Hackszine.com: Skype Archives

Archive: Skype

June 27, 2007

Skype for Nokia N800 coming July 2007

Kevin C. Tofel posts some big news+a great photo (shown above) for N800 fans:

Skype support for the Nokia N800 is right around the corner. I got a chance to see it, but it won't be available as a download until some time in July. The Nokia N800 already supports Gizmo for VoIP, but the addition of Skype adds more choice to make a good mobile device an even better one.

Related Hackery:

Skype Hacks - Link
VoIP Hacks - Link
Nokia Smartphone Hacks - Link

June 1, 2007

UDP Hole Punching: how Skype gets through firewalls

When two machines running Skype need to communicate directly, but are both behind a NAT firewall, there's a clever trick that's employed to start a communication channel. It works like this:

First, both machines open a connection to a non-firewalled server. The server takes note of the source port (which may have been altered by the firewall) and sends this information to the other party to give it an idea of what port future connections might be coming from.

Client A then attempts to connect to a range of ports on client B's machine. All these requests will fail at client B's firewall, of course. However, in the process a side effect has occurred. Client A has told its own firewall to allow traffic from all of client B's scanned ports! Now, when client B attempts to connect to client A, assuming its outgoing port was previously scanned (which it likely will be), the request will get through to client A's machine.

If all else fails, both machines can use a central server to proxy their connection, but the UDP hole punching trick will typically allow two NAT firewalled machines to communicate directly, which means less latency and a significantly lighter load on the server.

Resources:
How Skype & Co. get round firewalls - Link
RFC3489 STUN - Simple Traversal of UDP through NAT - Link

February 9, 2007

Experimental High-resolution Skype for Mac and PC

Jaanus Kase posted instructions over on Skype's developer site for enabling higher quality 640x480 video. You need to upgrade to the latest Skype release (2.5.0.85 or later for mac and 3.0.0.216 for PC), quit Skype, and then edit the config.xml file in your settings directory ("~/Library/Application Support/Skype/[skypeusername]/" in OS X).

You should see an entry that looks similar to:
<Video> <Device>Built-in iSight</Device> </Video>

Modify that to read:
<Video> <CaptureWidth>640</CaptureWidth> <CaptureHeight>480</CaptureHeight> <Device>Built-in iSight</Device> </Video>

When you've finished, your contacts will be seeing you in glorious 640x480 instead of the standard 320x240. There are some tweaks and hardware requirements that might be required for the PC version, so check up on the links below for the nitty-gritty details.

Related links: