What is the most common symmetric encryption algorithm for encrypting data between two machines with SSH in 2018?

I have attempted to find this out but I generally come across outdated blogs.

I understand that it is most probably currently either AES (in its many forms aes-128, aes-256 etc...) or 3DES.

On one of my Ubuntu servers, I have also checked the ordering via:

man ssh_config

The ordering is AES with 3DES at the end.

Is it safe to assume it is AES or is there a better approach to finding this out?

  • 1
    openssh is using aes256-gcm
    – Aria
    Commented Feb 20, 2018 at 13:34
  • AES 256 is the most common today.
    – Overmind
    Commented Feb 20, 2018 at 13:34
  • Honestly, I think answering this would be a logistics nightmare. Although it may be easy to answer in regards to OpenSSH specifically, you might be surprised at how many legacy or proprietary SSH clients are in use around the world.
    – forest
    Commented Mar 28, 2018 at 2:13

1 Answer 1


It's an unknowable question as asked. There are too many servers in too many data centers to know the most common. You could guess and even take an inventory of every ip on the internet based on defaults and even query the servers themselves. But that excludes internal systems - of which there are many many thousands.

  • 1
    If the question cannot be answered, please comment or flag.
    – Tom K.
    Commented Mar 27, 2018 at 22:08
  • That's fine, but I literally answered the question. Commented Apr 8, 2018 at 23:01

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