ssh with DER x509 certificate

umarzuki · 09-13-2009, 11:55 PM

I want to do a ssh login to a linux server with putty using certificate from my usb dongle. I had successfully tried ssh login with certificate if i generated the certificate from that ssh server itself but in this case, it is from ldap server.

Copying that x509 cert (either binary or PEM) into .ssh/authorized_keys asked for password instead of passphrase.

below is sshd_config configurations:

Quote:

Protocol 2
SyslogFacility AUTHPRIV
RSAAuthentication yes
PubkeyAuthentication yes
AuthorizedKeysFile /home/user1/.ssh/authorized_keys
PasswordAuthentication no
ChallengeResponseAuthentication no
GSSAPIAuthentication yes
GSSAPICleanupCredentials yes
UsePAM yes
AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
AcceptEnv LC_IDENTIFICATION LC_ALL
X11Forwarding yes
Subsystem sftp /usr/libexec/openssh/sftp-server

is it in the configuration files or in the certificate?

Matir · 09-14-2009, 07:26 PM

Are you using a version of OpenSSH that supports x509 certificates? The only one I know of is http://roumenpetrov.info/openssh/, which isn't installed by default on any distributions.

umarzuki · 09-14-2009, 07:43 PM

I don't believe I'm using one. Is there any known putty (ssh client) that supports x.509 and do I need to compile sshd on the server to a version that supports it?

jschiwal · 09-14-2009, 08:15 PM

Can putty's puttygen.exe program load the certificate you have. If so it should display the openssh compatible version of the public key in the top which you can copy and add that to the end of the authorized_keys file on the ssh server.

If not, look at "openssl x509 --help" for conversion options.