Open any of the above terminal emulators and write ssh root@192.168.1.1 (“ssh” is the command, “root” is the OpenWrt user you are connecting to, and “192.168.1.1” is OpenWrt default IP) there will be a message about accepting a new key from the OpenWrt device, write “yes” and press Enter key. Open any of the above terminal emulators and write ssh root@192.168.1.1 (“ssh” is the command, “root” is the OpenWrt user you are connecting to, and “192.168.1.1” is OpenWrt default IP) there will be a message about accepting a new key from the OpenWrt device, write “yes” and press Enter key.
Teleport is an identity-aware, multi-protocol access proxy which understands SSH, HTTPS, Kubernetes API, MySQL and PostgreSQL wire protocols. On the server side, Teleport is a single binary which enables convenient secure access to behind-NAT resources such as: SSH nodes - SSH works in browsers too! Kubernetes clusters; PostgreSQL and MySQL.
-->You cannot connect to an Azure Linux virtual machine (VM) by using Secure Shell (SSH). Approaching blocks crack. When you run the Boot Diagnostics feature on Azure portal, you see log entries that resemble the following examples.
Examples
The following are examples of possible errors.
Example 1
Example 2
Example 3
Example 4
This example is caused by a clean fsck. In this case, there are also additional data disks attached to the VM (/dev/sdc1 and /dev/sde1).
This problem may occur if the file system was not shut down cleanly or storage related issues. The issues include hardware or software errors, issues with drivers or programs, write errors, etc. It is always important to have a backup of critical data. The tools that describe in this article may help recover file systems, but it is data loss can still occur.
Linux has several file system checkers available. The most common for the distributions in Azure are: FSCK, E2FSCK, and Xfs_repair.
Resolution
To resolve this problem, boot the VM into emergency mode by using the serial console and use that tool to repair the file system. If the serial console is not enabled on your VM or doesn't work, see the Repair the VM offline section of this article.
Use the serial console
Ssh V1
Connect to the serial console.
Note
For more information about using serial console for Linux, see:
Select the Power icon button, and then select Restart VM. (If the serial console is not enabled or not connected successfully, you won't see the button.)
Boot the VM in to emergency mode.
Enter the password of your root account to sign in to emergency mode.
Use xfs_repair with the -n option to detect the errors in the file system. In the following sample, we assume that the system partition is /dev/sda1. Replace it with the appropriate value for your VM:
Run the following command to repair the file system:
If you receive the error message 'ERROR: The filesystem has valuable metadata changes in a log which needs to be replayed', create a temporary directory and mount the filesystem:
If the disk fails to mount, run the xfs_repair command with the -L option (force log zeroing):
Next, try to mount the file system. If the disk is mounted successfully, you will receive the following output:
Restart the VM, and then check if the problem is resolved.
Repair the VM offline
Attach the system disk of the VM as a data disk to a recovery VM (any working Linux VM). To do this, you can use CLI commands or you can automate setting up the recovery VM using the VM repair commands.
Locate the drive label of the system disk that you attached. In this case, we assume that the label of the system disk that you attached is /dev/sdc1. Replace it with the appropriate value for your VM.
Use xfs_repair with the -n option to detect the errors in the file system.
Run the following command to repair the file system:
If you receive the error message 'ERROR: The filesystem has valuable metadata changes in a log which needs to be replayed', create a temporary directory and mount the filesystem:
If the disk fails to mount, run the xfs_repair command with the -L option (force log zeroing):
Next, try to mount the file system. If the disk is mounted successfully, you will receive the following output:
Unmount and detach the original virtual hard disk, and then create a VM from the original system disk. To do this, you can use CLI commands or the VM repair commands if you used them to create the recovery VM.
Check if the problem is resolved.
Next steps
Ssh Version
One of the advantages of writingbooks is that you must double-check everything you thought you knew about a topic. PuTTY is probably the most widely deployed SSH client in the world. Total war: napoleon - definitive edition download for mac. I’ve used it for years. It’s good software. (I also use the OpenSSH client, of course.)
To my surprise, PuTTY accepts both version 1 and 2 of the SSH protocol. It prefers version 2, but will accept 1.
Version 1 of the SSH protocol has irremediable problems. If a client accepts SSHv1, an attacker can intercept a new SSH connection and force it to downgrade to SSHv1. He can inject arbitrary commands into the SSHv1 stream. These problems have been known since 1998. Increases in computing power have made executing these attacks much simpler.
Worst of all, Ettercap can decode SSHv1 in real time. If Wireshark cannot decode SSH now, I suspect it will soon.
In my mind, this puts SSHv1 into the same category as Telnet and unencrypted read-write SNMP; stuff that Just Should Not Be On My Network.
I absolutely understand why PuTTY supports SSHv1 by default. The generous people who spend their free time writing PuTTY aren’t interested in supporting folks who can’t be bothered to read the instructions. I might make the same decision in their place.
And yes, host key verification helps eliminate MITM attacks. But do your users really verify host keys? Really and truly? The PuTTY FAQ lists “How do I turn off the annoying host key verification prompt?” as a question. As a sysadmin, I translate this as “yours users don’t verify host keys, and mine don’t either.”
There’s no reason for anyone who actually reads this blog to routinely permit SSHv1, and the appearance of security is worse than no security. I encourage you to disable SSHv1 by default in your and your users’ clients. Users can override the default on a host-by-host basis, but at least they must make the conscious effort. They’ll probably ask you for help. This will help you find lingering SSHv1 servers. If you have some embedded device that only speaks SSHv1, well, you have a job to do. That job should include replacing that device or yelling at the vendor.
How do you disable SSHv1 in PuTTY? Open PuTTY. On the left side, go to Connection->SSH. Select “2 only.” On the left side, select Session (at the top). Highlight “Default Settings.” Click Save. PuTTY saves its configuration in the registry, so you can export this setting and apply it to your client PCs through whatever method you use.
The most annoying part of this change is that PuTTY’s default settings do not propagate to all of the previously saved sessions. You must update them by hand or recreate them. I suspect that you could use some sort of script to update your saved sessions from your registry, but I can’t find such a thing. (This would be a great add-on tool for some Windows programmer looking for a way to contribute to the community.)
I will continue to highly recommend PuTTY to my Windows-based friends, with a note on how to disable SSHv1. As a lowly user who has no right to complain and who doesn’t have to listen to users whinge, though, I’d like to say to the PuTTY folks: researchers broke SSHv1 thirteen years ago. It’s time to stop accepting it by default.
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