SSH tries other keys despite specifying a key with -i option

Ahron

8/4/24, 6:12 AM

For the same user, I have two keys on the local machine. On the remote server, both keys are in the authorized_keys file.

I delete one of the keys in the authorized_keys file.

I then try to ssh with the other key using the -i option. It succeeds. The auth log shows that the other (undeleted) key in the authorized_keys file was used to log in - despite me having tried to use the deleted key with the -i option.

Is this normal behavior?

I would expect that ssh only tried to use the key that was specified with the -i option. I know that when no key is specified it tries them all. Shouldn't that not happen when a key is explicitly specified? Or is it more like, tried the specified key first, then try the rest anyway.

Is the expected behavior documented somewhere?

1 + 0

ssh

ssh-keys

Score:0

Server

Ahron

8/4/24, 6:52 AM

Ok, I should have searched more thoroughly. There's an option to do just this.

To make SSH use only the specified identity file, I need to use the -o "IdentitiesOnly=yes" option:

ssh -o "IdentitiesOnly=yes" -i <private key filename> <hostname>

IdentitiesOnly

Specifies that ssh(1) should only use the configured authentication identity and certificate files (either the default files, or those explicitly configured in the ssh_config files or passed on the ssh(1) command-line), even if ssh-agent(1) or a PKCS11Provider or SecurityKeyProvider offers more identities. The argument to this keyword must be yes or no (the default). This op_ tion is intended for situations where ssh-agent offers many different identities.

+ 0

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: SSH tries other keys despite specifying a key with -i option

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.