Login with SSH public key doesn't work

Question

So I have my home computer, and my server. I'm trying to login to my server with my private key.

On my server say I have the user serveruser, to which I login from my home computer using

ssh -Y [email protected]

And at my home computer, I have the user homeuser on my home computer.

So now, I want to login to the server using my private key. For that, I already have a key with passphrase in /home/homeuser/.ssh/. So I took the public key (id_rsa.pub), and copied it to my server at /home/serveruser/.ssh/authorized_keys.

Now I would like to login using that key, so I tried to login using

ssh -Y [email protected]

and it still asks me for the password, and not the passphrase.

I tried also logging in using

ssh -i /home/homeuser/.ssh/id_rsa -Y [email protected]

and I'm still being asked for the user password.

What did I do wrong? Please advise.

Thank you for any efforts.

EDIT: According to Mason Heller's recommendation, I executed ssh-add, but it still insists that I input the password for [email protected].

EDIT: Information from ssh -v -Y myserver.com (personal information modified for anonymity).

OpenSSH_5.9p1 Debian-5ubuntu1.1, OpenSSL 1.0.1 14 Mar 2012
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Connecting to myserver.com [100.100.100.100] port 22.
debug1: Connection established.
debug1: identity file /home/homeuser/.ssh/id_rsa type 1
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
debug1: identity file /home/homeuser/.ssh/id_rsa-cert type -1
debug1: identity file /home/homeuser/.ssh/id_dsa type -1
debug1: identity file /home/homeuser/.ssh/id_dsa-cert type -1
debug1: identity file /home/homeuser/.ssh/id_ecdsa type -1
debug1: identity file /home/homeuser/.ssh/id_ecdsa-cert type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.0p1 Debian-4
debug1: match: OpenSSH_6.0p1 Debian-4 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1.1
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ECDSA b2:1a:68:21:5a:72:c4:f7:ec:ea:60:12:e4:f8:b5:71
debug1: Host 'myserver.com' is known and matches the ECDSA host key.
debug1: Found key in /home/homeuser/.ssh/known_hosts:11
debug1: ssh_ecdsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/homeuser/.ssh/id_rsa
debug1: Authentications that can continue: publickey,password
debug1: Offering RSA public key: [email protected]
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /home/homeuser/.ssh/id_dsa
debug1: Trying private key: /home/homeuser/.ssh/id_ecdsa
debug1: Next authentication method: password

More information:

cat /home/homeuser/.ssh/id_rsa.pub

--removed for security--

/home/serveruser/.ssh/authorized_keys

total 4
-rwx------ 1 serveruser serveruser 400 Jan 26 01:09 id_rsa.pub

cat /home/serveruser/.ssh/authorized_keys

cat: /home/serveruser/.ssh/authorized_keys: Is a directory

Solution

/home/serveruser/.ssh/authorized_keys should be a file.

You create it by adding the contents of id_rsa.pub to it (i.e. cat /home/homeuser/.ssh/id_rsa.pub >> authorized_keys).

(Obviously you have to copy the public key to the server first.)

Comments

[Jaap Eldering]

You should run ssh with one or more options -v passed to it, to see whether it loads your private key and tries to offer it for authentication to the server. Pasting it here may offer other people more clues to answer your question.

[The Quantum Physicist]

@JonasWielicki that didn't work... please check the verbose output.

[The Quantum Physicist]

@eldering done, please check the output.

[Marki]

Please show us the following cat /home/homeuser/.ssh/id_rsa.pub, ls -l /home/serveruser/.ssh/authorized_keys, cat /home/serveruser/.ssh/authorized_keys.

[The Quantum Physicist]

@Marki done, please check the output.

[Marki]

See, /home/serveruser/.ssh/authorized_keys should be a file. You create it by merely adding the contents of id_rsa.pub to it (i.e. cat /home/homeuser/.ssh/id_rsa.pub >> authorized_keys). (Obviously you have to copy the public key to the server first.) Now just having you execute those commands should have made you think why cat didn't work ;-)

[Jaap Eldering]

Although ssh-agent makes key management easier, it is by no means necessary to allow public key authentication. Without it, ssh will by default already try to authenticate with a private key ~/.ssh/id_rsa if available and ask for its passphrase if necessary.

[Marki]

You need not use ssh-agent.

[The Quantum Physicist]

Thank you! It works now. But it doesn't ask me for the passphrase... is that normal? I expected that it would ask me for the passphrase every time I log in. And one more question, how can I add more public keys? should I separate them with a new line?

[Marki]

If no passphrase is asked you probably already played with ssh-agent (make sure it doesn't run or logoff/login again). Unless you created a key without a passphrase (it will not say Proc-Type: 4,ENCRYPTED or so when looking at the private key). And yes, you add them by adding new lines to the file. You should probably take a look at man ssh, especially the "AUTHENTICATION" section.