How do Skype resolvers work?

Question

I'm wondering how Skype resolvers work. Can someone explain?

A Skype resolver is a tool that allows you to determine a user's IP from a Skype username.

Answer 1

Skype calls are peer to peer. As much as possible is done without the need for a centralized server through different types of nodes(clients). There are three types of nodes in the skype network.

• Supernodes
• Regular nodes
• Login server

Any client within the network can become a supernode. Supernodes have a cache of IP-addresses to all other supernodes. If you are behind NAT supernodes will help you UDP hole punch. UDP hole punching is using a third party to connect to another client circumventing the issue of connection directly to someone behind NAT.

Thus, you are connecting directly to the client when issuing a friend request or getting the cached IP of the username.

This has caused much grief within the e-sports community as people are getting the IP of professional gamers and messing with their connection through various means such as DoS attacks.

The next beta is trying to address this issue.