In my test environment with Python script I generate on a target server:

SSHException: Error reading SSH protocol banner

simply opening/closing a sufficient number of ssh connection.

Is it classified as a DOS attack against sshd?


Maybe is not classified as DoS attack but I think yes, this could cause DoS if you are able to generate enough traffic. To protect this you can use something like fail2ban


I would say, as long you are not killing SSH daemon it is a stress test. Check the following settings in sshd config: MaxSessions and MaxStartups.

  • Very useful thanks, but you consider that whatever are the values MaxSessions and MaxStartups I can easily saturate them with the Python script. – Bob Oct 16 '17 at 11:27

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