|
Knock-Offs Could Cripple Skype |
|
|
|
Written by Adam Gosling
|
|
Monday, 17 July 2006 |
News that a Chinese software company has reverse engineered
the Skype peer-to-peer softphone phone is bad news for users as it threatens to
bring the whole system to a screaming (or jittering) halt.
In what may well be a case of "that was good while it lasted"
free phone calling using Skype may have its days numbered with the impending
release of a Skype knock-off that refuses to play fairly.
There are definite upsides to the potential of a Skype
imitator. It would allow third party developers to include Skype capabilities in
other applications, allow other providers (such as the big instant messenger systems
AOL, Yahoo! and MSN) to develop interoperability between their own products and
the Skype system, even allow for cool interoperability options with Asterisk
switches or other PBX systems, but there's a danger inherent in overloading the
system.
One of the key ingredients of Skype's success has been its
architecture as a distributed system that relies on using Super Nodes to handle
the address book, negotiate call establishment and in some cases relaying calls
when a direct connection between two clients cannot be established.
The Chinese imitation of the Skype client refuse to act as a
Super Node in a Skype network, but it must still rely on other Super Nodes to
achieve its goals.
If the Skype knockoff gains popularity and significantly
increases users this could lead to an overload on existing Super Nodes forcing eBay
to either provide its own servers or risk the system failing.
The news that a successful reverse engineering bid was in underway
is being reported on the blog
of Charlie Paglee, chief executive officer of Vozin Communications.
Paglee, who is said to have spent many years working in China, claims
to know the people doing the reverse engineering on the Skype client and
received a Skype call from the company late last week.
According to his blog the first call failed, the second suffered
from a bad echo at his end and then dropped out after nine minutes. When he
called them back the first call failed but the second call lasted three minutes and had Skype-like quality.
The client being built by the Chinese company, which has not
yet been named, does not yet implement all the Skype features such as presence
and instant messaging, but the company plans to do that over the coming weeks.
They also have some fine tuning to do. The client is not
really stable enough for public release, but the fact that Paglee was able to
receive a call across what is normally a closed system is a huge achievement.
When you consider that the integration between Microsoft's
MSN and Yahoo's Instant Messenger applications has only just reached beta after
nine months of work, the achievement to create interoperability with a closed
system like Skype's is a real achievement.
But is it a good thing?
Skype has been proprietarily secretive about the details of
its technology, but has in the past explained the role of its supernode
technology and it seems pretty critical to making the system work as
effectively as it does.
Paglee says the Chinese company say their client will not
allow itself to play a productive role in the network.
Many users will see this as a definite positive. It may also
reduce the risk of running the client software.
Super Node servers are selected automatically by the system
based on their processing and bandwidth capacity. A Super Node must have an
open, routable IP address and from what Robert X. Cringley
says here, it must be pretty well unprotected.
This third party gets past the Nat Traversal and firewall
problems that would normally make it very difficult to establish a call between
two nodes on separate protected networks.
Each client sets up a connection to a Super Node, registers
login details and listens for incoming calls from that Super Node. This server negotiates
call each call setup and if both clients are restricted to TCP only, the call must
also then be relayed between them by one of these nodes.
So to achieve their goal, the Chinese engineers have had to
decipher the way clients' interact with this server, imitate the communications
protocol used during the calls and fool the receiving Skype client into exchanging
keys and setting up an encrypted tunnel to the imitator.
As both Paglee and Cringley point out, too many clients and
not enough Super Nodes would very quickly bring the Skype network to its knees.
The Cringley piece is well worth the read if you are interested in this.
That could be very bad news for eBay, making Meg Whitman's
next AGM a nightmare, but for the rest of us, we'd just be switching to
GoogleTalk, AIM or MSN/Yahoo!
Skype has so far dismissed the reverse engineering claims
and points out that while the protocol might have been uncovered, there's
little risk of people listening in because the system's encryption processes
remain secure.
Another potentially bad piece of news for eBay is that the
discovery of Skypes inner workings has also lead the Chinese company to develop
an effective way of completely blocking Skype.
"They hold in their hands the key to enabling telcos to
block Skype in China, all of
the Middle East and Africa," says Paglee. It
presumably does this by identifying and blocking Super Nodes.
However, Paglee says the company has no interest in using
their knowledge to block Skype and are more interested in licensing the
technology to other interested parties. In fact, Paglee says they have been
approached by three major Instant Messaging providers already.
Related news items Newer news items
Older news items
|
|
|
|
