snippetbashTip

ssh-keygen — Generate SSH keys used for authentication, password-less logins, and other things. See also: `ssh-co

Submitted by: @import:tldr-pages·Mar 2, 2026·

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Problem

How to use the ssh-keygen command: Generate SSH keys used for authentication, password-less logins, and other things. See also: ssh-copy-id. More information: <https://man.openbsd.org/ssh-keygen>.

Solution

ssh-keygen — Generate SSH keys used for authentication, password-less logins, and other things. See also: ssh-copy-id. More information: <https://man.openbsd.org/ssh-keygen>.

Generate a key interactively:

ssh-keygen

Generate an ed25519 key with 32 key derivation function rounds and save the key to a specific file:

ssh-keygen -t ed25519 -a 32 -f {{~/.ssh/filename}}

Generate an RSA 4096-bit key with email as a comment:

ssh-keygen -t rsa -b 4096 -C "{{comment|email}}"

Remove the keys of a host from the known_hosts file (useful when a known host has a new key):

ssh-keygen -R {{remote_host}}

Retrieve the fingerprint of a key in MD5 Hex:

ssh-keygen -l -E md5 -f {{~/.ssh/filename}}

Change the password of a key:

ssh-keygen -p -f {{~/.ssh/filename}}

Change the type of the key format (for example from OPENSSH format to PEM), the file will be rewritten in-place:

ssh-keygen -p -m PEM -f {{~/.ssh/OpenSSH_private_key}}

Retrieve public key from private key:

ssh-keygen -y -f {{~/.ssh/OpenSSH_private_key}}

Code Snippets

Generate a key interactively

ssh-keygen

Generate an ed25519 key with 32 key derivation function rounds and save the key to a specific file

ssh-keygen -t ed25519 -a 32 -f {{~/.ssh/filename}}

Generate an RSA 4096-bit key with email as a comment

ssh-keygen -t rsa -b 4096 -C "{{comment|email}}"

Remove the keys of a host from the `known_hosts` file (useful when a known host has a new key)

ssh-keygen -R {{remote_host}}

Retrieve the fingerprint of a key in MD5 Hex

ssh-keygen -l -E md5 -f {{~/.ssh/filename}}

Context

tldr-pages: common/ssh-keygen

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