Work in progress

This page was automatically migrated from the legacy Taggi site ( https://taggi.cse.unsw.edu.au/FAQ/SSH_Key_Files/) and is pending review. Content, links and screenshots may be incomplete or incorrect.

~/.ssh/id\_dsa (protocol 2 DSA),

~/.ssh/id\_ecdsa (protocol 2 ECDSA), or

~/.ssh/id\_rsa (protocol 2 RSA)

and stores the public key in …

~/.ssh/id\_dsa.pub (protocol 2 DSA),

~/.ssh/id\_ecdsa.pub (protocol 2 ECDSA), or

~/.ssh/id\_rsa.pub (protocol 2 RSA)

in the user's home directory. The user should then copy the public key to ~/.ssh/authorized\_keys in his/her home directory on the remote machine. The authorized\_keys file … has one key per line, though the lines can be very long. After this, the user can log in without giving the password.

— From the SSH(1) manual page.

About Passphrases

Creating SSH Keys

If you need a key to access CSE class accounts or other CSE resources, you should log in to a CSE server or lab machine to generate the key

Using SSH Keys

Give a public key to log into an account

Changing or adding a passphrase to a private key

ssh-keygen -p will prompt you for the key to use, the existing passphrase (if it has one) and for the new passphrase.

Common Problems

The public key is in the target account but logins still do not work

If group write permission is enabled on the account directory this can stop users from sshing as the account even though the user's public-key has been appended to the authorized\_keys file of the account. A description of this problem is given in the section about ~/.ssh/authorized\_keys in the sshd manual page. The CSE SSH server is set with StrictModes=yes.

You forgot the passphrase to your private key

There is no way to recover a lost passphrase. If the passphrase is lost or forgotten, a new key pair must be generated and the public key copied to the corresponding target accounts.

Your DSA (ssh-dss) key is not accepted by the ssh client

This issue may occur on computers that are running MacOS Sierra

create an user configuration file in ~/.ssh/config
set permission of this file to 600
add the following lines to enable DSA(ssh-dss) key for the nominated host (which in this example is login.cse.unsw.edu.au) Host login.cse.unsw.edu.au pubkeyacceptedkeytypes +ssh-dss

SSH Key Files