What TCP port to use with SeaCat
Introduction
SeaCat requires to specify one TCP port that is eventually used for client-gateway communication. Clients connect to this port to establish TLS channel that is used to exchange requests and related responses. SPDY-based communication protocol is used for traffic in this channel.

SeaCat: Protocol stack
TCP ports reachability
Google performed investigation during WebSocket implementation (late 2009) that showed surprising facts about success rate of client-to-server connections:
- HTTP port 80: 67%
- Custom TCP port (61985): 86%
- HTTPS port 443: 95%
The reason for low HTTP score is that the Internet is today full of proxies and firewalls that are configured to be transparent to HTTP traffic. However, non-HTTP traffic doesn't successfully pass them. Detailed reasoning can be found here: SPDY Essentials presentation from Google at approx. 18th minute of the video.
443 or custom port
SeaCat communication protocol is up to Session layer compatible with HTTPS protocol stack, HTTPS client that connects to SeaCat gateway is politely rejected with no harm on both sides. SeaCat traffic is indistinguishable from HTTPS traffic for intermediates on the network path, and,therefore, it shares the same success rate of connections. For these reasons TCP port 443 is recommended choice for SeaCat.
If for whatever reason you cannot use this port, use any TCP port above 1024 (non-reserved ports). You will likely got little bit worst connection success rate but still useful for practical deployments in common network scenarios.
Need help?
Do you want to review your SeaCat-related design proposal?
Do you have a question we didn’t cover?
Do you want to give some feedback?
Feel free to contact us support@teskalabs.com.
Most Recent Articles
You Might Be Interested in Reading These Articles
A beginner-friendly intro to the Correlator for effective cybersecurity detection
At TeskaLabs, we know that a cybersecurity system is only as effective as its ability to detect threats. That's why we developed a powerful tool that will prove essential in your arsenal: the Correlator.
Published on March 15, 2024
Log management for absolute beginners
New to log management and cybersecurity? Or, maybe you're already a pro, but you're looking for a way to explain log management to someone who is? Either way, you're in the right place.
Published on April 15, 2024
What Is Mobile Application Containerization or Wrapper, and Why It Needs to Go?
Containerization is an alternative for full machine virtualization. You probably know well-known containerization technology from Docker or Rocket. However, this article addresses the pros and cons of mobile “containerization” or wrapper used to isolate the mobile app from the mobile operating system or other applications installed on the same device. These type of “containerization” work in a different way.
Published on September 27, 2016