[SOLVED] Problem with passwordless SSH to the same host

adraganov · 06-12-2011, 02:52 PM

Hi guys,

I am trying to run OpenNebula on a set of 2 machines. One of the machines(called host1) must be able to access the others(including itself) with passwordless ssh.
Both machines have the same user and use mounted folder from host1 for home directory(exported with NFS). So single key generation should be enough for this configuration - all the machines have access to the same .ssh folder.
What I am getting at the end is passwordless ssh from host1 to host2 which is great, but no success from host1 to host1. Host2 to host2 is also OK, host2 to host1 wants password like host1 to host1.

Both machines have the same sshd_config and ssh_config files.
File permissions required by ssh should be correct since it works for host1 to host2.
The only difference(I see) between the machines is that host1 runs nfs service, so host2 has access to the exported folders.
The ssh-keygen is executed on host1

authorized_keys has the same public key two times(to authorize access for host1 on host1 and host2).

The distro is Scientific Linux 6.0 aand I also use rsa.
Something else - no pass ssh with another user from host1 to host1 works, so I suppose the problem comes from this mounted folder.
There is something I am missing, so any help will be highly appreciated!

smoker · 06-12-2011, 04:39 PM

Apart from anything else, accessing your private key over a network basically destroys the security of ssh. You should also only need 1 copy of the public key in authorized_keys.

vikas027 · 06-13-2011, 09:34 AM

Try steps given here

adraganov · 06-14-2011, 01:04 PM

Thanks for your responses!

Quote:

Originally Posted by smoker

Apart from anything else, accessing your private key over a network basically destroys the security of ssh. You should also only need 1 copy of the public key in authorized_keys.

Ok, I moved the key pair to a folder that is not exported(outside of the home directory for my user) and changed IdentityFile property in the .ssh/config file to the needed location(call it someOtherLocation/id_rsa.pub). So now I have a pair of keys(id_rsa & id_rsa.pub) in someOtherLocation on host1 and ~/.ssh/authorized_keys file that holds the public key and it is shared between the hosts. And the result is the same - password-less host1 to host2 and password prompt for host1 to host1.
Everything I do is:
ssh-keygen -q -f /someOtherLocation/id_rsa
ssh-copy-id -i /someOtherLocation/id_rsa.pub host1
So for host1 to host1 I expect this to work, but it does not. It works for host1 to host2, since they have authorized_keys file shared in the exported directory.
thats the debug output for ssh on host1

Code:

-bash-4.1$ ssh -v host1
OpenSSH_5.3p1, OpenSSL 1.0.0-fips 29 Mar 2010
debug1: Reading configuration data ~/.ssh/config
debug1: Applying options for *
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to host1 [::1] port 22.
debug1: Connection established.
debug1: identity file /someOtherLocation/.ssh/id_rsa type 1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3
debug1: match: OpenSSH_5.3 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.3
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: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'host1' is known and matches the RSA host key.
debug1: Found key in ~/.ssh/known_hosts:2
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Next authentication method: gssapi-with-mic
debug1: Unspecified GSS failure.  Minor code may provide more information
Credentials cache file '/tmp/krb5cc_503' not found

debug1: Unspecified GSS failure.  Minor code may provide more information
Credentials cache file '/tmp/krb5cc_503' not found

debug1: Unspecified GSS failure.  Minor code may provide more information


debug1: Next authentication method: publickey
debug1: Offering public key: /someOtherLocation/.ssh/id_rsa
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Next authentication method: password

This scenario works for other user that does not use mounted directory as a home folder, but I need it in this way.

adraganov · 06-20-2011, 11:45 AM

My problem was with selinux. I didn't look for what was exactly different between these two hosts in the configuration files and I just disabled it. That's a test environment anyway.
Actually there was a pretty nice message in /var/log/messages about the problem. So everything is fine now!