Tatu Ylonen, Inventor of SSH

Tatu Ylonen, Inventor of SSH & CEO of SSH Communications Security

Hi, I'm Tatu Ylönen, the inventor of SSH. In English-speaking countries I usually just drop the umlaut from my name, and go with Tatu Ylonen.

I'm an avid technologist and believe in the power of technology to make the world a better place. However, achieving that goal requires that electronic communication must be safe, reliable, and trusted. That was the reason I developed SSH 20 years ago, and that's the reason I'm still at it today.

I designed the original SSH protocol in 1995 and wrote the ssh-1.x and ssh-2.x software. I published it as open source in July 1995. OpenSSH continues the open source tradition based on my original implementation.

Contact Me

Please follow me on Twitter to receive regular updates on top security topics.

You are also welcome to connect via Linkedin if you work with cybersecurity or know me.

I can be reached by email as ylo at, but beware that when I'm busy, it may take several days or even weeks for me to go through all emails and respond. If it is important, don't hesitate to contact again after a few days. Please also respect that I absolutely do not wish to receive marketing emails. I get way too much spam! I generally take a negative attitude towards companies sending me unsolicited marketing emails.

Professional Experience and Interests

Tatu Ylonen is an experienced entrepreneur, a manager, and engineer. He still keeps up to date with technology and loves the technical side and inventing new technology. He participates in product architecture design and occasionally writes code when he has time or when he thinks that's where he can bring the most value.

His primary current interests relate to broader cybersecurity priorities and how to design systems to be more secure. He understands both the big picture and the deep technical issues. He also wants to solve the massive gap in identity and access management in relation to SSH key based credentials.

Tatu Ylonen was the principal author of NIST IR 7966, the best practice guidelines for SSH key management. He has also written the IETF standards on the SSH protocol, including RFC 4251, 4252, 4253, and 4254.

Ylonen is also a frequent speaker at conferences and seminars on cybersecurity, cloud, and digital transformation. He frequently comments on cybersecurity topics in the media. He has received several internationally recognized awards, including the Finnish Presidential Innovation Award and USENIX Software Tools Users Group Award.

Hobbies and Other Interests

In his spare time, Ylonen dances salsa and ballroom, and also has an interest in martial arts. He also enjoys spending time with his family.

He is also interested in (propellantless) space propulsion, natural language understanding, and other technologies that will change the world.

SSH Communications Security

By the end of 1995, Ylonen was getting 150 emails per day asking for technical support. Places like UC Berkeley were asking if he could provide commercial support. Several companies were asking if they could start selling SSH as a product.

Consequently, he founded SSH Communication Security provide support and maintenance services for SSH, to advance its adoption in commercial environments, and to secure the Internet and computer systems.

He grew the company from zero to $20 million in sales and 190 people in five years. The company went public on the Helsinki Stock Exchange (now part of NASDAQ OMX) in 2000.

In the early days, the company did a lot of work on IPSec, a technology for encrypting Internet traffic on the packet level. Its main product in that area was a toolkit for firewall and VPN vendors to implement IPSec in their product. The toolkit was licensed it to over 100 customers, including Sun Microsystems (now Oracle), Intel, Compaq, Nokia, Lucent, and Ericsson.

The company developed some important technologies over the years, including NAT Traveral, which enables smartphones, Voice-over-IP (VoIP), and multiplayer games to work over modern Internet. That was work that Ylonen did jointly with Tero Kivinen. The company still owns the patents on these technologies.

Tatu Ylonen has worked in many roles at the company, including CEO, Chairman, CTO, COO, Chief Innovation Officer, and just an engineer. Today, he's again the CEO and sets the strategy and direction for the company. He runs the company with his COO and management team, and still participates in technical work.

Some of the hot areas the company is working on include:

Earlier Companies

Before SSH, Tatu Ylonen founded New Generation Software (NGS) Oy, which focused on full-text information retrieval - before the Internet search engines. He also founded Applied Computing Research (ACR) Oy, which built databases and transactional file system technology, e.g., for Nokia. He has also been an investor in a few other companies, including Nixu Oy, a security consulting company that went public in 2014.


Tatu Ylonen has a Master of Science degree from Aalto University and also a Licentiate of Technology degree from the same university.