Tag Archives: putty

Linux: Convert an openssh key into putty ppk format

Hi,

you want to use a openssh generated ssh key with Putty and PuttyAgent and get an error message like this:

openssh key inport error
openssh key inport error

Continue reading Linux: Convert an openssh key into putty ppk format

Linux: ssh error “too many authentification error”

Hi,

if you cannot logon to a linux machine and you got an error:

ssh - too many authentification failures
ssh – too many authentification failures

Continue reading Linux: ssh error “too many authentification error”

Linux: X11 forwarding not working with putty

Hi,

you have properly configured putty to use X11 forwarding but it fails?

Continue reading Linux: X11 forwarding not working with putty

Linux: Use X11 forwarding with putty and su/sudo

Hi,

when you use X11 forwarding with PuTTY or ssh -X a TCP Socket is opened to which each user can connect. The connection to the X11 itself is protected by an authentification cookie.

Means when you add this cookie to the session launched by su you could use X11 forwarding.

An example. Connect to a linux machine as user michael (by putty or from another linux machine)

michael@debdev ~ # ssh -X michael@debdev1 

In the session of debdev1 list all xauth cookies.

michael@debdev1 ~ # xauth list
debdev1/unix:10  MIT-MAGIC-COOKIE-1  7ea68cc88e74c1697aa6c757504fc0d7 

Note: these cookies are stored the users home directory in file .Xauthority => ~/.Xauthority

Then switch to another user on this machine

michael@debdev1 ~ # sudo su helena

When you try to start a X11 client you got some errors like this

helena@debdev1 ~ # xterm
Can't connect to X11 window server using 'localhost:10.0' as the value of the DISPLAY variable.

Then verify you already have a ~/.Xauthority file

helena@debdev1 ~ # ls -l ~/.Xauthority

If not create a new file

helena@debdev1 ~ # touch ~/.Xauthority

and add the authentification cookie

helena@debdev1 ~ # xauth add debdev1/unix:10  MIT-MAGIC-COOKIE-1  7ea68cc88e74c1697aa6c757504fc0d7

Then you should be able to start X11 programs

Michael

Linux: Creating a ssh keypair with puttygen

Hi,

use the following steps to create a ssh key pair with puttygen and import the public key on a linux hosts.

Start puttygen and generate an 4096 Bit RSA Key.

Generate an 4096Bit RSA Key
Generate an 4096Bit RSA Key

Set a strong password and save it (D:\temp\private.ppk in this example) at a secure location.
Continue reading Linux: Creating a ssh keypair with puttygen