Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I already created an ssh key for myself sometime in the past. I don't remember "how many bits" it is. How can I tell?

I'm wondering because I'm using hosting at and their faq says:

Can I configure my ssh connection to use a public key?

... we will not install keys that have a length less than 1536 bits ... We prefer that you use a key at least 2048 bits in length, and if you are generating a new key, the recommended length is 4096 bits.

share|improve this question
There's also a similar question on Server Fault. – Cristian Ciupitu Aug 22 '15 at 15:48
up vote 85 down vote accepted
[palvarez@oizon ~]$ ssh-keygen -l -f ~/.ssh/
2048 2e:8c:fd:aa:9f:95:86:9e:b0:d2:a6:1a:7e:d3:3e:74 .ssh/ (RSA)

2048 bits.


  -l          Show the fingerprint of the key file.
  -f filename Filename of the key file.
share|improve this answer
Like your 2nd half, maybe should have read both halfs before opening up the manpage :-) – Puggan Se Oct 11 '13 at 12:00

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.