Sign In with your
Trend Micro Account
Need Help?
Need More Help?

Create a technical support case if you need further support.

Can InterScan Web Security Suite (IWSS) block Skype connections?

    • Updated:
    • 12 Oct 2015
    • Product/Version:
    • InterScan Web Security Suite 3.1 Windows
    • Platform:
    • Windows 2000 Advanced Server
    • Windows 2000 Server
    • Windows 2003 Enterprise Server
    • Windows 2003 Standard Server Edition
    • Windows 2008 Enterprise Server
    • Windows 2008 Standard Server Edition
Summary

IWSS functions both as an antimalware and content filtering web application and users want to know if it is possible for IWSS to block or prevent Skype from making a call.

Details
Public

IWSS cannot block a Skype connection because Skype does not use pure HTTP/HTTPS to connect. IWSS can only handle or block HTTP/S and FTP traffic so it will not block any of the ports and services that Skype uses for connection.

In order to block Skype, you will need to combine a gateway content filtering and firewall application or device.

To discuss this further, Skype uses supernodes with a range of ports when performing a VOIP call.

    • Skype will attempt to contact supernodes. The IPs of these supernodes are in a file stored with other files that Skype installed.
    • The source ports that Skype attempts to connect from are non-default ports.
    • Once the connection is establish, the rest of the communications are done in TCP over non-default source ports with the range 2940-3000.
    • If the above failed, only then will Skype use the proxy server (IWSS in this case) specified in Internet Explorer and attempt to tunnel the traffic over port 443 using the SSL protocol.
    • The destination IPs are random as above, which makes destination blocking out of the question.
    • An option will be to block SSL connections, but this will affect all other connections going through SSL.
 
This issue has been confirmed in IWSS versions 2.5 and 3.1. IWSS 2.5 has already reached End of Support/End of Life (EOS/EOL).
Premium
Internal
Rating:
Category:
Troubleshoot
Solution Id:
1058193
Feedback
Did this article help you?

Thank you for your feedback!

To help us improve the quality of this article, please leave your email here so we can clarify further your feedback, if neccessary:
We will not send you spam or share your email address.

*This form is automated system. General questions, technical, sales, and product-related issues submitted through this form will not be answered.

If you need additional help, you may try to contact the support team. Contact Support


To help us improve the quality of this article, please leave your email here so we can clarify further your feedback, if neccessary:
We will not send you spam or share your email address.

*This form is automated system. General questions, technical, sales, and product-related issues submitted through this form will not be answered.


Need More Help?

Create a technical support case if you need further support.