear iSpot review
Lately, the notion of getting Apple's ever-growing line of mobile devices connected to 3G and 4G networks is attracting a lot of attention from carriers that aren't AT&T -- take Sprint's Overdrive case for the iPad , for instance -- but not in a million years did we think Clear would go so far as to create a mobile hotspot designed exclusively for them. In some ways, that's taking respect for ...

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