After installing a clean Debian Lenny Xen system using xen-tools, I received this strange error when trying to connect using ssh to the machine:
PTY allocation request failed on channel 0 stdin: is not a tty
It looks like for some reason, xen-tools didn’t install the udev package. So in order to fix this issue, I had to connect (using the virtual console) to the xen machine:
xen console 1
and install udev:
apt-get install udev
strange enough the /dev/pts mount entry was present in /etc/fstab so all I had to do was to remount it with:
(if you don’t have this entry make sure to add it in /etc/fstab:
devpts /dev/pts devpts rw,noexec,nosuid,gid=5,mode=620 0 0
and if the folder /dev/pts doesn’t exist create it first and after that mount -a).
This should fix the ssh problem and you should now be able to ssh into the xen machine. Next to see if this is fixed in xen-tools in Squeeze, and if not to file a bug for it.