How to Avoid Relayed Transfers (Advanced Users Only)

Skype uses relay hosts to transfer files when two Skype applications cannot communicate directly over the Internet. Often, relayed transfers are caused unnecessarily by firewalls, Network Address Translation (NAT) devices, or routers that are not configured to allow UDP packets out and their replies back in.

Most firewalls, NAT devices, and routers are P2P-friendly, which means that they are configured by default to allow for UDP (user datagram protocol) Consistent Translation. If your network hardware uses UDP Consistent Translation, it means that it is P2P-friendly and will permit high-speed (nonrelayed) Skype file transfers.

As a result, opening ports usually is not required, but in some cases, it can help speed file transfers. Depending on the specific network hardware you have, you may be able to avoid relayed file transfers by ensuring that your firewall, NAT device, or router allows UDP packets out and their replies back in.

Refer to the technical documentation (or the vendor Web site) for your firewall or NAT device to determine whether your router uses UDP Consistent Translation or to learn how to configure your firewall and NAT to allow UDP replies in. Refer to Appendix C for more information.

Note

Skype allows system administrators to disable the file-transfer capability. If the Skype application user interface for transferring files is grayed out, it means that someone has configured your Skype application to prevent you from sending or receiving files in this fashion. Refer to Appendix B or consult your system administrator for clarification or help.